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[Music] thank you Network fundamentals basic Network Theory and terminology Network fundamentals is our first lesson since before we can get into discussing networking and its complexity we need first need to Define some of the terms some of the theory and get a nice framework for where we're going to be going one note about the network plus exam is that they assume you have around 18 months experience in the industry if you don't that's okay but I am assuming that you do have some basic knowledge of computers and perhaps some working knowledge of networks so in some cases this might be redundant for you and in other cases you might be learning some new stuff either way I'm going to focus on exactly what the network plus exam wants to see and what you need to know to pass so in this module we're going to be introduced to networks and what makes up a network the terminology that's used to describe those objects it becomes flexible after a little bit of time and experience spent on the field but to understand what each object does and what its functions are in a network I want to break down some of the jargon or the technical speak and talk about what exactly is networking so some of the module objectives that we're going to cover are first to Define and describe a network and a computer network you've heard the term Network before and so I want to Define what that is and how that relates to a computer network next I want to describe the components of a network what makes a computer network I want to define the terms node and server which will be helpful going forward when we use those terms Define and describe the network backbone and the various variations of a network backbone and finally I want to define the difference between a terminal a client and a peer all right so let's get started now because networking is ubiquitous we need to define a few specific things in order to keep things in order so first Network this is an interconnected or interrelated chain group or system generally based on a purpose so for instance if we say that you're going to Facebook or LinkedIn are social networks because the purpose is to be social and to connect with other people who have similar interests likes Etc in the same way you are interrelated and you form a group now based on that a computer network is the interconnecting of two or more computers that have a basic core purpose of communicating electronically so the network of social network is to communicate with individuals about a specific topic on a computer network we need to communicate data electronically and that's the thing that joins us together the internet is one really large computer network and we will see how that comes to play later on in this course now whether your network is comprised of two computers or two thousand computers or like the internet two million computers there are uh some commonalities in networks and requirements for what makes them the first thing that are needed obviously are devices these are the actual computers the printers the switches the routers all of the devices that are going to be connected together by media now media can either be a physical connection such as copper or newer forms such as fiber optics or it can be something Wireless like Wi-Fi or a radio frequency or even cellular Wi-Fi each device however has its own language when networking and not every device knows how to communicate with the language of these other devices right because obviously a computer communicates slightly differently than a printer slightly differently than a router Etc so in order to allow all these devices to communicate with the rest of the network we have something called a network adapter sometimes referred to as a network interface controller or a NIC specifically in the term of computers and it serves this network adapter as a translator between the components the devices over the media by which the data is sent so finally to manage and govern how everything talks with everything else the network needs an operating system which is similar to like the ring leader in a circus if we can use a a metaphor there it tells the network how to work together in order to perform as efficiently as possible over the adapter over the media and with each of the devices without the operating system there wouldn't be any order or Direction in the network and no one would really know what they were doing so the network operating system is responsible really for allocating resources monitoring the activities of devices on the network over the media and managing files and data Etc now we have two devices that I want to Define one is a node and a node is any device that is connected to a Communications Network and this can be just about anything so we have uh clients and servers our nodes and so are printers and network attached storage devices and these are all what we call endpoint nodes I'm going to write that up here because that's where the data ends whereas something like a router or switch or previously we used to see a lot of hubs do what's called redistribute so those are what we call redistribution nodes okay so it's important to understand that these are both nodes anything on the network really any sort of device that's communicating is a node or being communicated with the endpoint nodes where or where the information sort of ends up or is going to a redistribution node its responsibilities to pass the data on to another either redistribution node or onto the endpoint node now a server is a network device that's responsible for sharing resources and managing certain services like addressing and we'll talk about this which is called an IP address a little later it's also uh manages devices on the network and controls the network-wide functions like permissions so not only is it going to give uh all our clients all the other nodes addresses that allow it to communicate it's also going to manage how those devices communicate and what they're allowed to do which is what we call permissions all right now this is um so you can see that the server is a type of node but I just want to describe server we're going to talk about some of the other um devices in just a moment before we do that let's talk about the network backbone okay the network backbone is responsible for carrying the majority of network traffic and it works very quickly at a very very very high speed now it might use different technology throughout this um on the backbone that's different from the rest of the network because it basically connects all the smaller networks together that's why it's called the backbone and it needs to be large fast and um capable of communicating at very high speeds because all of these computers all these smaller networks are communicating we'll talk about how that all works in a bit now there are four different types of network backbones and we're gonna I'm just gonna give you a brief definition of these now and we will come back and talk about these more in depth a little later okay the first one is called serial that's where one backbone cable connects to another one after the other like so all right so there's one backbone cable and multiple switches are connected to that cable which allow devices to connect to it there's also something called a hierarchical or distributed uh um backbone which like a family tree it has more of a family tree layout if you can imagine right okay and this backbone is in this case it's much easier to manage typical for what we'll call local area networks or lands it's much more easily scalable as you can see because I can update one part a lot faster and in this case the backbone is responsible for the traffic of the nodes on each branch so we have different branches and on each branch the backbone is responsible for that and that's how it gets a little easier now A collapsed uh backbone uses a router as the Connecting Point all right and we'll talk more about how that works a little bit later and what exactly a router does and how that's different from a switch and that's a pretty major point finally we see something called parallel which is just like a collapsed uh backbone except it has multiple cable connections and that's because that allows for more redundancy remember if you took the A Plus Class we talked about redundancy and how we want to make sure uh that we don't have what are called single points of failures so there's more than one cable connection which not only is great for redundancy it also allows for what's what we call load balancing and also a faster throughput because the computer can decide which of the cable connections to use all right so these are again we have serial hierarchical or distributed collapsed in parallel as we talk more about networks these differences will become clearer but I just wanted to cover them now and you won't probably see these specifically on the exam in this format you'll see them in other formats and but I want to lay the framework for what we're going to be talking about all right now a terminal terminal is a network Hardware device that's used for entering date data into it and displaying data from another computer Computing system it's commonly called a dummy computer because it doesn't have any processing capabilities of its own it also doesn't have much memory or anything else okay so it is literally this is a dummy it's basically a screen with a keyboard a mouse some sort of input tool right and what it's doing is simply displaying information on a bigger better server computer someplace else all right we also need something called a terminal emulator placed onto this computer so that it can emulate what's going on on the server and communicate with it since it doesn't have processing capabilities or memory of its own now this is different from what's called a client a client has its own processor and memory of its own but it accesses network resources on other nodes other servers and other clients all right so it is um rather than a server which serves up information the client takes the information and uses it now appear is a network computer that provides its own resources and services and computes on its own the best thing about appear is that it can act it is self-managed self-contained and it is both a server and a client okay so you can see how this works this cloth this peer computer serves information to this peer computer as a client this computer can serve information to this one as a client so this is what we call peer-to-peer networking it manages its own set of local policies it has its own set of users it is completely self-contained and does not need a server to operate unlike a client which does all right so just to recap what we've talked about we were we we defined what a network is and how that's different slightly from a computer network which is really what the network plus exam covers we describe the components of the network uh the adapter the network operating system the devices the media let's go ahead and write those we had media right which allowed the devices to communicate using a network adapter communicated and managed by an operating system we also defined a node and server right the node is really any um sort of device that's on we have the end point and we also have a redistribution we Define and describe the network backbone remember which is really fast and the different variations of it which if you recall included cereal which is one after the other hierarchical also called distributed then we looked at collapsed and a more redundant form parallel finally we defined terminal client and appear remember the terminal is a dummy client accesses resources on other computers and appear both serves and accesses all right so now that we've covered some of this basic terminology let's continue on talking about the fundamentals of a network And discussing more of what we need to know in order to get into the majority of this uh information on the network plus exam [Music] thank you Network fundamentals Network categories and models having discussed some of the basic components of a network and having established sort of a baseline of some terminology that we all need to be familiar with I now want to talk about the different categories of networks and as we begin to understand the differences between these categories we're also going to look at some of the basic models that networks are placed into depending on different configurations and layouts so our objectives in this module are first to describe the characteristics of a lan or what's called a local area network now this is different from a Wan or a wide area network you're going to need to be familiar with both of these terms and actually we're going to see a few different types of lands including uh man's pans cans and uh none of these are what you think these are all acronyms so a man is a metropolitan or a municipal area network uh pan is a personal area network can campus area network etc etc and as you can see from the name these these terms are really um amorphous so it really depends on some subjective uh opinions as to what these types of networks really described but anyway we're going to cover all of those so you'll be prepared for them if if and when you see them out in the field or on the test we're also going to define the difference between the internet something that I'm sure you all have heard of and then two other terms the intranet and the extranat which are more uh specific towards organizations and sort of uh uh using internet Technologies uh for a specific organization we're then going to look at uh the way networks basically are organized we're going to look at something called a centralized Network which if you recall from the previous uh video is going to involve a terminal and a Mainframe and then we're going to look at a client server Network which sort of takes the pressure off of that Central Mainframe and puts it onto a server with a client and then finally we're going to look at what a peer-to-peer network is and again that is like where we have all clients no servers so we're really looking at a descending order of centralization but at the same time we're putting more power and resources into the individual computer finally because nothing is as simple as it seems we're going to look at what's called a mixed mode Network which is a combination of sort of all of these and that'll help us as we go forward understand how an administrator of a network something we'll also talk about uh deals with these different types of needs on their entire network so let's first start talking about a local area network a lan or a local area network is a network that spans a small area typically either a building like your home or office or a floor of a much larger building you might find this in like a skyscraper so take the Empire State Building for instance which is one of the largest or tallest buildings in New York or it used to be um every floor of the building might have a different company using it so each one of those has their own land or local area network to keep them separated from one another even though they might even be using some of the same infrastructure running into that building now in a land the most commonly implemented technology and something you've probably heard of is something called ethernet and this means that the communication path taken utilizes uh cabling or short range Wireless Technologies we're going to talk about ethernet and and really what it means because it's it's also not just the hardware it really has to do with how the data is being communicated in Greater detail in an upcoming module now in a local area network a connection uh is leased by a service provider but it isn't necessarily for the land to function properly so this means I don't need an outside sort of connection in order for my land to work the reason I might need a connection to the outside from an internet service provider is going to be thanks to a Wan or a wide area network but let's talk really quickly about land administrators the people who are running these lands that might help us understand them a little clearer now land administrators are like jugglers they have to keep their eyes on all of the components of their Network at the same time hence the little GIF over here they have to have there for a broad range of versatile skills that allow them to manage and maintain all the different parts of their Network now that's only within their domain and the juggler also has to be mindful of each of the objects in the air at the same time or else they might lose track of one or all of them like the juggler if the land administrator loses track of one part of their job it's likely the entire network of moving components could come quote unquote crashing to a halt the land administrator therefore has to have a strong working knowledge of all the aspects of their Network now the land administrator should be able to handle tasks such as installation of software and hardware troubleshooting all components of the network including the servers which we'll talk about connectivity devices and media and so on and so forth and not to mention security for the network so if that isn't enough one of their most difficult tasking duties of the land administrator is being responsible for users and attending to their requests and their requirements so you can tell that the land administrator really has to be able to do a lot and we're gonna as we go through this course you'll see more and more specifically of what they have to do but let's talk about a Wan a Wan or a wide area network uh is a network that spans a larger geographical area than a lan in most cases uh the WAN is going to connect as this picture demonstrates multiple lands together and it might even utilize long-range communication such as satellite or radio frequency otherwise known as RF now one main factor that differentiates a win or wide area network from a lan is that it can enable users to connect to one another from different physical locations so whereas these are each physically sort of uh isolated in some ways you can tell the WAN connects all of these lands together okay now a Wan can be private where an organization has complete control of access to it resources and it's solely responsible for everything that occurs on that Network or a win can be public and of course the world's largest Wan is the internet now we're going to talk more about the internet in detail shortly but I just want to point out that the biggest wide area network we have is the WAN and unlike the land which is geographically isolated and can be controlled by a relatively few number of people the WAN has very different needs now there are also different types of lands that are out there now some of these classifications um we might get argument from certain individuals just because this is sort of open to some subjectivity but these are covered on the examine which is the reason I want to make sure we cover them the first one that we've seen a few times when we talked if you were here for a plus is called a pan or a personal area network a pan is two to three computers connected together by cables and a wireless pan or wpn is going to be using Bluetooth or infrared Technologies generally speaking when we are talking about pans uh for purposes of the exam we're really talking about Bluetooth now I might consider pan a sort of local area network but for our sake we're just gonna group this into wands right now but this could be considered something a little different okay so I'm just gonna sort of put brackets around that and a w pan or a wireless pan if we put that W in front of it uh occurs when the computers are connected together wirelessly but not through an access point right so they're connected literally uh to one another thanks to the wireless technology but there is no sort of Central Access Point that they all connect to now the next type is a can or a campus area network and I'm assuming from the name you can guess that this is a Wan that spans the geographical area comparable to like a school or a campus or a business park such as Yahoo now again some people might consider this a land some might consider this a win but for our sake we're just going to assume that this is dealing with some sort of Campus some sort of school some sort of area that is contained all by one organization so for instance if I had uh four buildings all connected uh and each of them has let's say four floors right there might be a lan on each floor or in each building and then connecting each land together is going to be this can which is a sort of wide area network but because the wide area network could denote uh the internet and the cloud is sort of the best descriptor of that we want to call it something slightly different now a man is a metropolitan or it could also be a municipal area network and as the name implies It's relatively the size of a city or a town or a metropolitan area so if I have a business that like the cam uh has several buildings but the buildings are now separated over the course of the city as opposed to some in my own campus then I'm probably going to use this terminology again or a global area network I think it's sort of redundant but these are networks that go from country to country or around uh these are networks that go all the way from country to country all the way around the world they span the globe and they're going to utilize Technologies uh like satellite probably and the reason we're going to call this uh again is because generally speaking the global area network again is all controlled by one sort of company as opposed to a Wan which as we just discussed could include either all being controlled by one company or all being controlled by uh you know disparate companies such as the internet finally an En which is the only one that breaks from this convention is called an Enterprise Network it's a network that includes usually aspects of both a Wan and a lan and it's typically owned and operated by a single entity or organization just like a gan might be now again these terms are very fluid and flexible and depending on who you talk to they'll call it different things so you might I worked for a an organization we never used the word man we always use the word when talking about the network that was deployed over the entire city however certain individuals certain organizations will call these different things and the names might change as well but it's important to have a firm understanding of this just from a basic you know definition standpoint but also so that if you go out in the fields and you hear people talking these different terms you can talk the talk as well now unlike land administrators whose Duties are quite varied when administrators are typically specialists in their respective Fields so they're responsible for more complex infrastructures and as a result uh they need to be more fluent in say routing structures and troubleshooting different difficult or different network issues they're also responsible for say data versus voice systems and when administrators concentrate generally on network oriented problems and not user related issues like a land administrator so with a a lan we're really going to get these user-oriented tasks right because they're dealing with the user on a day-to-day basic a Wan administrator is really not dealing with these or they're dealing with sometimes what we would refer to as the back end and in some cases as well they're also going to be a little more specialized in what they do since what they're dealing with is a lot more complex a lan administrator can sort of be a jack of all trades a wand administrator we want to be a master of exactly what it is he or she is dealing with uh one of the other main duties of a Wan administrator is the development and implementation of certain scripts that are going to automate certain Network processes and they're also going to plan for and test and push out upgrades and updates to the infrastructure of the network network wide whereas a land administrator is going to do this on a sort of local basis perhaps to the computers in their Network so we can see sort of how these are getting differentiated here a Wan administrators a lot more specialized and they're not focused on user oriented tasks they're looking at Network stuff so you can see a Wan administrator again dealing with the back end much more specifically generally more Technical and generally also a little bit more training than a land administrator now let's talk about the internet or the World Wide Web which is a public wide area network right it is the largest Wan that we have and it essentially connects every country on the planet in some ways every computer on the planet it's used for many different things including but certainly not limited to sending and receiving email initiating and completing commercial and private transactions uh commute communicating and allowing people to connect to one another that are sitting in the same room or perhaps even on the other side of the world the internet is really the method by which everyone in the world can communicate in one way or the other and in some ways we can actually use it to create our own virtual lands that are private and we'll talk more about that the other thing that's important to know is every bit of data is stored somewhere on a server typically in the form of a web page and in order to access the data data on the internet you're going to have several different considerations that are going to be made first of all you need to have a web browser of some sort or you're gonna need to utilize a certain generic protocol and have something like uh so if we're talking a web browser we're gonna need to use a safari Internet Explorer Google Chrome Firefox Etc but they're all using HTTP which is a specific protocol and it has a certain port which by the way is 80. we'll talk more about those later in order to allow communication to occur and this might be different from say another form of communication such as FTP or remoting in and so on and secondly all devices that want to connect to the internet must be assigned we would call an IP address all things on the internet due to the way it works are governed by this IP or the Internet Protocol we're going to revisit this in a future module but IP allows all of this to happen if it wasn't 4ip we wouldn't have an internet at least in the way we know it so again the internet is this largest global wide area network that we have in the world and it's for use it's public and everyone can use it if they you know have a provider that gives them access now this is different from an intranet an intranet is a company's private version of the Internet it's commonly connected to the internet so that people can uh connect even if they're not locally at the same place physically but the purpose of an intranet is to keep your network or portions of your network segregated from the unsecure and possibly even dangerous internet so a company might use an intranet for security purposes or for confidentiality if they have certain files and folders they want to post up and the intranet uses the same services and protocols as the internet so the reason it shares this name is intra enter to the organization but it shares the same name because it's using all of the same services in other words IP HTTP you still use a browser so on and so forth so it's still accessed the same way you would the internet through a browser and a web page on the world wide web now all of this is different from an Extranet as the name implies with an intranet your network is completely secure from the internet right you control who has access to your network in every facet but what if your company organization needs to allow certain individuals to have access to your network but you don't want them to have access to all of your network in this case we're going to use something called an Extranet it gives you the ability to Grant uh access to specific portions of your network and your Extranet so you can give access to specific people typically vendors suppliers individuals that might need minimal or temporary access at the same time your Extranet is restricting them from having full access to the rest of your network or your intranet so it's really an extension of your intranet but it's the part that is exterior look at that extra to your organization so again the internet is is a you know using a certain degree of protocols and uh technologies that allows anyone in the world to access information the intranet is sort of a private internet for your organization and the Extranet is the part of that intranet that you're going to let other people from outside of your organization have access to now I just want to Define what a segment is since we might see this term come up a bit in the future a segment is a portion of a Network that has linked devices and that are separated by a connectivity device such as a switch or a router all right so we haven't talked about switches and routers yet but we're going to and so what I mean is I might have a lan okay and let's say that for simplicity's sake My Lan is consisting of four computers all connected through a central device which we're going to call a switch now remember if they weren't connecting through that Central device this would be called a pan a personal area network but this is a lan has a central device and let's say this Central device and this I'm really simplifying it but let's say it connects to another switch and that other switch has four computers connected to it now I have different segments of my network that uh I can join together in certain information but I can also exclude them from certain information in order to allow for performance by segmenting we allow communication between the nodes on each segment to be uninhibited by the traffic on other segments so I'm not worried about uh if if computer a wants to talk to computer C I don't need to involve all of these guys I can just allow them to talk directly and so what it's doing is it's it's basically keeping a lot of traffic from going over this line and therefore we're increasing speed we're increasing throughput and we're decreasing the amount of sort of errors that can occur and we're segmenting everything out to make it easier to fix in the future as well now let's talk about a network model we've just talked about some Network categories so now let's talk about the different models that these are going to fit into a network model is a design uh specification if you will that identifies the transmission path that nodes on the network are going to use in order to communicate it basically determines whether the communication and the processing is centralized or distributed so in a centralized Network this is where we have our Mainframe in our terminals the host computer this guy the Mainframe provides all of the processing and all of the network communication and the users that interface with the host computer do so through these Terminals and by using a terminal emulator that's on the screen centralized networks are highly effective but the problem is they can be a little costly to maintain because this sucker right here needs to be so powerful that what if I have instead of just three computers what if I had a thousand computers and what if this goes out well now I'm in major issue I have a major problem so this is why a lot of times we use what's called a client server model the client server model it in the client server model the server is responsible the server right here is responsible for providing services like file sharing and printer sharing and authentication services and data storage and management to these clients the main difference between the centralized and the client server model is that in this client server Network the processing and the resources can be allocated wherever they are needed including on the client and they can also be distributed whenever necessary and the end nodes These Guys these clients can still perform their own processing and end user tasks without having to constantly talk over to the server so if I need a file for instance I can get that file do the work on my computer and then I can save it back to the server whereas here on the centralized Mainframe terminal setup all the work is actually done on this major huge computer and here in the terminal we're just sort of having a portal to see what's going on now both of these are different from what we call a peer-to-peer Network we talked about appear in the previous module but a peer-to-peer Network which you might also see as P2P or PTP uh is a network in which each node on the network is responsible for its own Computing its own management its own security its own storage its own resource sharing like printers it's completely decentralized and it's commonly referred to as a work group now this is sort of like if we were going to make a reference to a political metaphor this would be like communism everyone works together equally and everyone is responsible for their own thing and then they can share that with everyone else whereas in a client server sort of uh model we're dealing with say a democracy in which you have a president or prime minister someone who's going to make a lot of the decisions but you are still at Liberty to exercise a lot of your own stuff and that's very different from say a terminal Mainframe which is would be equivalent to like a monarchy a really strict here I should say tyrannical monarchy in which everything is decided for you and you make no decisions on your own so one of the problem with work groups is that user accounts need to be replicated onto each node so that if I want to get access to this computer and I usually work on computer y all of my username password everything is going to be on there and if it's not done if I don't sort of copy everything over there's no way I can gain access so this is the problem with this model is each person's their own but if x has wheat and I have corn there's sort of no sharing that's automatically set up we have to create our own sort of share and then if someone else says something I have to share with them and so on and so forth now we might sometimes mix these together into what's called a mixed mode Network and that's just like it sounds it mixes aspects of two or more of the different network models an example might be a work group of computers connected together via some sort of short range Wireless while allowing those computers to connect to a Mainframe computer and using terminal emulation so alternative we might have a work group and then a centralized server Etc so we see we can see mixed mode networks they're usually uh not as popular in huge Enterprises because of the lack of control um except in certain specific instances uh but we do see them and it's important to know that just like in anything we can mix and match to however we want the the network to work all right so now just to recap what we've talked about we can now describe and Define the characteristics of a lan or a local area network as well as a Wan or a wide area network and we also talked about several of the uh different types of lands or in some cases lands including a can or campus area network a man or municipal or metropolitan area network a pan or personal area network which is where the computers connect directly to one another and then we looked at a gan or a global area network and then we also talked about en or an Enterprise Network okay so these are all uh different acronyms that you need to learn for the exam we also talked about uh an internet intranet an Extranet remember the internet is that World Wide Web right the cloud the intranet is sort of using this Cloud but in your company and keeping it private that's my little building and the Extranet is allowing access of your company private intranet to perhaps certain individuals from outside so it's just a little bit of that we also talked about a centralized Network which is mostly what we talk about when we deal with terminals and mainframes and we'll sort of deal with this a little bit too when we get into uh virtualization when we talked about Thin and Thick clients this is the idea of a thin client on a network with a a server of some sort or a Mainframe I should say that is going to do all the processing for it we also looked at a client server Network which is the majority of the types of networks we see in Enterprise settings and a peer-to-peer Network which we also call a work group network in which every peer is both a client and a server responsible for its own um its own resources and so on I think we use the metaphor that this might be like uh communism this might be like a client server might be like sort of uh democracy of some sort or a republic of some sort and a centralized Network would be more like I guess I should say a democracy that is also republic since um we do have officials and there's someone above us right but a prime minister a president sort of system and then a centralized Network would be like a tyranny or a tyrannical Monarch I should say and then we have a mixed mode Network which is sort of a combination of uh the above great so we've talked now about uh some of the basic terminology we've talked about the models we've also talked about the different categories so let's finish up this basic Network fundamentals area by talking about what are what are called topologies how the networks are physically set up and how they logically communicate with one another [Music] thank you Network fundamentals Network topologies so now we're going to explain Network topologies or uh the network layout both physical and logical physical being how it's physically connected and logical being how the information is communicated over that physical Network and we're going to define the different standard topologies that are in use for today so uh we're first going to Define topology in general then we're going to talk about physical topology followed by logical topology we're then going to explain a few of the different types of topologies you need to be familiar with for the exam including a bus topology star topology a ring topology a tree topology and a mesh topology we're also going to talk about a mixture of all of these topologies that is called a hybrid topology these are the things you really want to pay attention to these different names and the names correspond directly to how everything is set up so I don't think it'll be too hard for you to remember or to memorize so as administrators regardless of the specific role we're in we have to have a complete understanding of the layout or the arrangement of the network this allows us to effectively design manage and troubleshoot the networks for performance and scalability a scalability by the way I'm just going to write that out here because it is a term we'll see come up over and over again is um how you can either make the network larger or smaller depending on needs certain topologies have characteristics that allow us to have more efficient communication while other topologies focus more on immediate or faster communication between certain devices so understanding the topology of the network allows us administrators to troubleshoot the problems we're having and then Implement Solutions easier and more efficiently so there are two types of topologies in general and then there are specific names for each of those topologies but the two types are physical and logical so uh let's take a look at the characteristics that define a physical topology and a logical topology Google topology is the actual physical layout of the devices so this is like looking at the blueprint of our Network this tells us how the devices are actually physically connected to one another it's also the shape of the network and it gives us a sort of picture to represent the layout or the blueprint the physical topology ensures that we administrators know and understand how the physical media like cables connect the devices to one another so a logical topology on the other hand describes the how in other words it's the pathway that data takes regardless of how the network is physically laid out this is how the data is actually communicated over the physical so the logical topology allows administrators to troubleshoot and fix the problems we're having with communication between devices by understanding the path that the data is actually taking and we'll see some pictures of this in just a second so that will make this all a lot more clear in a lot of cases the logical topology could be very different from the physical topology so only because one logical topology is for instance the star doesn't mean the physical topology is also going to be a star you can have a physical star and a logical bus so that's why it's important we understand but the difference between logical and physical so now that we've defined the difference in a physical and a logical topology I want to look at some of the different connection methods that we use in these topologies in the specific layouts both for physical and logical uh but first let's talk about how these things connect because that's going to keep coming back up so the first type we have is called a point-to-point connection this is a direct connection between two nodes on the network and remember when we're talking nodes that could be two computers uh printers Etc and remember we had endpoint nodes and then we had redistribution nodes so this these can either by the way be wired or Wireless so an example of a wireless point-to-point connection would be for instance two nodes using an infrared connection to communicate with one another like your TV and your remote control a wired point-to-point connection on the other hand would be two computers with network interface cards or nics remember that term okay connected directly together with what's called a crossover cable so there's nothing in between them right they're connected directly to one another using cables this might also be the same thing we do if we connected two computers together somehow using USB uh cables although that's not really going to happen very often in a network setting the next type we have is called a multi-point connection now as the name implies we had point to point that's like one to one and then we have multi-point connections which means that there are connections between multiple nodes so there are two or more endpoints connected together by each multi-point Connection in other words all transmissions are not private because every node on the network can detect the signal being transmitted now there's also something called a radiated connection and as the name implies radiated this is specifically a wireless connection so data is transmitted wirelessly between devices it's also by the way called a broadcast connection uh although broadcast also means something different as we will see in just a minute so some radiated connections would be like Wi-Fi or wireless LAN and in some cases even an infrared like your um a remote control but the reason that that's a point to point is it uh infrared requires direct line of sight whereas radiated connections that can be either point to point or multi-point so it sort of is uh it sort of involves all of these different ones all right now let's talk some about some of the specific uh topologies the first one I want to talk about is a physical bus topology not a logical bust apology okay so again this is the physical how things are physically connected and what this means is each node is arranged as you can tell in a line so this is like seats on a school bus everyone on the bus can hear the transmission but the message is only received by one specific recipient so a bust topology is an example of a multi-point connection right because we have it goes to all these different points there are many points connected to it if the message is for everyone on the bus so I'm meaning I want to send this message out to everyone that would be called a broadcast connection broadcast meaning it is intended and sent to every single person on the bus or every node uh on the network If the message on the other hand is meant to just go to one person or one node we're going to call that unicast uh finally if it's intended to go to more than one recipient but not all of them then we're looking at a multicast Okay so unicast as the name implies means one recipient multicast is two or more recipients and then I'm just going to write this up here broadcast as the name implies like a television broadcast it goes to all recipients on the network it's important to understand the difference in these types of messages we have broadcast messages go out to everyone unicast messages go out to one recipient multicast to two or more but different from broadcast because it's not going to everyone or all of them the way multicast works is that only uh the stations or the nodes that have subscribed to a message will receive it so we could if we're using a TV sort of example unicast would be like if you have a direct line to your sort of television provider multicast would be like HP only those subscribing to the specific uh cable network get access to it broadcast is sort of any it's in the air anyone can get it right so on a bust apology like we're looking at right now when the data is transmitted the signal will bounce or reflect off of the ends and so it's important uh that when the signal bounces it's gonna interrupt the transmission if there's nothing there to stop that bounce from occurring so to keep this from happening we generally have something called a terminator and it's generally around 50 ohms I would remember that for the exam because I do see that pop up and what this does is it really grounds the bus transmission or the bus connections to reduce uh and it reduces static electricity to keep this Bounce from occurring that bounce occurs then we're having all sorts of problems start to occur in our Network now uh if the way that these nodes are connected as you can see are by these T connectors and the reason they're called T connectors is because they look like an upside down t now the downside to using a bus connection are obviously these terminators and uh it's a little frustrating to sort of connect these up but the upside to using a bus technology uh topology rather is that it's inexpensive and it's relatively easy to implement now this is different from a physical star topology as you can see now instead of a line everything is connected to every other device using a central connection device such as a switch or a hub in a physical start topology where a switch is used what happens is the node that's transmitting the data to another node uh the switch actually will determine where that information needs to go and send it only to the node that is the intended recipient like a unicast right on the other hand a hub is going to send the data out to everyone and what's more like a broadcast connection now the uh and we'll talk more about hubs and switches a little bit later when we get to devices the physical start topology it's very common today and it's uh easy to implement and maintain and it's much more reliable than bust apologies because if one node fails or one connection to a node fails uh for instance this one then the rest of the network isn't affected and a sort of client server Arrangement each node is inherently not aware of all the other nodes on the network because the node only has a connection to this Central sort of host now the negative aspect of this physical start topology is we have what's called a single point of failure here in this connectivity device and if that fails all of the other devices won't be able to communicate so the benefit is now not everyone has to get the message and it's easier to uh it's sort of really cheap and easy to implement it's also the most popular because of any of these connections go down I don't lose connection to the whole thing unlike the bus where if one of those connections goes down obviously the connection can't continue but the downside is that I now have a single point of failure in this Central device now in a physical ring topology each node is connected directly to its upstream and its Downstream neighbors so if we're looking at this device we'll call it a those are the upstream and downstream neighbors it's much like water in an actual uh like River or stream the flow of data in the physical ring topology is unidirectional meaning it only goes in One Direction so the terms upstream and downstream are only used in the ring topology now here's the positive in using the ring topology because data is received and then re-transmitted from node to node the transmission is guaranteed to be strong and clear because each node is acting as a sort of like booster for the signal uh also because the data can only be transmitted unidirectionally in One Direction there's no collisions that are going to happen on the network in other words uh if this guy can't send data that way and then this guy's sending this data that way and then they sort of cancel each other out so we're going to eliminate uh you know where problems can occur and that's going to help administrators determine where an issue is occurring if they're having an issue with the network now negatively if one of these nodes goes down on the network the entire network potentially goes down as well and also because data can only transmit in One Direction there's a high potential for data to take a longer time to reach its destination because obviously if I want to send data to this guy but I'm unidirectional I actually have to go here then here then here whereas if I was using a star topology I could reduce that by one A variation by the way of this physical ring topology that attempts to correct some of the limitations is what's called a dual ring topology I'm just drawing that out and a dual ranked apology gives a sort of redundancy uh to the network by having a second ring either on the inside or the outside of the first ring and it allows data to flow in the opposite direction so this can double the speed of the network by sending data through the path that's going to be the shortest between nodes so if a wants to talk to C or actually we'll call that b just because of where it is and we'll call this one c um if a wants to talk to B it knows to take the blue line as opposed to the red line because the blue line is going to get it there faster so dual Rings also allow the network to continue to operate if one of these goes down which I think you could probably see from this so if the outside ring fails and the inside ring can actually pick up the slack for the outside ring a physical tree topology it's much like its namesake as as you can see it's a tree each branch of the tree can only receive its signal for from its parent node or its linked branch right so all of these can only receive a signal from this guy the root node is what we call the top portion of the network and it does not have a parent so it is the root just like a tree it's the roots it's directly connected to each of the child nodes that's what these would be called by a point-to-point connection now depending on how many levels you have here and we can see we have three levels here uh your tree topology is gonna have is gonna dictate what the what we call the branching factor is and this might be a little beyond the scope of the exam but I'm going to cover it here anyway the higher the branching Factor the longer it's going to take from data to go from one node through the network to the other because obviously if this needs to talk to this then right we're going to have quite a bit of data that it has to go through a positive aspect of this entire topology by the way is that because each level is connected only to its parent and its child nodes it's very easy to troubleshoot where the problems in the network occur because obviously if you're having a problem with you know this connection over here you know that none of these have anything to do with it it's also the other benefit is it's really scalable remember that word because obviously if I want to add another Network I can just add it either here or I can add another child here and then just sort of Branch off there now negatively if the connection should be interrupted or if a node that's sort of a higher level and the change should go down then all these subordinate nodes would suffer so if the connection between the root and their children goes down we're going to be in major issue because now none of these can talk obviously if this computer goes down then none of these will be able to talk to the rest of the network either so this is a a problem with it it is a variation by the way of the bus topology so again if the backbone fails then nothing else is going to work now with a physical mesh topology each node in the network is directly connected to every other node on the network so if we call this computer a you can see it's connected to B it's connected directly to C and it's also connected directly to D so for every computer on the network it's for every node on the network rather it's connected to every other node as a result because each connection is similar to like a point-to-point network uh communication between multiple nodes can happen at the same time and so it's very efficient highly reliable and has minimal data congestion because B and D can talk at the same time as a and C now for the same reason these types of topologies the mesh topologies are very difficult to manage and to maintain because each additional node that's added uh requires you to connect other you know every single other node to it so if I wanted to add an e for instance look at all of the connections I now have to add to this already existing Network so to alleviate some of the negatives of this type of network um it's uh we sometimes have what's called a partial mesh the partial mesh basically means only specific nodes on the network have to have direct links and this is sort of where we're going to go when we get into hybrid topologies it's going to limit the number of connections that are necessary throughout the network so a partial mesh topology would be useful if your network is comprised of say like end nodes that don't need a connection to all the other nodes on the network but it still allows high end devices to maintain the maximum transfer rates and the maximum amount of efficiency and reliability the internet's major divisions are connected to one another by a mesh topology so we're really going to see this in sort of large scale implementations that need High redundancy and efficiency I should add now a hybrid topology as we have we as we've discussed utilizes uh aspects of more than one type of individual topology so hybrid topologies are usually not created on purpose they're usually actually created out of necessity so topologies like this can maintain uh are difficult rather to maintain and to manage because each segment in the hybrid topology might have its own set of rules it needs to Follows the technology is on the different segments might not be the same either so I might have a different type type of Technology on this segment than I do on this segment and I might and then I have a different type of Technology on this segment right here so there are a few common types of star of topologies that are in a hybrid sort of breed that we come across this one's called a star bus obviously because we have stars here and then the stars are connected by a bus connection notice again the Terminators on either side we also have what's called a a star of stars hybrid you can see that each star is connected by another star so it's not only different topologies but when we connect the topologies together uh sort of in different ways that can be a different hyper topology as well and then another popular one is the star ring topology so similar to bus except there's no Terminators on the end because everything connects together you might also have a star dual ring topology which I have seen uh all the very infrequently by the way this one is also called although I doubt you'll see this snowflake topology now Network Protocols are the controlling factor and how all these topologies are going to transmit data and depending on the protocol data it might need to be transmitted to all the nodes on the network regardless of the physical connection so this is why having a logical topology is different from a physical topology in other words the way the data is transferred over the network might be different than the way the physical network is actually connected so let me give an example with this logical bus topology okay data is received by all nodes simultaneously even when the physical setup is different so for example we're using a logical bus topology with this physical star so the central device is receiving the transmission from let's say the sending node which is this one so let's say a is sending it out and then it's passing it to each node in succession in a continuous stream in other words it's doing this it's going down there and then it's sending it here and then it's sending it there and then it's sending it there and then it's sending it there so you can see what it's doing is although it's connected in a star physically the nodes are talking to one another as though they are logical now with a logical ring topology uh just like with a physical ring the data is only transmitted between its upstream and its Downstream neighbors so even though the star layout is physically laid out in a certain way the data from the transmitting devices is sent in specific order one to the next now actually most ring networks are physical Stars right so every time the data is sent it has to be sent to its up Downstream neighbor in succession like so so it just goes in a circular route we also have of course The Logical star topology which can utilize a central device and it's going to pull each node to see if it has the data to be transmitted so basically it says hey uh do you have any data you want to transmit okay do you have any data you want to transmit all right do you have any data oh you do great then it'll transmit that data and then come back around so the device ensures that each node has an opportunity to transmit but it also governs how long that's going to happen for and it's going to make sure that there's not any sort of problems or uh collisions with the data so just to recap what we just talked about albeit a a 5 000 foot overview of it we talked about topology which again is like how the network is arranged that Arrangement can either be physical meaning how it is physically connected or logical we then talked about a bus topology the bus topology meaning that it is connected to each device one in sequence we also need to terminate these with a 50 ohm Terminator on either side and remember we have a t connector that's connecting them we looked at a star topology which means that these are all connected through a central device a ring topology tree topology which has branches this might also be called by the way a hierarchical hierarchical topology and so on and then a mesh topology which would be every device connected to every other device and then we also looked at a hybrid of these most commonly we're going to see a physical star with a logical ring so it's important that as administrators we have an understanding of how the network is designed both physically and logically in other words how the data transmits over that physical stuff [Music] thank you Network hardware and media bounded Network media having discussed some of the basic terminology and some of the basic Network setups I want to get into now the hardware the media how this stuff actually physically connects to one another so we're going to discuss the different network hardware and media types in this module so the objectives that we're going to cover are first defining Network media and specifically bounded Network media bounded Network media meaning the stuff that you can hold bounded contained in chords and wires unlike unbounded which is Wireless we're then going to describe the different types of copper media and also explain the different types of STP that's shielded twisted pair and UTP unshielded twisted pair then we'll describe the different types of coaxial cable types and connectors and finally describe fiber optic median connectors fiber optics being that type of media that is that transmits data via light and photons rather than electricity over copper after that I want to explain the 568 a b and c standards which is how uh standard UTP and STP is cabled on one end and on the other so we can plug it in and finally explain something called premise wiring and structured cabling so Network media is simply the method or medium by which data will be transmitted it's further classified based on the hardware and Associated technology of the media itself now there are both wired and wireless Technologies associated with network media so in this one we're going to take a look at the first one wired Network media which is also characterized as bounded because it is bounded by a chord so bounded media is media that can be physically held there are a few types of bound media that we need to be familiar with we're going to look at either copper or Fiber now bounded Network media is the basic and original form of media and as administrators you're very likely if not guaranteed at some point to have to work with it in one form or another so having a solid understanding of the different types of bounded media will help you succeed in managing any type of network whether it's at your home a small office or even a very large corporate win or wide area network so the first type of bound Network media I want to go over is copper media copper media is the term used to describe any media that uses copper conductors as the method to transmit data in the form of electromagnetic energy so copper media can come in many different forms there are also many considerations that need to be taken into account when choosing between these different types of forms such as a distance the speed requirements of the network and of course the cost a lot of the time uh copper media was going to be fitted with some sort of shielding which also looks like braided metal wires or sometimes it looks like a metallic foil like you buy at the grocery store but it is a little different the shielding on the outside helps the cable prevent or helps prevent the cable from being uh subjected to what's called electromagnetic interference or Emi and of course if I allow Emi or electromagnetic interference to get into the copper within the cable then that's going to disrupt the sort of data that's going on inside of it now there are two uh different types of very common copper media that I want to go off uh uh specifically of coaxial or coax as shown here and twisted pair now twisted pair table is one of the most common cable types that you need to be familiar with depending on the specification of the cable and the type of twisted pair cable being used there's going to be anywhere from two to a hundred pairs or more now the pairs are color coded so the technicians know how to recable the cables on either end and it ensures that certain wiring standards and schemes are maintained in case another technician was to come in and start or end the work that you've already begun now all twisted pair cables are basically the same however it's how they are terminated that makes the biggest difference meaning how the end points so what happens at the end points now there are two typical types of standards that we need to be aware of these are uh t568 a and t568b so we're going to take a look at these right now now 568a it's less common than 568b today in today's networks but it's still necessary for you to know and you need to understand the difference between the two of these uh and it'll also help you in case you ever wanted to make a cable at home 568 a is wired in this way green white green orange white blue White Orange brown white brown now the only difference between the 568 a cabling standard and 568b is that the first two pins one and two are swapped with pins three and six that means that the orange colored wires are swapped with the green colored wires so then in 568b we see a wiring of orange white orange green white blue blue white green brown white and brown now the reason you need to know both of those is because of something called crossover cables which we'll talk about by switching those uh pins around it switches the data and how it's sent and we'll talk about the purpose of that a little bit later on but for now let's talk about something called STP or shielded twisted pair cabling which is a cable type that contains pairs of copper strands like we just looked at orange white and orange for instance being a pair that are twisted together and wrapped with a metal sheath or a kind of foil that decreases the cable susceptibility as we've already mentioned to Emi now because it's wrapped in its metal it makes the cable much more expensive than its counterpart UTP or unshielded twisted pair and it can make it more difficult therefore to manage or work with now although it has the shielding to prevent it from Emi it doesn't mean the cable is prevented completely from any sort of susceptibility it just reduces it I also want to mention the reason that we have that twisted pair each pair of cables for instance orange and white orange are twisted together is to reduce what we call crosstalk meaning that so that the data doesn't sort of jump between the two cables this was something that was actually discovered way back when when Edison was dealing with electricity now UTP or unshielded twisted pair cabling does not have that metal shielding around the Twisted pairs this is the only difference now this makes the cable much more susceptible to Emi than sdp however it's so inexpensive and so much easier to install and maneuver with and in most instances a lot of folks don't need the extra Emi protection so it's why it's one of the most common now there are several specific implementations of sdp and UDP and each one has different standards uh and characteristics and speeds and so on so let's take a look at those in a little more depth right now you may have heard of the or seen the terms CAT5 or category five or Cat6 or something similar to this before let's take a look at what these terms mean and what the specifications are regarding them because you'll need to know that for the exam cat simply stands for category there are both STP and UTP versions of these category cables that stand if you recall that's shielded and unshielded and the first category of cable is as you'd imagine category one cable now we don't really see this in the field anymore it's been superseded by the following categories cabling and but its original purpose was for voice I wouldn't worry about memorizing that one type 2 or Category 2 is rarely used today uh only in something called token based networks which we'll talk more about in the future but again it's not very common you're not really going to see it uh very much at all now Category 3 or ethernet which is different from the current ethernet but this was the first category established by an organization called Tia eia this is the Telecommunications industry Association Electronics Industries Alliance don't worry about memorizing that but in today's networks category three or cat 3 is used almost completely for voice Transmissions because it has a limited transfer speed of 10 megabits per second and a 16 megahertz bandwidth so a lot of telephone K old telephone cableing is cat 3. cat4 uh just like cat 2 it's not used anymore not even worth really spending time in now when we get to CAT5 this is sort of where we start really getting to Modern Day stuff Cat 5 cabling which is also called Fast ethernet provides performance of signals up to around 100 megabits per second important that you know this the maximum distance for CAT5 cabling is 100 meters or 328 feet now CAT5 e is the specification that superseded CAT5 and it addressed some of the weaknesses including uh crosstalk prevent prevention uh and other specifications in the like like CAT5 the maximum cable length of Cat5e is also 100 meters the bandwidth is also the same at 100 megahertz but it's said that data data rates can get up to about 350 megabits per second uh although sometimes an application that's not exactly what we see Cat6 is a standard uh that increased the transmission speeds quite a bit it's what's called gigabit Ethernet because it's rated for data rates of about one gigabit per second so we're going from again with 10 cat 3 from 10 Cat 5 100 Cat5e 350 theoretical and now we're at 1000 megabits per second or one gigabit per second the signal limb rate also of CAT5 Cat6 rather is tested at 250 megahertz uh but it's guaranteed at a 200. there was also another one after this called cat6a which was also known as augmented category six and it had a rating of a little bit more than a one gigabit but uh many people said that they can actually get to 10 gigabits and uh uh it's megahertz or frequency was also Higher by the way I wouldn't worry about any of the frequencies I'm just throwing those in there so that you know them what you really want to worry about is the data transfer speed a cat 7 which is one of the newest implementations uh it's not even fully recognized yet by Tia eia it's um also gigabit Ethernet and it supposedly supports a signaling rate of one gigahertz and has a potential for over 10 gigabits per second so you can see where we're we want to go there but at the same time Wireless technology or unbounded technology has taken us to a point where we might not need to spend as much time on some of the bounded media so now that we've seen all of these individually let's take a look at an easier breakdown of the specifics of all of these so as we can see here each of these cat standards has a maximum cable length of 100 meters for standard use and the frequencies and maximum data ranges go up with each of the standards as well in most cases when you're looking at the physical cable the exact specification is typically printed on the cable itself helping technicians ensure that the same standard is going to be used throughout the organization now while Cat 5 through 7 cables are very similar because they all use the RJ45 connector which is the connector at the end that plugs into your network card or into a port uh should a technician install a Cat5e cable and a cat 6 or higher Network the Network's still probably going to function correctly but the Network's only going to operate at the uh maximum speed of the lowest standard so if everyone else in the network has Cat6 and you install a Cat5e cable then you're limited now to the Cat5e um specifications now here's a picture of an RJ45 connector I want you to note there are eight pins which means there are uh four Twisted Pairs and next here's a picture of an rj11 which is used for phone lines and notice that this one has four pins so that's two Twisted Pairs and it's also much smaller than RJ45 this is what's used in what's called pots plain old telephone system or pstn the public switched telephone Network all right now moving on uh past cats uh and and twisted pair let's talk about coaxial cabling uh it gets its name by the way from uh this is sort of a fun fact common geometric access or common core because the shielding and the conductor share the same Center or axis as the name implies in common geometric access or axis surrounding the single copper core is a non-conducive meaning that it's not going to conduct electricity insulated coating which is typically uh some sort of dielectric insulator separating the core from the shielding the next layer after that is braided metal shielding and this could be either copper or steel sometimes it's a mesh of multiple Metals depends on the manufacturer the purpose of this shielding just as it was with the twisted pair is to protect the cable from Emi or electromagnetic interference it also allows the cable to be grounded and acts as sort of a drain when there is noise on the line we'll talk about noise in just a few minutes and also ways to prevent it the final layer on the coaxial cable as you can see is this outer sheathing or a plastic insulating jacket which just sort of keeps everything protected from the elements now there have been several types of coaxial cables used in networks over the past few years uh here's a breakdown of what you should be familiar with the first is what's called an rg58u it was used for ethernet networking actually if you see old network cards you'll actually see a a coaxial cable on them and it has a solid core and requires a 50 Ohm resistor it's about five millimeters thick this is different from the stuff that brings cable into your home and if you remember 50 ohm resistor that is what was used on a bust apology and that's why where we actually used most of these was on a bus topology now the rg58au is slightly different in that instead of having a solid cord it has what's called a stranded core which means there are multiple strands or cores at its Center as opposed to one solid one next and this one might be a little more we're going to get a little more into sums that you've probably seen is What's called the rg8 standard it was also used for ethernet networking but it's not seen very frequently today um because it's typically was used for backbone wiring and it's been which has largely been sort of superseded by fiber optics finally we have rg9 uh coaxial cables which are used with cable TV cable modem installations and so on it's about 10 millimeters thick which is twice the thickness of the original RG58 now we're getting into some others here that I wouldn't worry too much about for um the test but I just want to go over them since we're covering these anyway we have something called rg62 cabling which is utilized for uh something called an arcnet protocol uh networking it was a lan protocol uh commonly used in what was called microprocessing and then we have an rg59 cable which was used with low power which is used rather with low power video and receivers uh and it had also resistors and it was about six millimeters thick the RG6 cabling which is greatly preferred by the way over rg59 uh because it's more common is utilized for cable television signal routing and also requires uh 75 ohm resistors the term by the way thin net is in reference to ethernet networking that uses the rg58u or Au cabling these thin net cables coaxial and the reason they're called thin is because that thin five millimeter uh coaxial cable can be up to 185 meters in length which is quite different from the 100 meters we got with ethernet uh Twisted fare Network segments that utilized coaxial cabling have to be terminated at the ends like we've talked about to provide that signal Bounce from occurring they're terminated by installing that resistor that matches impedance uh that matches the impedance of the cable on the ends so as we've mentioned some of these are 50 ohms 60 Ohms on a a typical bus topology Network we're looking at 50 ohms now here's a visual of what the most common coaxial connectors are first we have a picture of a BNC connector with different types of resistors attached if we look closely at the top connector you can see the small needle at the center is just slightly bigger than the 50 ohm on the bottom this is important uh in case you have a 75 ohm which is plugged into a 50 ohm because there's going to be a potential of damaging the connector that's being received now this next picture is a shot of a t connector and a Terminator remember we talked about these when we were talking about bust apologies and when purchasing these you want to make sure you check that they're properly rated because uh you know every manufacturer has different color schemes and different types of uh ways of categorizing their terminators now moving away from copper cabling which is what twisted pair and coaxial is let's look at fiber optic cabling which is cable that uses pulses of light sent down glass or plastic core the components in fiber optic cables start out from the center working their way out so the inner strengthening Rod gives the cable its most most of its rigidity otherwise we would just sort of crack this stuff because it's very thin so we have something that's going to strengthen the rod and then the outside of the inner strengthening Rod there is filler compound in between the strands of cable at the center of these individual strands is the fiber core which is between 5 and 100 microns in a diameter and I don't know if you are familiar with that term Micron but that is very small that's roughly um slightly larger than like I think a human hair so just to give you a context there surrounding the glass or the core which might be made of plastic as well is what we call Core cladding which is responsible for trapping the light in the core and reflecting it in a particular way depending on the cable mode and on the outside of the course cladding there's a buffer that is color coded so a technician knows which strand they're working on next we have strengthening fibers that are typically made from very strong material and finally on the outside is an outer protective layer called the jacket the transmission method again utilizes pulses of light these lights can come from LEDs or light emitting diodes in cases where there is a slower Network or in network with a much faster connection we might even have a laser now there are different types of fiber modes and as an as a network plus administrator you need to be familiar with the different methods of transmission for each in single mode fiber only one single beam of light passes through the core now a bandwidth of up to about 30 megahertz megahertz can be reached and the signal is modulated by intensity to transmit data so the intensity determines the data with the next thing we look at is Step index multi-mode fiber the core of the fiber and the clouding surrounded it surrounding it rather have different indices by the way if you're not familiar with that word that's the plural for index of refraction if that's a little confusing that means that they have different densities which changes the speed and velocity of the light that travels through the medium so when the velocity changes it's called the step down this is why we have step index finally we have something called graded index multi-mode fiber this has a core glass a glass core rather that itself has differences in variations in the form and that allows for a large amount of bandwidth that reaches up to about two gigahertz now the thing I want you to remember most about single mode versus multi-mode I wouldn't worry so much about the graded index and step index but what you do want to remember is that single mode is good for longer distances but not as high transfer speeds multi-mode is good for short distances and uh higher transfer speeds think about it this way if I have a very large bus I'm going to be able to carry more people uh in a in a shorter distance if I have a sports car I might be able to carry one person or two people but we'll go a lot faster so you can think about it that way now St connectors or straight tip connectors are one of the most common you're going to see today they look very similar to the coaxial BNC connector and uh one way you can remember it is you have to twist them on and I think about that t for Twist the SC or otherwise known as a subscriber connector is also one of the most common connectors so you want to recognize that one as well we also have something called the LC connector which looks almost like an RJ45 type connector and it snaps in place it's also about half the size of an st and SC connector I also want to show you some of the other connectors that are listed on the outline although I don't see them much on the exam uh an mtrj or mechanical transfer register Jack which is also called a fiber Jack it's it's again just like the same size as an RJ45 and it's usually used to connect two strands of fiber together there's also a few other connectors uh FC which is face contact uh it's used in industrial environments uh it has a different Center that sort of gives it more strength there's also something in this this you will see is called fuddy or Fiber distributed data interface which can also be called uh mic or SMA or sub miniature assembly all these different names it's an older connector and it's uh one of the original connectors that was used now because of the different technologies that are available for networks today it may become necessary to go from one type of medium to the other in some of these cases we have to utilize what's called a media converter here are a couple common media converters you may have come across in certain networking environments now there are media converters that convert signals on fiber to coaxial cable when you're converting um multi-mode fiber into ethernet in order to extend the ethernet network over a fiber backbone we also have similar to multi-mode fiber there are also converters that go from single mode fiber to ethernet as well which is for the same purpose generally speaking we're going to see more multi-mode in the backbone environment because it's a shorter distance high high throughput lastly there's also something a single mode which converts to multi-mode fiber these connectors are generally used to extend the range of multi-mode signals now the Tia eia which we've already mentioned the organization telecommunications industry Association electronic Industries Association uh created standards for all this cabling that covers the proper implementation design and maintenance to ensure that there's a certain level of performance that's met and that's also going to ensure that if someone else comes into your environment they know what they're getting themselves into now there's six uh the standard is comprised into six different categories and it's important that you actually know these for the exam this by the way is called structured cabling so first we have something called entrance facilities and this covers the entrance of the Communication Service into the building and this includes What's called the demarcation point the demarcation point is that point at which the responsibility of the network changes from you to your ISP or from your isptu or your company it also contains the backbone connections as well next we have the backbone wiring which is the wiring connection that goes from the communications closet to the equipment rooms so the characteristic of this wiring is going to depend on the type of media chosen such as copper or Fiber but nonetheless we need to make sure it's it's very sturdy and also very fast the equipment room now uh so we've gone from uh dmarc to Backbone or uh we've gone from entrance facility or dmarc to Backbone to equipment the equipment room is the point of termination for the backbone wiring it's also called the MCC or the main cross contact and this can also be considered what I've seen it more considered on the network plus exam the MDF or the main distribution frame we're going to talk more about this shortly the next portion of structured cabling are the Telecommunications closets so these are contain the connection equipment for any of the nearby workstations as well as the connections between any Communications that cross-connect we also have something called horizontal wiring which is the cable and that goes between workstations and the Telecommunications closet and this is typically in the wall in the ceiling finally we have the work area which is everything coming from the wall outlet to the workstation so this is the face plate connectors wiring and so on so you can see that we're going from the sort of main point in our building that entrance where the D mark happens where the ISP the internet comes into our building all the way down to the workstation or the user the Tia eia has also set out a specification of standards that line out minimum performance levels for Network media in uh commercial environments now these standards are 568 a b and c we saw earlier the t568 A and B which were the standards for uh cabling colored Twisted Pairs and how they should be arranged and terminated but there are also some other specific attributes that you need to be aware of the 568a specification is an older standard it's governed uh it governed data voice video and commercial buildings and it's basically been outdated and superseded nowadays by 568a sorry B and C standards the B specification now is an earlier standard still in use quite frequently that defines minimum performance levels for cabling including twisted pair performance minimums uh shielded Twisted paramums fiber optic standards and Etc portions of this are now Obsolete and have been replaced by 568c the 568c standard which is the current specification that's set out designates minimums for optimizing Network media performance in commercial buildings currently it specifies cat 6A as the media type that is recommended so again the 568 A and B the T5 to 68 A and B that we saw earlier those are how everything is cabled those fall under the umbrella of the more General 568 a b and c standards which speak more to Performance now while the Tia and the eia have established uh standards for structured cabling premise wiring uh the terms that we're going to use are industry-wide so although there might be these standards the terms you're going to see over and over again hierarchical cabling is recognized and used which is what we're talking about when we talk about premise wiring everywhere it's a telecommunications design tradition that basically allows for main cross connects or MCCS to be connected to what are called iccs or intermediate cross connects in a star topology with horizontal cross connects in most cases you're probably going to see the terms wiring closet MDF or main distribution frame and IDF or intermediate distribution frame instead of MCC and ICC however they're both used interchangeably so I just want to take a look at some of the components that make up this premise wiring right now the patch panel is the connection point for drop cables and patch cables they're connected to the patch panel via the RJ45 connectors that we saw with twisted pair now you might find a patch cable with a single row of connections or one with a dozen or more rows now a drop cable what I just mentioned is the cable that goes from the workstation and the network devices to the wall a patch cable is a cable that is connected to the patch panel and connects two drop cables this cable might be either a normal straight through cable or a crossover cable which is something I mentioned earlier that crossover cable has one end that has the 568a wiring and the other end that has 568 B wiring this is in order to connect two like devices such as computers or switches directly to each other remember the pin out on these is different because the one and two pins are switched on one end with the three and six pins so this allows data to go directly between two devices a lot of devices nowadays however don't require the crossover cable uh because they have an auto sort of sensing feature within them now a patch panel and patch cables are located in wiring closets the IDF is the communications connection point or cable rack that connects all the workstations to the MDF or the main distribution frame the main distribution frame MDF is the main connection point or cable rack that distributes cables from itself to all the other idfs now there's only going to be one MDF but there can be many idfs the wiring closet is a room where the patch panels are installed and the wiring runs through it too so here we have a building where we have an MDF on the bottom floor and an IDF on each of the floors above the connections going from the idfs through the walls go to the workstations then there is a connection that's typically much faster than the rest of the network that goes between the idfs and the MDF when installing Cable in a building there are fire code requirements that have to be met specifically when you're running cable and air handling spaces which are like under floors and in walls most of the fire codes require a specific cable PVC cabling which is the typically standard network cable that's fairly inexpensive and easy to work with allows allows fire to travel through the cable if it berms and then it releases these poisonous and noxious fumes so as a result plenum grade cabling which is part of the uh plenum or a plenum space is part of a building that is used for air circulation and HVAC systems and so on by providing Pathways either that are heated conditioned or have return airflows space between the structural floor and the dropped ceiling or under a raised floor is what's called plenum so we have some special cabling called plenum cabling this is jacketing that's wrapped around the wires very tightly and it prevents fire from moving through it therefore it's not going to put off those noxious and poisonous fumes it also makes the cable a lot more expensive and it can be a lot difficult a lot more difficult to work with at times however it is required by fire code that if you're running cabling in between these spaces where there is no sort of sprinkler system to put out the fire that you use plenum grade cabling that's important all right so now let's go over what we learned first we defined Network media as well as what bounded media is we're going to talk about unbounded media a little bit later we also describe the different types of copper media including the different types of Stan shielded twisted pair and unshielded twisted pair and the difference between those remember shielded it protects from Emi unshielded does not and we discussed a few of the standards that are set by the Tia eia including 568 a b and c and remember that's we also have the 568 A and B wiring requirements which fall under these we also looked at the different connector types not only for the twisted pair which is that RJ45 but for coaxial like the BNC and fiber such as St or SC and we looked at structured cabling and premise wiring where we also talked about the differences and this is important between PVC cabling and plenum grade cabling [Music] welcome to module 2 lesson 1A straight through crossover and rollover cables we've actually covered some of this already in earlier lessons but what I've done is added upgrades for the new exam syllabus so consider some of it a refresher and um some of the new material so we're still under Network Hardware media bounded Network media a few of the objectives looking at modular connectors the t568a and B wiring schemes MDI and mdix straight through cables crossover cable and then Auto mdix which is a bit of a mouthful and uh another cable you'll be using regularly as a network engineer which is a rollover cable they've got different names actually they can be called console cables if you're working in the Cisco side of things we tend to call them rollover cables or flat cables but I'm sure you'll find out wherever you end up working what uh what they're called so modular connectors a type of electrical Electric electrical connector that's commonly used in the following systems we'll see these in a telephone systems data networks which is what we're more interested in as Network engineers low speed serial connections can also use them and now by the following names RJ which is short for registered Jack modular phone jack stroke plug uh Western Jack stroke plug just go back there you can see the port which is the interface that the module modular connector goes into and then the physical layer which will specify um a whole bunch of things like the voltage on the wire and how many wires and or teach wire is used for some of them are unused and um as the connections get uh quicker and the engine is worked out how to use spare air wires to increase speed which you'll see in a bit the male modular connector is known as a plug uh basically the cable um is terminated inside here normally you do buy these however um if you become a cabling engineer you can have your own tools to make your own network cables I did it for a while I can't say it was particularly um a lot of fun but it did pay pretty well a female modular connector is known as a Jack or socket used on fixed locations um such as on equipment uh example of the module modular connector is the 8 p8c connector uh I think Josh may have referred to that elsewhere but here we go here's a an image of one uh using ethernet computer network that uses the twisted pair cables for connection which is pretty much every Network now unless you went into some old basement um or some odd unit somewhere commonly referred to as RJ45 it resembles the connectors you'd have on many phones we have at home which uses an RJ 11 telephone cables But as time goes on these will all be changing and I think a lot of people don't really even use their home phones much anymore uh has nothing to do with the actual RJ45 standard looking at the um t568 A and B wiring schemes these are the specifications in more detail it's a four pair 100 ohm and shielded twisted their cable and usually terminated into an a position modular Jack now there's two wiring schemes five six eight a five six eight B this defines the pin out and the Order of the connections and this is very important we can't just connect any color cable um inside and attach them to any of the pins on them on the end there has to be a specific order depending on what we're trying to achieve you can obviously buy the cable it comes off um big rolls it could be a few hundred meters long and it's twisted into one two three four pairs there and they can be just untwisted slightly at the end and then the you can see the blue shielding there is normally inserted just enough so it um catches inside the Jack and then you've got a crimping tool which squeezes it onto the plastic connector on the end now we as I said we need to know which wire of the cable connects to which pin and which wiring standards we use the um t568 A and B standards govern the assignments of the wires so it says which wires go where now here's a graphic you can see and the pairs are put together with similar colors and then the specific colors allocated for each pin going from one to eight so um white and green green white and orange and blue white and blue orange white and brown and then Brown you can see different pins on the right because we've got a different standard yes and I've put on here which one's which so there's an interchange of green and orange wire pairs between the two different standards now I'll come to horizontal cables in a minute because [Music] um you don't actually hear this um term very often in Internet working and I hadn't heard of it for um until I come to put all the information together for the presentation but it's a recognized name even though it isn't used very often so the um 568b pin app became model used because it matched the older at T their pin outs and you can see the standard there widely used a new TP Cable in at the time and the infrastructure regulations and numbers were published just for your information you can research in your own time if you want but you can see a horizontal cabling in action here generally it's the cabling that runs between all the user devices the patch panels and the network switches now however you've got your network designs you'll normally group the switches together with what's known as backbone cabling so that's it in um image format there's a definition which I got from Wikipedia it can be the inside wiring or plenum Cable in connects your telecoms rooms to individual Outlets or work areas on the floor usually Through the Wire ways so this is the part of the cabling that you would normally um be concerned with as a network engineer and then um the core Cable in the backbone cabling May well be done by a cabling company it's not something that you would normally get involved in again it depends every networks a bit different and moving on to MDI and MDI X and devices on ethernet networks use two types of Hardware interfaces which I've already mentioned here the MDI it all stands for media and medium dependent interface so Hardware interface that establishes the direct physical and electrical connection with a UTP cable this is the traditional port on the back of a computer's network interface card an MDR device is a device with an MDI Port which kind of goes without saying I guess a computer or laptop um and this is a reference for specifications really I mean in all the years of networking I've never referred to a device as an MDI device and tend to discuss it more when we were using Hobs um in the earlier days of networking the mdix stands for um the MDI but with a crossover this is a crossover of the um medium dependent interface I'll show it up an image actually in a moment the thoughts of the devices that provide connectivity such as a switcher hover setup as a MDI with the crossover foreign so examples of the devices are switches or routers and I'll put in an image here to give you more um a frame of reference you can see here it's the front of an old fashioned Netgear maybe they don't even sell him anymore um Hub and you can see to the right there's a little black switch with a little line that connects to the number four now however you press that button it will act as an MDI or an mdix interface now if you wanted to connect that number four port to a PC you would leave it running in normal um mode you might be able to see the actual word normal it's a bit blurry this image so this is MDI and they're put normal because um You probably wouldn't be a network engineer using it at home or small office um the mdix they've designated as an Uplink that means you would connect it to another hub and so the it would change the way it connect and communicates using the different pin outs and it would act as if um you you're using a crossover cable which we'll come to later so this is basically what I've said it's going to um using the button you would um designate whether it's going to act as an MDI or an MDI X interface um this all basically changes how we use our transmit which is designated as TX and I'll receive which is designated as RX on the different wires and that's saying what that setting would do straight through cable the easiest way to think about straight through cable is um using dissimilar devices for example a um computer to a switch port a router to a switch and here's some examples also known as a patch cable in case anyone asks you to check a patch cable or get get them a patch cable I've mentioned UTP UTP cables they're used in the modern ethernet Networks and you can't directly connect unless you stay in the obvious I think you can't directly connect these wires to a computer's network interface card um if you want to be picky I suppose you could if you had a soldering iron and individually sold at each wire but that would just be a little bit of a desperation not somebody that doesn't really need to unplug so both ends are terminated with the 8phc connectors and you can see the two wiring types here using that AP AC connectors now the pins and the wire assignments are the same on both ends so we know this is a straight through cable or a patch cable the numbers match and well that's just a number into the pins the colors of the different wires inside match and that's you could tell you would hold the cable together if you didn't know if you wanted to see if it was the right kind of cable hold it up look at it and check that all the wire colors match now the worrying standards for the RJ45 is the um 568 amb they specify how to wire the actual connector over an Ethernet Network technically you could choose any order of colors you like if you were making your own cables and as long as it matched the other side then it would all work because the cables inside the the eight little wires are all exactly the same but um you wouldn't obviously be following the standards so maybe you could do it for your home network if you wanted to make your own cables but certainly not recommended for commercial Networks so only one of the following standards used for terminating ends of the UTP you could choose either and but I think I mentioned earlier the recommendations for the horizontal cables so the example of a straight through cable is computer or a server connecting into a switch port I've already mentioned that you wouldn't use both standards on them on your cable straight through cables are used when connecting to an MDR device or an ndi device to an mdix device and again we've seen this this is just zoomed in and giving you a better and detailed image of the cable type here if it's straight through UTB cable is terminated on both sides using the type a wiring then the a color scheme and should be so I'll say that again then the color scheme and the pin out the order of the connections will be shown in the diagram so this is the a standard and you do it a few times um for a few days and then you probably have it in your memory of what all data put the wires in again if it was you making the cables which um wouldn't only really happen if you were um a cabling engineer for a very large Network and there's the pin outs and the colors in more detail you can see the tip transmit and the um receive indications on either end there so when a computer uses pins one and two I have a pair of wise to transmit the switch will receive those data on the same pins when I sit when a switch transmits the data using pins three and six on a different pair of wires the computer will receive those so you can see here TX is going to an RX and vice versa um in the internet Network such as a 10 base t or 100 Base TX pins four and five of the blue pad and pin seven and eight of the brown pair are not used so technically you could have a cable that um doesn't um have connections on those pins there now you're more likely to be using a faster and connection type if possible so on the thousand base T ethernet cable such as cat5v all four pairs of wires will be used and that's how they get the faster speed but using the same cable types now the crossover cable you can see here is used to connect like to like so if you have two switches then you could connect them using a crossover cable two router ethernet ports you could use a crossover cable or if you had two PCS at home and you didn't want to pay for a switch you could also use a crossover cable used to connect the following MDI device to an MDI device you could also connect to um switches together as we have here in the diagram the MDI X device okay wiring for UTP crossover cable easiest way to remember is one goes to three and two goes to six everything else stays the same you can see that rule applies for both sides so left to right and right to left a crossover UTP cable has an eight pin modular connectors each end is terminated in the below manner okay so these devices will be transmitted on the same pins one and two these devices will also be receiving on the same pins three and six might be worth remembering that case that pops up in the exam which ones are receiving and which ones are transmitting foreign on one side is connected to pin three that's what I said and two to six terminating the crossover you would terminate by using the um 568 a wiring on one side and the B wiring on the other so using two different standards for either end um if we're on an end of the um cabling uses the a standard the other has to use the B that's if you're making the crossover cable Auto mdix it's Auto sensing so do you remember earlier we had this picture of a hub and you had to press this um the little switch on there while modern devices can actually Auto sense what type of cables attached and then change the designation for how it uses which wires on the eight pins on the inside and most modern ethernet devices for example switches use the auto MDI XV channel so it's pretty handy this is why sometimes you can plug the wrong cable into a switch and it all still works because it's got this automatic feature rollover cable is something you will have with you normally at all times as a network engineer in your briefcase and normally used to connect your PC or laptop to the console port on a router or switch and it lets you configure the device when you first buy it and it's blank or do emergency recovery for example if you've forgotten a password to configure the router or switch so it has a 8p AC connector rs232 based connector such as a DB9 this has actually changed now so you can see the DB9 connector your laptops don't actually come with DB9 connectors anymore it's pretty old-fashioned so what you'll do is you'll have a db92 USB connector um and you'll use one of your free um common connections using device manager to see which port to connect on so I mentioned Cisco console cables and recovering your Cisco router in order to you can make your own rollover cable roll over flat console same thing cable and the wires are basically reversed so every yr goes to the opposite number one goes to a two goes to seven three goes to six and um carry on with that number in so basically the whole thing's Twisted somewhere in the middle all right so we've covered modular connectors the A and B wiring schemes MDI and mdix straight through and crossover cable Auto mdix and brown leather cables so that's all we need to look at for now thanks for watching [Music] welcome to module 2 lesson 1B some more cables connectors and transceivers this is all new stuff that's landed into the network plus syllabus uh some of it's a little bit strange in as much as it's almost redundant and I'm guessing they want you to know this stuff in case you come across it in an environment for whatever reason all right so Network Hardware media and bound in network media a few things we'll be looking at copper connectors uh the stuff we haven't already looked at earlier by the way uh transceivers some termination points copper cable standards and network storage connection types so this is a used to be called uh d sub actually but it seems to have been hijacked into DB connectors but you can see the um the shape of the connector here is like the letter D really leave it on its side I like that so the theory is you can't uh plug it in the wrong way I say in theory because when I've run computer courses it might just be a Cisco thing because this looks a little bit thicker but the uh the Cisco um housing here I was so thin that the students would come and somehow managed to plug in the d-connector for the serial cables upside down now this did a couple of things it um a things don't work when they're upside down obviously with these tiny little pins they're much smaller than the ones you see here they actually got forced in the wrong way and all got bent like that so that actually cost me a lot of money it was quite a distressing when I started up my business so this is the theory behind the shape anyway I actually I don't know why I put into male and connectors here I want to do have one female but I put into male used to see these on the back of an old style PCS and um their laptops as well you don't really see them anymore because USBS have replaced all of it so you'd have to be looking at a fairly old machine they were created a long long time ago before I was born when my dad was a young man as he used to say 1952 exclusively by Canon and it looks like they've probably released a license so that people could use them they were used in toker ring networks I do remember those support I actually supported those for a while at Cisco although there was hardly any left it was pretty scary when somebody called in with a token ring issue external floppy drives if you remember those and you'd buy an old real old probably wasn't even a PC then it was a an Amiga or Commodore 64 or something and you could invest extra money to put these floppy drives in and if you wanted to load a game you probably have to individually insert uh I think it was around 10 floppy drives to upload each part of the program and I think I did have to do that for early versions of Microsoft Word or the equivalent I used in Mouse connectors also as I said eventually replaced by USB thank goodness the D shape so I've covered this already the theory is in fact I'm sure it works for most people I'll just give you a heads up there when I run Cisco it didn't work that way um I wanted the students to plug their own cables in to have their confidence but it kind of backfired a bit I designed to work with the eia tia232 serial interface standard I guess you should make it out of that for the exam sort of silly question would be asked the number DB whatever so uh what would DB9 or db25 this is supposed to refer to the amount of pins that are in the male and female part so it could be pretty hard to mix them up actually looking at them you more like to see the db25 on uh like a printer cable or something like that again if you see it at all now the F connector F-Type has been added to the syllabus not to be confused with fiber cables such as stlc SC which are covered elsewhere in the in the course here so it's a coaxial RF connector type used more commonly for cable satellite TV if you've got the back of a box you can see here there's a thread on the inside of the cable here and you'd have to turn it round and it'd lock in with the TR so you'd have to hopefully with enough finger pressure be able to secure it into place and then unscrew it those are when you need to TV antennas for those user on on using them your Broadband or Ethernet or whatever bandwidth could go up to several gigahertz uh punch down blocks this is a pretty tricky skill really and one that takes a bit of time but you can see here the cable has just been placed in between the runners and then the punch down tool has kind of got this shape as you can see here and this would force the cable in and the theory is it would strip back some of this uh coating for the wire and create a contact inside the punch down block takes a bit of skill and it's quite frustrating if you don't do it right or if someone hasn't used the correct tool it leads to this nightmare of intermittent connectivity that you'll have to go and troubleshoot you'll typically see this in inside a telephone switch um as switch mechanisms a couple wires punched down as I said the numbers are for these models are given uh 66 Block it's a model number so it doesn't mean the 66 connectors that particular one has 55 rows it was subject to crosstalk which is known uh quite known quite well in the industry had a reputation for that not suitable for high speed connections of 100 Meg or um or hayab now the 100 block replaced the 66 block so just remember the numbers here the 66 block hopefully they won't try and catch you out with the um question saying it's got 66 Connections in it's a model number just to confuse you often used the 100 is to terminate cable runs the fiber distribution plan and panel how to get images of this but I've I've got one that you can actually uh buy from the manufacturer this one obviously hasn't been set up at all it's a bare bone system that you would run all of the cables through here and then terminate so this is also known as the fiber Distribution Hub if you're searching for one to buy I think they give you different terms depending on which part of the country you're in or which country and at the bottom here I've got a URL for a particular company that sells them obviously speak to the sales advisor and find out what you need saves you um making expensive mistakes this is the patch panel used to terminate fiber optic cables access to the cables individual strands the so the strands inside the cable for cross connection now I do apologize for this however um it's in the syllabus now for some crazy reason previously we had um other RG standards I think it was rg9 or and RG58 I'll have to check you you can see it in earlier presentations anyway however now they've asked for RG6 and rg59 so I've highlighted what you need to do I suggest you make some notes as to um impedance which is all the same actually so it shouldn't be too easy um shielding here and then just make a note of what they've what they've said here so um RG6 uh Slash U what is used for the uq again this is just such a pain and it's silly because you'd if you're having anything to do with this you just check the documentation before you went on site it's very unlikely most Engineers if you asked most Network engineers and what can you tell me about rg59 Slash U there's probably not a lot they could say however I don't make the rules it's in the syllabus so just take notes and just chop that up to something you're gonna have to learn uh transceivers I've got some images here these are for um the SPF SPF plus and gbic which are connectors for Cisco equipment these um these would stand proud from the switch chassis and then this would be inserted in and make contact to the back of the chassis so here's the front of the chassis here here and you wouldn't actually see the back and there's this has got a nice thin slot that you would insert to yeah do the 3D version so transceiver is short for transmitter receiver as we mentioned earlier it converts the electrical signals from one type to another type so serial to Optical signals and vice versa The Cisco gigabit internet interface converter we call them gbx it's hot swappable so you pull it out push it back in again hot swappable here is very handy and I think we'll come to this later actually to find my cursor it means you don't have to power down your unit which is just absolute gold if you're working in a production Network because it's just horrible especially if you've got paying customers that are paying for 99.999 recurring up time and then you tell them you've got a power down the device they're connected to and just to swap out something so very handy plugs into the gigabit Ethernet port or slot SPF stands for small form factor pluggable I guess a gigabit interface converter that too is hot swappable bear in mind what you've got to do is check for bugs so if say for example you've got a Cisco device and you've read the documentation and it says hot swappable you ask them to do if you've got a contract a bug sweep for the say for example this with the model so say WC 36 whatever the model is you say I've got this switch this model uh it says it's hot swappable and just do a bug sweep this is I only tell you this because and this is the advantage of having someone like myself not that I'm boasting but I worked at Cisco and we had a customer who asked one of our Engineers if something was hot swappable the documentation said it was however um not that it was his fault there was a bug which he didn't know about and the customer hot swapped it brought down a core switch it caused a massive amount of problems there was I think some legal claims or whatever it's just headaches you don't need so if you've got the contract and just because it says hot swappable don't necessarily take that on face value and if you if you can log a ticket or do a search SPF plus is in the hearts version the hint is in the plus that supports higher data rates and this time up to 16 gigabits per second and then finally I don't have a picture here a quad small form factable a factor plugable and you've got different speeds just check the documentation on that I just wanted to um flag it up I think it's actually in the syllabus also uh so we've just got the ghibit module here and you can see the uh the chassis would actually be here so you wouldn't see all this typically and then you'd have obviously the slot here and I mentioned that only the the end bit would be proud and you've got two fiber cables in here I'm not sure what this model of the model is that it's actually plugging into we're just having a sneaky look here at the um circuit board is SPF plus and um yeah so just so you can see it working in an actual device and however you would set this up I'm not sure if this is um these have been linked together all the ones operating as a backup to the other so you can see what it would look like on a live environment and network storage fiber channel fiber channel ever ethernet it basically encapsulates fiber channel frames over ethernet it's a protocol in its own right and it was developed just specifically for this environment and you can see the um fiber channel over ethernet is working in this part of the connection here and then it looks like we've got ether channel here which um I don't think ether channel is specifically covered but we do um there's a part of the syllabus that covers um increase in Europe time I can't remember what it's called now let's say there's redundancy we do talk about later so uh it's a non-routable network protocol so it won't go whatever your connection is it wouldn't be carried out here to um to the internet it wouldn't work it'd be converted something would be converted to bgp or whatever you're using out here differs from Isco Z which runs over tcpip okay this is non-routable so that very much whether it would be working over tcpip and then just to tick the Box Infinity band it's added in the syllabus um there's a diagram here I got from melanox whoever they are just you could um see a topology of it working used in high performance Computing just think of exam questions basically why is it used it's high performance low latency so if it if it meets your requirements you'd consider using it uh direct or switched internet connection between servers or storage so it can be server to serve our server to storage all right so we covered a lot of ground but we're just topping up on what we uh already learned earlier you learn about some copper connector types transceivers so it'll convert one type of another one type of connection to another we talked about the the DB oops the DB M9 uh I think the other one was 25 the D connector and basically the shape is there hopefully so nobody plugs things in the wrong way that's any reason uh termination points copper cable standards which is the F standard I think we talked about which isn't fiber it could be fiber fibre depending on where you are and then the network storage connection type all right so that's all for now I'll look forward to seeing you on the next presentation [Music] foreign Network hardware and media unbounded Network media as we just discussed bounded media is that media error cabling that is bounded in the limits of a cable something you can hold unbounded media as the image here describes and the image right here describes is uh Wireless in nature meaning that there isn't any sort of chord that you have to rely on and therefore it allows for certain advantages and also certain disadvantages so we're going to look at the hardware and unbounded media types involved in these sort of connections so are the objectives for this module are to Define unbounded as opposed to bounded Network media we're also going to define the difference in radio networking and broadcast radio look at something called spread Spectrum which was created in order to help Wireless Technologies work more efficiently and effectively we're also going to look at IR or infrared or infrared connections Bluetooth connections and microwave connections all of these different types of unbounded media and devices and then we're going to look at something that most of you are probably more familiar with a wireless access point also a WAP then we're going to describe the characteristics of an SSID which many of you uh might know as the name of a network also called the service set identifier and finally we're going to look at the basic uh ways of properly installing an access point and by properly installing an access point of course we're referring to the network plus methodology of installing an access point all right so unbounded Network media is any network media that's not bound by a physical connection such as copper or wire a fiber that we've just seen the unbounded simply means it's wireless or it's using a sort of Wireless technology Now using unbounded media has some specific advantages such as it's easier to install and manage over its bounded counterparts because you don't have as much stuff to deal with in the same regard however unbounded Network media has the potential to be less secure than bounded and actually a lot of folks will say that there is no way to have a secure Wireless or unbounded network because traffic across the network can be intercepted a lot easier when it's wireless and anyone can just sort of tap in in radio networking data is transmitted as RF or radio frequency so one of the first forms of communications this these signals of RF waves were transmitted in the 10 kilohertz to uh one gigahertz range and in the U.S the FCC or the Federal Communications Commission regulates these radio Transmissions this kind of networking is unfortunately very susceptible to uh Emi or electromagnetic interference which we've seen previously especially from stuff like power lines metallic obstacles even atmospheric conditions some people tell me that they lose connectivity when a plane flies overhead a radio networking can also be very long range depending on the method of transmission the amount of power behind the signal the kind of antenna being used the portion of the frequency spectrum which is located in here that's being used now with broadcast radio which is also considered a broadcast network the signal is sent out in all directions and utilizes a single frequency for transmission so there's low power transmission for shorter distances is more common and is easy to install but there's also high power Transmissions which are used for further distances as you would imagine and it's difficult typically a little more difficult to install because it requires really specially trained technicians proper installation and maintenance techniques and so on with radio networking line of sight is not necessary which means that the uh this the device sending the signal in the device receiving the signal don't need to literally be able to see one another now because radio networking is sent over the airwaves uh the signal can be intercepted really easily and so in order to utilize the technology for day-to-day transmission of information we need to make sure that it's kept confidential and so a new form of radio transmission was developed this is called spread Spectrum a spread Spectrum was introduced to address some of the concerns that I've just mentioned uh it takes the radio signal to be transmitted and it sends it over more than one frequency so this makes it more difficult to intercept the data in transit now there are two different types of spread spectrums first is DSS or direct sequence spread Spectrum the direct sequence spread Spectrum that's a mouthful utilizes multiple channels to transmit the message simultaneously so it's going to use multiple channels and it's going to send that message all at the same time with DSS there's also a method of error checking and it's called edac which I don't think you'll see on the test which is error detection and correction and this allows for a certain degree of signal loss while still being able to put the original signal back together on the receiving end on the other hand we also have something called fhss or frequency hopping spread Spectrum in this method uh it sends the signal across one channel at a time and hops to the channel uh each Channel just just sort of hops to another one at a predetermined interval this method can hop from frequency to frequency anywhere from 50 to a several hundred uh different frequencies per second the sender and receiver as you can imagine need to be synchronized with one another and they also have to have the same uh set of frequencies to hop to which which is called a hop set this method of radio communication by the way is it's commonly used in the military because it has a fairly strong sense of security about it infrared or infrared which you might have heard of uh Transmissions are also unbounded forms of communication and the and the data is sent via pulses of infrared light hence the name infrared this light is ah between 300 gigahertz and 300 000 gigahertz range and in the in the electromagnetic spectrum of ranges and frequencies there are also a few types of ir that can be used um all of which need an absolutely unobstructed view between devices this means that they are what we call line of sight or loss because of this it nearly guarantees that there's a secure connection between the devices because they have to be so close to one another another example of infrared being used by the way is your remote control which is the reason that we probably found them on a lot of laptops now there are different types of infrared connections uh they're serial infrared which means that the data is sent in a Serial fashion uh in this case you're looking at probably around 115 kilobits per second then we also have fast infrared which goes up to four megabits per second and finally very fast infrared which gives you up to about 16 megabits per second so you can see that there is a uh the technology has changed quite a bit that being said we don't see this a lot in sort of um consumer markets just because it is uh because of the line of sight necessity of it now there's also Bluetooth Transmissions which is another form of short range wireless communication it's increasingly popular you've probably seen it with these sort of headsets and it uses a 2.4 gigahertz frequency which by the way is the same we're going to see with Wi-Fi and so that this can actually cause uh some interference with your at-home Wi-Fi network now today Bluetooth is used to connect devices like headsets cell phones uh laptops mice gaming consoles um so on and so forth the accepted maximum range of Bluetooth communication is about 30 feet uh which is equivalent to around 10 meters but the newest implementation Bluetooth 2.0 is said to reach up to 30 meters or a hundred feet uh but it's not guaranteed to run that distance and um in application it might not actually get there now when you're connecting devices by bluetooth we call it pairing devices uh and if you've never done this before generally there's a pin code that's used to pin these a pair these devices together to make sure that they are secure and you're not connecting to a different device the next type of uh Wireless transmission I want to talk about is microwave transmission is the same term for that thing in your house the microwave operates in one one gigahertz to 300 gigahertz frequency range and for the microwave transmission to be received successfully there has to be an unobstructed view or point-to-point line of communication so just imagine that the satellite uh for your television for instance if our satellite dish at home doesn't have a clear line to the satellite in the sky we see that it's signal to grade or drop off altogether so obstructions such as buildings uh trees even atmospheric conditions like rain Etc can all play a major factor in microwave Transmissions one of the greatest benefits of microwave Transmissions is it has a really long range of communication as you can imagine uh uh your satellite at home can reach all the way up to the sky and hit that uh satellite in the sky or rather your receiver at home or your dish at home can reach that satellite in the sky and so there's a real strong benefit to the satellite microwave Transmissions now the one you're probably most familiar with here is a wireless access point which is a radio uh a type of radio frequency device it allows wireless devices to connect to a network it has a network interface that allows it to connect to a wired Network as well so generally speaking this would go off to say a switch or a router now how do we know which wireless access point we want to connect to this is something this is where we get into something called an SSID and there are also other settings that we need to take care of when we're setting one of these up so first let's talk about the SSID or service set identifier which is a up to a 32-bit alphanumeric string and it identifies the name of your wireless access point so in some ways we might call this the name of your network right out of the box when you just set it up the access point is going to do what we call broadcast your SSID this means that it's transmitting the name of the network uh into clear text so that anyone who's within range can see it if you live in a building or if you're in an office space you've probably seen this so This creates a vulnerability on the network especially if you want to limit the number of users that are trying to access your network so with your wireless access point there are a few steps to make to ensure that we're going to install this correctly uh safely and efficiently so the first thing we want to do is to choose the proper device for your needs obviously there are different types of access points if you were around for a plus we talked about what are called Soho routers or Soho access points which also have routers in them but an access point simply is the device that's connecting you wirelessly to your network now if you have a corporate environment or a home office Network you're going to need different things so the next thing one once you've decided which device you want we then have to talk about where we want to place it and specifically we need to ensure that our users can access the network from all the places they need to which is just as important as considering which users we don't want to be able to connect so we want to be able to place it in a place that is of course Central but also is limiting or Limited in the amount of people who are going to connect to it if you put it near a window for instance our next door neighbor might be able to connect now almost immediately after bringing the whapper the wireless access point out of the box we want to change the administrative default password so and disable any guest accounts this means that all these settings that we're talking about uh you need a password to be able to get in and change them so we want to change that or disable the guest account change that and we also want to make sure there are no other backdoor accounts um you can generally check in your administrative sort of um manual to see if there's anything like that so that way we don't have any unauthorized access to the account next thing we want to do is configure these wireless access point settings including the SSID what encryption we're using power and so on we'll talk about encryption and in further detail in later uh lessons so don't worry about that so much right now figurations have been set we also want to disable as we've mentioned the SSID this doesn't mean that users aren't going to be able to connect to the network by the way it just means that if you're looking for available wireless networks it's not going to be uh broadcast out there so in other words you need to know the name in order to find it it's sort of like a door that's hidden in the wall if you know where the door is you can find it if not it Just Blends into the wall finally after we've set everything up the last thing we want to do is test for functionality make sure that all the users can connect make sure that they can get in from the locations they need to and also make sure that people who can't who shouldn't be able to connect can't all right so now we've talked about a couple different things first we talked about unbounded Network media which again is sort of Wireless in scope it means there's no chord we looked at Radio networking and broadcast radio we also looked at the sped spread spectrum and if you remember that's we have two different types one which is going to broadcast on several different channels on the Spectrum at once and one which hops around at certain intervals we also looked at infrared Bluetooth and microwave connections these two much more uh shorter distances microwave a much longer distance this requires a line of sight so does IR Bluetooth does not but does have a very limited degree of um distance that it'll work we also looked at a wireless access point or a WAP by the way wireless access point is also going to be built into what's called a Soho router those are those Linksys or Netgear routers that you buy at the store and finally we described the characteristics of an SSID specifically the fact that we want to disable their broadcasting so we've talked about the bounded and Unbound media let's talk about some of the devices this media is going to connect to [Music] Network hardware and media network connectivity devices so having discussed the way that devices connect either using unbounded or bounded media let's now talk about the connectivity devices themselves so the objectives of this module are first to Define and describe a Nick which also stands for a network interface card this is the main way in which devices connect to a network we're also going to talk about a transceiver a chip that is on the Nick and basically allows it to communicate we're also going to identify the characteristics that make a switch one of the main Central devices in our start apology that allows for communication on a local area network and then we're going to identify some of the qualities and some of the characteristics that we can put into a switch including trunking Port mirroring and channel bonding all of these do come up on the exam and so they are pretty important to cover then we're going to talk about a router and a Gateway these two devices allow us to communicate outside of our local networks onto a wide area network or a Wan now as with anything we have noise that interrupts the signal and so we're going to talk about what that noise is and the sources of that noise so we can better uh alleviate and avoid it finally we're going to talk about that alleviation and avoidance by talking about noise control and reduction techniques sometimes getting into these specifics of how this works now some of this might be a little too complex for the network plus exam but it's good to go over anyway so you have a firm basis in the theory behind it so the Nick or the network interface card is a physical connectivity device that can be either wired or Wireless for Wired networks the Nix gonna have an ethernet port which is right here that allows you to connect to an RJ45 cable if you recall the RJ45 cable is the ones used with most uh twisted pair installations you can either connect it directly to the motherboard or it can be connected through another card or a riser card or an expansion bus as this one would be now there are typically connectivity lights uh on the outside of the Nic that allow administrators to get a a quick status of the network connection the connectivity lights can mean different things depending on the manufacture of the Nick however most commonly there are going to be at least two and possibly even three and each of those lights are going to be different colors you can see on this one we have three different lights there should be one light that is on to dictate that there is a connection that would be a solid green light most of the time and it's going to stay lit when connection and there's also going to be another light that's sort of going to flicker the flicker is letting you know that there is activity or that traffic is being sent across the neck the faster the flicker uh typically this means that the higher the network speed or the more data that's going over occasionally you might see one with different colored lights the different colors might dictate for instance the speed of the connection for instance a green for gigabit speeds which would be a thousand megabits per second and Amber for instance for uh 100 megabit speed across the network okay and this is going to really vary depending on the Nick it's also important to know that the MAC address which might be written out here is actually hardwired or hard uh coded into the neck so it's something that comes with the Nick itself now a transceiver is a Connect every device that has the ability to send transmit or receive traffic simultaneously the ability that this has is special is due to a specialized chip that's right here and this assists the Nick in transmitting traffic across the medium almost every modern Nic has a transceiver built directly on to the device now a great example of a transceiver at work is something called the gbic or gigabit interface converter this is something that allows the conversion of electrical signals into Optical signals and then back again the gbit can also be used to convert different Optical Technologies from one to the other and this the benefit of this is it allows a network to be upgraded without actually having to upgrade all of the components so if we're going to be using for instance fiber optics and copper on the same network this is something that we're really going to want I wouldn't worry too much about transceivers for the network plus exam but I did want to cover them because they are listed on the um uh on the outline and as I mentioned they're really built onto a Nick so it's sort of a subset of a Nick something that is on the Nick that allows it to transmit and receive that data and also allows it to convert sometimes those signals from one into the other so this is how a computer is going to connect let's talk about switches a switch is a connectivity device that connects multiple nodes together acting as the common Connecting Point if you think back to our start topology we have all the nodes connected in this way now the switch looks at something called the MAC address or that physical address that's burned onto the uh uh Nick it's a 48 bit hexadecimal address and we will talk more about it later and what it does is it looks at the MAC address of each packet of data to ensure the data goes to the proper destination or to the node for which it is meant now because of this because the switch looks at the MAC address of each packet it ensures that traffic is only going to the intended recipient a managed switch just going to write that in here is a switch that allows an administrator access to its configuration and is able to be monitored now the way that this works is that there's generally something called a console port on the back of the device and you use something called a console cable in order to access this depending on the manufacture of the switch this might be light blue for instance in Cisco switches which is generally the most common and sometimes you might have light yellow or orange for others now switch is forward traffic to destination nodes via these ports on the switch and there might be as little as uh you know a few ports maybe eight four or even up to 168 or more now administrators have the ability to do a couple different things the first thing they can do is do something called Port mirroring Port mirroring effectively as the name implies takes all the traffic on a specified port and replicates it or copies it to another port now this is used for monitoring for instance if I want to see what's going on in a port but I don't want to stop the traffic I can monitor this traffic for analysis and diagnostic purposes it's also going to allow administrators to diagnose whether traffic across the port is being interfered with by a nefarious individual or someone who's has a malicious intent such as a hacker now if administrators want to combine two or more network connections it's called link aggregation or Port teaming and there are other names as well what this does is this serves to increase or effectively double the bandwidth uh as well as allow for some redundancy obviously or a backup connection or something else another name you might see this as by the way is trunking so that's the one I most see on the exam so that's again taking two and sort of treating them as one finally we have something called Channel bonding which is the process of adding multiple Nicks to one Mac address this is also called Nick bonding and we'll discuss it in Greater detail when we're talking about IP addresses and some of the other protocols as opposed to a switch a router is a connectivity device that typically connects multiple networks or network segments and unlike the switch it looks at the IP address of each packet of data to forward the to the destination node so instead of the MAC address uh we're looking at the IP address now a router is usually used to connect networks that use the same routable protocols so a routable protocol is any protocol that identifies the node versus the network using addressing I.E the IP address now a router can be installed as a hardware device as a function of a multi-function device like a Soho router and uh it's also can be installed as software in another device in a virtual environment for instance on a server in the case of a router being installed as software in a virtual environment the device or node has to have two Nicks one Nick for the note itself and then one Nick for the routing functions sort of like one to go in and one to go out a Gateway is a connectivity device that's very much like a router in the way it functions and it routes traffic in much the same way but the difference between a Gateway and a router is that a Gateway connects networks that have different protocols or dissimilar protocols that to communicate so the Gateway performs the translation between incompatible networks uh I'm just going to put translation here since I think that's pretty important or even different uh email systems or operating systems now although it can be easy to confuse a Gateway with the default gateway that we see when we do an ipconfig it's not the same thing a Gateway is a device on the edge of the network that's used to convert traffic between different systems while as this default gateway is simply forwards data packets in TCP so we're going to discuss that in more detail later but I just want to point out this is not the default gateway and just like a router by the way it can be a hardware device or software within a router or on another virtual device and it uses radical protocols that are similar to a router but again it allows the translation between different types of protocols now let's look at virtualization a bit since this is really the the big thing in Computing nowadays a virtual switch for instance functions just like a physical switch you cannot however directly communicate between two virtual switches if you want to do that you need a virtual router or a router now a Virtual Router is the software that can be installed on a device with two nics for routing traffic a virtual server is a server that operates independently of its host machine meaning that it's all software based CPU Ram Etc can be independent of its host machine whatever that might be now virtual machines uh are similar to a virtual server in that it has its own software like uh CPA based sorry software based CPU Ram Nic hard drive Etc but it's a software implementation of a machine that performs specific tasks and executes specific commands but it's not a server per se all right remember a server or something that's serving up information to a client and then finally we have a virtual desktop which in Windows systems is a single desktop which in Windows systems a single desktop is the default that can be open but a virtual desktop allows you to open multiple different desktops at the same time Linux also supports this by the way but Microsoft requires extra software that you install for this to be changed for instance uh virtual PC we've seen this if you remember with um an A plus with XP Mode now continuing to talk about virtualization if an organization or a company builds their Network infrastructure and chooses not to use it they can lease it out to others so for instance Amazon would be a great example of this they have a huge infrastructure but they don't use all of it so what do they do they lease it out to others this is a very common practice and what it's labeled as is networking as a service now an area of network as a service or Naas depending on what is being leased might be considered one of several different things it might be considered IAS or infrastructure as a service meaning like the hardware I provide you the hardware provide you the infrastructure it could be software as a service much like Gmail which simply provides you certain software and just like infrastructure would be like Amazon's uh ec2 or elastic cloud and then the last one is platform as a service which would be like a an application sort of engine or uh allowing you to deploy certain development tools most of the time you're gonna see most of these in the field this one is really more for Developers so the term Legacy indicates that this is a an older device one that's not really in use in today's networks or that have been replaced by a newer or higher functioning devices so some of the things we're going to talk about in this one might appear on the exam and the reason the reason for that is because they might appear in the field uh just because they haven't been replaced yet by perhaps due to expense or something however these have probably been replaced by switches routers and gateways but it's still good to go over them anyway so a repeater is a simple device that does not look at the traffic at all all it does is it simply boosts the signal after it receives it and transmits it out so it just repeats the signal as the name implies just boosting that signal we also have something called a hub which you might have heard of and this is similar to a repeater in that it only it doesn't look at the data it just retransmits it but the thing that a Hub does is it receives traffic from one port and sends it out to all the ports without looking at the data traffic now it's vastly been replaced by switches because as you can imagine if I wanted to send data to only one node The Hub doesn't allow me to do that it makes me send it to all of the nodes and so this is going to cause quite a bit of extra traffic on my network finally there's something called a bridge which was the purpose was to divide logical bus networks into segments and it did this by looking at the MAC address so it is operating it's sort of the same level as a as a switch and it would look at the MAC address of the packet and transmitted the data accordingly now if the MAC address was on another segment it forwarded it out and if the destination was on the same segment then it didn't forward it so in older networks this implementation was logical and it was handy because it reduced traffic congestion and improved performance obviously because it wasn't forwarding data that didn't need to be forwarded on all right now let's talk about noise noise or electrical noise and networking it's the term that interferes with uh implies rather interfering with data uh and normal data traffic it can come from many sources and as Network administrators it's really important that we know where all this noise is coming from and how to prevent it as well so not only can noise affect our network uh performance but it can also affect data transmission electrical current as well now if electrical current is interrupted or interfered with then that can affect our electrical devices so for instance if there is a surge in the current that means a lot of extraneous noise in the electrical line goes to our devices and then damages them so sources of noise are found in many places as you see here is a power line electric motors used in HVAC systems elevators refrigerators just about anything that draws power to run fluorescent lights neon or height intensity discharge lights or what are called HID lights uh also cause significant amounts of noise that interfere with networking over both bounded and unbounded media this is especially important to be mindful of when you're running or installing your cables or placing your wireless access points you want to really avoid running data cable parallel to those lights as well as any cables used for power it can also come from devices that give off heat like personal heating devices and while that might sound a little strange it's due to the amount of power that those devices consume when in use the power or the electricity it has the potential to give off a lot of noise which makes sense now lastly normal ambient noise also called background noise or the noise that's present due to atmospheric conditions like solar disturbances radio broadcasting towers that are nearby Etc the main thing to consider with ambient noise is the distance or the the length of your media the longer your media run is the closer to its maximum rated length then the more susceptible your signal is going to be so to combat this we one thing we can do is called grounding which is a method of taking the shielding or a conductor and connecting it to an electrical ground point that is directly in content with literally the Earth's ground now when we connect a network segment at one point to a ground this basically shunts or drains the extraneous noise only leaving the data signal so at the same time if more than one point is grounded this can introduce even more noise which is going to greatly reduce the quality of the signal if not even completely get rid of it so we can only we only want to uh ground the point uh once which is important if we do it more than once we're going to be in major trouble not only do we ground for Network for a performer but we also do it for safety because most electrical devices have to be grounded in one way or the other otherwise you know we just like we saw with a plus and touching devices if we don't ground something we could possibly damage it this is mostly to redirect uh High voltages into the ground where they're not going to harm your equipment now electricians have special ground points or dedicated ground points that are designed specifically for sensitive electrical equipment these isolated grounds they're def they're usually going to be colored orange which helps differentiate them from normal plugs so if you see an orange looking plug that is a special uh isolated ground now the shielding around a cable as you can see here on this coaxial cable um is a noise prevention measure that takes the noise and drains it through the shielding away from the conductor in the center that is carrying the draining the the data traffic now the shielding is then connected to a single ground Point flushing the noise away the connection between the shield and the ground point is also called the drain which is why we say it's grain drain and this same thing doesn't just go for coaxial it also goes for STP or shielded twisted pair as well now because the noise is often going to be constant the method of differential signaling takes two received signals and subtracts the equal signals which is typically going to be the noise of the noise floor and that's going to give us an end result of Simply the noise so basically it takes this signal input which is a digital input signal and it takes that subtracts this and then we can get a a signal without any noise in it as you can see now besides differential signaling there are also a few other noise control considerations we talked about earlier something called termination which is really important in networking some cables require termination to be installed at the end of either uh the end of either connection right if you remember that from our bus and it has to have the appropriate ohm rating if you install the Terminator and it doesn't have that proper ohm rating then it's probably going to um uh actually it won't work effectively now luckily for us in most cases the Terminators are installed in these network devices by default but not too long ago you had to install them manually and you had to make sure the impedance or the amount of ohms was matched it was a fairly simple task but the specific impedance could have been marked on a cable jacket or if a large amount of cable was installed it just added another step to the process now something else to keep in mind is how you run the cable your cable run you don't want to run data cable and electrical cable in the same tray and you should try to avoid running your data cable parallel to any electrical cables or any other data cables in order to reduce what's called a crosstalk which basically means the signal sort of jumps from one to the other now if you keep data cables away from Motors fluorescent lighting high power devices like we saw you owe and you always ground your electrical equipment and electrical circuits according to the manufacturer and you allow for uh all the recommended installation requirements and grounding requirements that they provide then you should be good to go when you're connecting your cables together and when you're um running your cables as well so just to recap what we've talked about here first we looked at a Nick and a network or a network interface card foreign we describe the transceiver something that goes on the card and how it functions we also looked at identifying the characteristics of a switch which if you remember use Mac addressing we defined trunking Port mirroring and channel bonding remember trunking was using two or more ports as though they were one port mirroring usually going to use for Diagnostic purposes and then Channel bonding which is uh sort of bonding those Nicks together we also described a router and a Gateway which again operate with IP addresses instead of Max and they allow us whereas switches allow us to work within a lan IP addresses or rather routers allow us and gateways to operate within a Wan or a wide area network finally we looked at some Legacy devices and we defined noise and the sources of noise including any of those high power devices and then we looked at some noise control and reduction techniques including proper grounding and shielding [Music] so welcome to module 2 lesson 4 new topic added to the CompTIA syllabus the um what is the syllabus number the below seven um Advanced networking devices so this is stuff that we need to be aware of because it becomes a prominence may have been in the industry a while but um now in regular use or big ubiquitous as they say so Advanced networking devices Network Hardware media I'm going to look at multi-layer switches wireless controllers a load balancer IDs and IPS we're going to look at AAA and radio server I think that's dotted throughout the syllabus so we pick it up as a security subject and also an advanced networking device uh UTM Next Generation firewalls Veep Gateway and in terms of PBX that is uh content filter so this is one of the I think it's the first device actually that Cisco ever um brought to Market is known as the um the Cisco pretty hard to see there it was the AGS uh husband and wife uh first artist Cisco and I think they had a colleague that they used to work with and um they actually bought um the first Cisco switch was actually created by a company called a kaplana or kalpana if you pronounce it this was their very first ever switch and um switches used to run some old uh code I think something like um I think we used to call it katos and then the routers well there was no code um that they because they created it they created their own code and that's called the internet work operating system Cisco brought the whole thing together now so there's this you don't have to use the old command line that work for katos but they they just weren't compatible at all so you had to kind of learn how to program two different type of devices so this was the early I think this is from The Cisco Museum actually and um you can see the Cabana switch up here so a real old-fashioned connectors uh maybe the db25s you can see there's no high speed connections here massive switch and then your power connector yeah so I'm sure this is Cutting Edge when it first came out huge thing in the 1990s but when you're supporting networks back then really um there wasn't an awful lot to it a server router a hub there wasn't that much traffic because people couldn't afford the kit anyway um early 90s the web was invented I'm sure most people weren't really using it ethernet was running at 10 Meg half duplex a Cisco the early 90s had 251 employees obviously there were just I think three people to start and they grew to 251. and then scroll forwards to the current ERA and you can see obviously things are a lot more complicated we have a multi-lay devices working at seven different layers of the OSI model incorporate Wireless into our Networks recover Wireless later there isn't anywhere you go now really where there isn't somebody offering some sort of wireless connection virtualization is a Hot Topic and it's obviously used by pretty much all of the cloud providers Amazon Google and Microsoft to um cut costs and improve performance cloud computing is a red hot topic that I encourage everyone to learn video voice over IP and quality of service you need to be aware of advanced security threats and obviously the larger the network now they'll have their own dedicated security team for Hardware software and um protecting from employees and that kind of thing Cisco currently has 72 000 employees I know when I worked there when was it the early 90s they were getting rid of slaves of different employees from the legal team and marketing teams and some Engineers as well so I'm not sure if it was ever higher than that but as stated on the interweb it's 72 000. this is quite a lot so what are the devices that's mentioned now brought into the syllabus is the multi-layer switch switch is generally a layer two switch is which is the cheaper models will switch frames at Layer Two and they'll lay they'll use hardware for this multi-layer switches operate layers two to seven you can buy a switch operates at layers two three four or another switch and you can see here I might be clear but the this is actually uh a connection bracket here and what happens is this is a switch in module that you can buy and Slot into the chassis so what you could have there instead is uh there's two um modules here and depending on what you buy you could have one here for voice one here for remote connections you could have a mini switching module here or one that's only dedicated for voice connections you can see actually these are exactly the same and it looks like there's USB there if you um connect in management interfaces a console connection and there's what there's one two three four switching modules here and it looks like it's got Quad Power as well so if anything goes wrong with the power supplies you've got three uh possible power supplies I'm not sure they're probably going to be hot swappable and I'm not sure if they're working uh there's one's a backup four two and um fours are back up for three and vice versa you have to check the documentation but this whole chassis would obviously be connected into the cabinet here and you can probably have um one major switch here and then a second one to take up um the whole rack so multi-layer switches operate multiple layers from two to seven bandwidth can be up to several gigahertz and you can stack Cisco switches so they all become one you could have two or three switches or becoming one logical switch and ports can be switched which is Mac address a MAC address in or you can configure them to be a layer 3 port and Route IP addresses and I think that's outside the syllabus how to actually configure it um so this would be your typical layer 2 switch now if you wanted to uh route so if these devices down here on VLAN 20 you can see they're on 192.168.20 well that's not a different subnet to one on two one six eight ten so this would be host uh one and two for example on that subnet and this would be host one and two on that subnet well the only way because this is working at Layer Two the only way to Route because we're we're dealing with layer two layer 3 here and so all layer 2 traffic this switch would take care of in its Mac table which we've covered earlier now if you wanted a route then um traditionally you would have to send out the packet to the router the router has a directory of all the networks 10 20. this network 30 will probably be for foreign management traffic or it could be whatever you want and then it would route and then it would decide that it needs to send that traffic out it could be an interface or a sub interface this is uh what's known as a router on a stick one armed router or router on a stick and unfortunately they have the physical cable uh will carry all the traffic coming in and out not a great way to run your network I mean it's okay if you're in a small business and nobody would notice but this is carrying all your bandwidth and obviously this is a um single point of failure here this cable breaks all this interface or this interface then you can't Route traffic the only traffic that would then pass would be um with it within the um VLAN sorry uh he couldn't be couldn't pass this traffic so this is a multi-layer switch so call it um say layer 3 switch and what happens is as you've seen you've got the modules that are slotted in here the more you pay the more options you have obviously and this module here is for switching so you've got all your ethernet connections and this could be your routing module and so all contained within the same chassis and the technology isn't really covered in the syllabus but it would switch the uh traffic depending if it's Layer Two or layer 3 within the same unit so basically what you don't have to have is this device here and this device here it's all within the same unit and depending on what you spend this could be um doing access lists on also your connection out to the internet depending on how how much money you have and what your requirements are uh next device is a wireless controller this is a Cisco 2500 Cisco wireless controller has the cheaper devices you've probably seen you probably got one at home here is your wireless access points and what happens is you've got a few um wireless access points probably say this is your office and normally these would take care of all of the connections what happens is these become lightweight access points in as much as all they're doing is taking in all of the signals and then passing it over to this master device obviously it costs a bit more and so these are lightwork access points and this is your wireless LAN controller which some people refer to as wlc so it allows your wireless devices to communicate and you can see you've got some wired connections there as well takes over from the access points becoming lightweight forwarders so you'd have to throw them away which is Handy the wireless access controller has your service set ID it can have logical interfaces and as you can see down here you've got physical pause for ethernet and when you first buy it if you want to you can connect to the console Port here and then use your PC to set it up to whatever um parameters you want and also you can use this port here for Disaster Recovery you obviously have to be physically present unless you connect a Cisco access server which we'll cover later which um that would have an internet connection out here so you could um and if you said tile Nets probably ssh in through um here and then you could from the from this um Cisco access over here you would have a connection going into your console Port but we'll cover that later uh ports can be switched uh so they're just dealing with Mac addresses or they can be configured to route depending on what you need so your wireless controllers these your wireless LAN controllers permit mobile devices to Rome roaming means keeping the same IP address now you can have intra controller roaming so you've just got one controller or you can have inter control around me which is a little bit more difficult but as you're walking through your say you're in a coffee shop and you've got ground floor here and say there's a concrete which normally is as a concrete floor and you go up the stairs look at my amazing stairs there and you're in the uh first floor I know you I think you don't have a ground floor in America maybe the first floor it's called the first floor but on the ground in the UK we call it ground floor and then first and so on what you don't want to have to do is reassociate with a new uh controller so basically you'd have to connect to um wireless network one and wireless network too you don't really want that you want to go in connect to their free wireless and then keep your IP address so 172.168.1.1 so keep it as you're roaming around the building if you're just using lightweight access points then you would have to just keep reassociating which in this day and age is obviously a pain because we're so lazy so I've mentioned intra controller and Inter controller you can see in the diagrams there the load balancer so this distributes incoming requests between two or more devices so your this is trans this will be transparent so what your clients think is happening is basically it thinks this is happening it doesn't realize that this device is here which is fine by us as Network Engineers will will take care of that and what it will do is balance so it will take uh the say the first connection here and then oh no this is getting really bad now it will log internally here and then this could be a network or just the device third connection here and it will balance and you don't have a single point of failure so your third connection goes here this load hits uh say 90 percent but this server it could be a higher powered server it doesn't have to be the same this is only sitting at twenty percent then it will route more of the traffic to here if this goes down for whatever reason transparent to all the end hosts it will load balance between these two and you can um you could be routing between different devices it doesn't have to be servers so you can balance web traffic streaming videos databases whatever you so wish now the IP address is actually sitting on here so say uh 12.1.1.1 and then these will have probably have non-routable addresses so RFC 1918 addresses which is whatever you know the the private IP address is but we won't care about that as customers moving on IDs and IPS uh Cisco Market leaders in this type of equipment uh I can't see what the model number is 4240. always great to serve the sales pages for all of these vendors uh Cisco and Juniper and whoever because it gives you lots of useful documentation you can see what's available now both of these do the same job they inspect traffic to detect unauthorized access and monitors the network for intrusions or malicious activities now what it can do is send an alert which is um oh no I'm gonna have to draw a this is actually a a telephone I hope you impress old-fashioned telephone there if you recognize that then you're officially old so you could send a message to your mobile phone it can send SMS log messages whatever you so wish or an SNMP trap and that will um it could shut down a port or whatever you instruct it to do now IPS Works in line so it's placed in the traffic flow so you've got internet and I'll stick it here actually your IPS and then that will go off to your router switch and then your your hosts here however many hosts you've got and I don't give up your day job so this is in line your traffic will come through here it'll be inspected and then go to your end device the IDS is not in line so what will happen is router switch host and it can be put here or here I'll say there's an ethernet connection here now your IDs receives a copy of the frame so the frame I'll call it frame um frame y and then that is just a copy because frame Y is actually being passed through to your switch obviously you can see the problem here is receiving a copy but this traffic is actually going through your network so these are less common now the RDS is I'm going to talk about these later in the security sections AAA or radius and used for authentication to validate the identity does a few things actually and um Josh talked about the different aspects of AAA earlier authorization determines what you can do and accounting is for the audit Trail so this um the accountant will normally go off to a server where you can interrogate the server logs and sometimes you need to do it for um compliance or um if you're going to legally take a case against somebody so it's a modular and scalable model for network and device access you can run it on its own server or certainly in the terms of Cisco you can have the server software running on your router and switch probably not recommended because routers are designed specifically to Route traffic uses radius attack ax plus and curb Ross as authentication methods don't I don't think airbrush is actually in the syllabus but I know a radius attack ax is certainly worth looking at the CompTIA Security Plus which we go into a lot more detail in this stuff I've already mentioned using the service uh UTM is an appliance integrates a range of security features but it does it into a single Appliance a while ago actually I was when I was Consulting in the early 2003 there was one company in particular brought out everything in a box bearing in mind the needs weren't as complicated back then so this box let's say boxer server we do your um email it would do your web it would get you out to the internet as well and then it would obviously connect off to your switch and I think it also had your firewall there's a few things it did but basically this was everything in a box that a small business would need so it does several things and it's designed to do them all pretty well your firewall your antivirus your IDs or IPS you can it has VPN software built in brands that you want to check out that are Market leaders at the moment are so fast which this is a copyright from their page and why jungle a lot easier for you to install and manage most of it will be running off the graphical user interface so rather than have to configure a Cisco device which is frankly quite a nightmare for most people unless you know what you're doing uh it just makes it a lot easier probably I'm I'm saying it's more suitable for the check the software because they may say different the small business the small to medium-sized Enterprise where you don't have a lot of employees and you may just have one support person or somebody that comes in just to do patches and maintenance obviously saves time and money so a big pull for any small businesses the only problem is if you're running everything off this I guess it's running off a server of some sort because it's software based then you've got a single point of failure so you've got to take this um into account with your business continuity planning what you're going to do if it part of it breaks all of it breaks Etc ngfw Next Generation firewalls so the hackers as you know are getting smarter and smarter and smarter and whereas and we'd have to be checking the IP headers or the TCP headers to find any malicious code it's actually now being buried inside the application data and traditionally your firewalls May well have been just checking these particular Fields headers Footers trailers whatever so I just got this image off um this URL here so these are known as third generation firewalls this combines your firewall with your other filtering looking at application and this is where the crypto lockers are hiding which we cover later and it can include antivirus ID management your transport layer security which is the latest version so secure sockets layer quality of service if you're running it on your network so if you're trying to prioritize Voice or video conferencing whatever you want to run at your work uh command firewall antivirus Gateway IDs IPS VPN software now eighty percent of the malware now targets your application so this is this is the software stuff and normally we wouldn't have been inspecting inside this part of the packet but this is where they're hiding it now and so you might things that have been downloaded off the websites or in hidden inside emails so this is why we need this third generation of firewall so blocking ports and filtering is no longer enough unfortunately so I mean just um Gathering more data spending more cash and having more stuff to support what this is known as here is deep packet inspection DPI so we're looking deep inside the IP pack here to see if there's anything nefarious in there the Deepak inspection you can see things that you wouldn't normally see looking at the headers and Footers and trailers worms viruses and it can also do so most importantly at wire speeds so the thing that we all hate in networks is latency I.E slowing stuff down it's really bad news for us and it obviously frustrates the users especially if you're doing voice and video conferencing it would be a nightmare they've added a voiceover voice over IP PBX into the syllabus and you can see we've got the voice Gateway router here I've got this from this website here easytalks.com so you've got your uh public switch telephone Network which Josh talked about which is your voice stuff and then we've got our traditional phones uh we've got our IP phones been managed here so we can all communicate within each other and then your voice PBX if you need to make calls to traditional landlines that can go out through the traditional public switch Network so IP private Branch exchange is a phone system and it but it also offers IP connectivity you get your traditional extensions connecting through your Lan and obviously you can go through the internet if you've got your traditional IP phone and you want to call somebody in the remote office with another IP phone and you can do that okay otherwise it would have to go through to the public switch telephone Network you can buy actually software so it'll run off a server if you so wish or you can have a hardware where you have to wire it up yourself mentioned it connects to the phone network and obviously use it if invoice is enabled on your network content filters uh what you can and can't uh Surf and I've got something similar on my home router although the Fairly rudimental level where I can block stuff that and the kids shouldn't be watching also referred to as information filtering depending on where you are usually software based and it's it's very simply blocks harmful websites or files such as Dot xees it would probably uh block um Facebook Instagram stuff you don't want people surfing while they're at work also you can work your local network so your um office here you could actually have it working for your core Network or you could let your ISP take care take care of it sometimes they're actually automatically block and certain content and certain websites especially in some countries where they they control politically what you can and can't say I think um Egypt and some other countries where they don't want you to see certain things which I won't go into that uh so your voice is enabled sorry that's uh but they're in error from another slide so multi-layer switch we've talked about your wireless controllers turning your access points into lightweight access points so they just forward traffic and your wireless LAN controller takes care of all of the routing security associations ssids that kind of stuff load balancer where it's sending your traffic transparently to two or more servers and obviously it's got your um the capability of if there's a one of your servers goes down it can balance between what uh or others are left RDS on IPS uh you've got to bear in mind what's in line and then what is out of line and just receives a copy because that's your typical exam question AAA server which I'll talk more about later uh UTM again probably small to medium-sized Enterprise but do check the marketing spiel Next Generation firewall which is deep packet inspections voice again if you're going out to the public switch telephone Network you'll need the voice Gateway contact content filter is blocking sites or content definitely dot XC files and um even even my online file that I share with my providers some of my Freelancers that work for me they can't reach this on them from their corporate Network either they're often blocked all right so that's all for now thank you very much for listening [Music] foreign network communications data transmission as you may know computers talk in bits ones and zeros ons and offs and this is how all of the data that we deal with in computers is transferred from one computer to the next or one node to the next over the media as we've discussed but we want to talk exactly about how these bits these ones and zeros get from point A to point B and so in this uh module we're going to talk about data transmission or how data makes it from one point to the other so we're going to start by talking about data transmission methods and defining exactly what data transmission is we're also going to talk about instantaneous data transfer and what might require it the word instantaneous meaning the data is sent instantaneously the minute that it is created in some instances data is first stored and then converted and then transferred in this case instantaneously the data is transferred over the media we're also going to discuss which we've seen in a plus serial data transmission meaning that one bit is sent at a time one after the other and remember just as uh you can recall one byte equals eight bits byte being represented by that uppercase b and a bit being represented by the lowercase b we're also going to talk about two different communication methods in serial data transmission asynchronous and synchronous Communications with which have to do with uh how the data is synced up to a clock cycle with the CPU and therefore how it's sent then we're gonna have to find parallel data transmission meaning that the data instead of being sent one after the other you may have eight bits of data all sent at Once In Parallel with the other finally we're going to discuss baseband transmission a digital transmission method and Broadband transmission or analog transmission method these are specifically called out in the network plus exam and so it's important that we pay a special attention to those now when we talk about data transmission it's important that we have to understand there are many ways that data can be sent and received in essence data transmission is the exchange of data between devices on network by one method or another the main thing that differentiates data transmission from say Voice or telephony transition is that we're transmitting many different things including text video and Graphics all over the medium whereas telephony is only dealing with voice this is different from our telephones which are are also transferring a sort of data but that data doesn't include as many different things now when you might hear the term computer network I just want to be clear that computer network is the same as a Data Network and so we might be using those terms interchangeably but when we're talking about data transmission sometimes the term computer network as opposed to Data Network comes up but they are interchangeable now in most cases when we're dealing with networking the data is stored somewhere at some point this also goes for data that's ready to be transmitted right we store it and then we send it however there are some instances when data needs to reach its destination as soon as it's been generated or created and we don't want to wait for it to be written to memory or written to a hard drive in these cases instantaneous as the name implies being instant to the moment data transfer occurs some programs and applications such as online chat uh video conferencing and voice conferencing programs all via the Internet require such a transfer the this method of data transfer doesn't store the data at any point before transmitting it to memory instead it immediately converts that data into a network compatible format and as it's being generated and then it instantaneously transmits it now you can understand why we would want to use that in these specific instances I don't want to store my chat stuff to memory and then send it I want to chat and then have it sent same with video conferencing or voice conferencing I don't want the lag that's going to occur due to having to save it to memory and then save it and then send it which is why we want this instantaneous data transfer serial data transmission is a transmission method that transmits bits once per clock cycle now this clock cycle refers to the CPU or central processing unit of the computer and how that's processing information and as you can see from this illustration basically what happens is we're sending one of these bits at a time and if you recall one byte equals eight serial bits and that's what we're going to call eight serial bits one byte now a couple examples of what's uh of what uses serial data transmission includes ethernet as well as some peripheral devices that connect to our computer like mice and keyboards now with serial data Transmissions there are different methods that can be used to delineate between the start bit and the stop bit basically how they know uh what where the data begins and ends and also error checking or correcting bits that allow the data to be uh fixed in case it arrives incorrectly and the data itself so let's take a look at the difference between synchronous and the asynchronous methods of data serial data transmission synchronous data transmission utilizes standardized time intervals when transmitting each bit now the assumption that is made is that one byte is sent every interval so the two devices have to be in sync with each other each other in regards to their timing a clock chip therefore not a great picture of it but imagine that this is a chip is needed to ensure that the devices are in sync with one another now a special bit pattern is inserted during a specified time interval to maintain this synchronization asynchronous on the other hand uses special start and stop patterns to differentiate between the bytes in the data Stream So the receiver just has to look for these special patterns and then can easily keep track of whether the data has been successfully received so for instance the pattern might be one zero one zero and then uh or one zero one zero one zero one zero and then the device knows that that is the beginning or the end of a pattern of bytes of data the benefit of course is we don't need this chip because the start and stop times are built automatically into the data itself now stepping away from serial data transmission parallel data transmission is a transmit Mission method that uses multiple transmission lines wires or cables simultaneously unlike serial transmission that sends start and stop and synchronization bits along with the data parallel does not and doesn't have to those bits are sent separately via one of these multiple other different transmission lines other than the data because of this throughput is generally better than standard serial transmission and these eight of these parallel bits are referred to as a character as opposed to a byte now some examples that use parallel transmission are scuzzy parallel ports PC card or pcmcia remember piece parallel ports those are those printer ports and may all use parallel data transmission it's not as used or widely used as a serial data transmission is now that deals with how the data is sent let's deal with the type of signal that's sent in baseband's transmission this utilizes digital signals sent via a direct current pulse and remember we're talking about direct current versus alternating current with base bands all the devices share the same medium or Channel and can't transmit and receive simultaneously however multiple baseband channels can be combined over one medium to use a channel separated with specific time slots and that's how we can determine when it's being sent and when it's being received one thing to notice in a digital signal as well is that we're only dealing with ones or zeros on and off and so the signal is either on or off there's no sort of wave that we're gonna get with the analog signal which we'll see right now so where baseband used those digital signals to transmit data broadband's going to use analog signals and you can see that represented in this wave also unlike baseband Broadband utilizes the entire bandwidth available and it's only going to travel in one direction or unidirectionally because devices can't send and receive over the same channel now if more throughput is needed that's fine we can combine and send across multiple frequencies channels or we can use over just one medium generally speaking we're going to see a lot of broadband in the field because a lot of our current infrastructure was created for analog signals as opposed to digital or baseband signals now Broadband over power lines or BPL is an emerging technology that still mostly in the testing phases in the US the premise of it is that we can essentially bring high-speed internet two power outlets using the power lines and the infrastructure that's already been built once this technology is fully developed you would be able to plug your computer into a power outlet in your home and you can get decently fast internet between 500 kilobits per second and three megabits per second which are about equivalent to DSL or cable speeds now of course the main concern with this type of transmission is a the effect that the uh since we're dealing with electrical interest infrastructure the effect that the electricity is going to cause uh on uh the data being sent remember we were talking about Emi and crosstalk and the noise issue previously and also security since if we're using something that everyone has access to we're also going to be opening our data up to some issues so for these reasons we might not ever see BPL or Broadband over power lines really come to full fruition especially with the prevalence of Wi-Fi technologies that are now becoming uh installed all over the place and might make BPL extinct before it even has a chance to flourish so just to cover what we've talked about we talked about data transmission uh meaning that we're transferring data over a computer or a Data Network we looked at instantaneous data transfer which means that the data is not stored to memory we also talked about serial data transmission in which one bit is sent at a time and remember we have eight bits in a byte we looked at asynchronous versus synchronous communication synchronous requires some sort of clock chip whereas asynchronous embeds start and stop into the transfer we also looked at parallel data transmission having bits sent all concurrently at the same time not as not as widely used and remember although I don't think you'll see this on the exam eight parallel bits equal one what we call a character we also looked at baseband transmission the important thing to remember there is that it is digital and Broadband transmission which is analog finally we talked about BPL or broadband over power lines which is a technology that would bring Broadband speeds over the power lines that are already in place [Music] thank you network communications media access methods so we've discussed and explained the different media and the different devices that exist on different types of networks and we even just talked about how that data is transferred from point A to point B but we have a lot of different devices of buying for access to this media in order to send its data and so we need to create certain rules that provide access to the media and so what we're going to talk about in this module is first what media access is and why we need it and why we need to understand it for the network plus exam and as administrators we're also going to describe two different barrage areas of media access including contention based media access versus controlled media access one in which we sort of fight for access to the media uh contend for it if you will and the other in which it is controlled generally by some sort of central device and then we're going to Define uh multiplexing which allows us to send multiple signals over a single medium and we're going to talk about two different types of multiplexing time division multiplexing and frequency division multiplexing and we'll discuss how those work and why we need two different ones then we're going to discuss polling which is how we check to see which devices need to send um data and we're going to differentiate between csma CD and CA now csma you don't really need to worry about that but it does stand for carrier sense multiple access but the real important thing here is to know the difference between Collision detection and collision avoidance and these are the two main methods we're going to see uh for ethernet and then for wireless and we'll explain why that is later on finally we need to differentiate between a contention contention domain and a broadcast domain basically uh how large or how many other devices they need to contend against or that can get broadcast a certain message and these are also divided by those two different devices that keep coming up switches and routers so if that seems confusing enough to you let's delve in in order to shed some light on what all of this is now as administrators it's really important that we understand the rules that are in place for different types of networks for instance if I were in a crowded room and I had a secret message that I needed to get across to someone in the corner of the room and I were just to shout out that message there's no rules in the world that say everyone else has to ignore what I'm saying and they could just listen or or there's nothing that says that everyone else couldn't talk at the same time meaning that then my message wouldn't make it now that's means there's no rules for communication in real life but in networks and computer networks and data networks there are many different types of rules and here we're going to talk about some of the media access rules or the rules that govern which node or which device has access and the ability to transmit on the media at any one time and when they're allowed to send and receive and for how long now these rules are crucial they ensure that data delivery and integrity and by the way when we say Integrity we mean that the data we intended to send is actually what was sent it hasn't been tampered with uh are maintained now there are two general categories for types of media access these are contention based and controlled media access so let's take a look at the differences between those now and they'll come back when we talk later about csma CD and CA not to mention contention broadcast domains with contention-based media access nodes on the network are competing with one another for media access time and utilization another term for this kind of media is competitive or Collision based and yes that means that they're actually the data packets are colliding and that's how we determine which can go right which is allowed to be sent now these are pretty easy to implement however data can be delayed for nodes that need immediate access to the network media because collisions are going to occur as the name implies and that's going to delay Network traffic now as a opposed to contention-based Media access we also have controlled media access so instead of me fighting for access to the media I'm granted access to the media and the way this works is we use a central device that's put in place to ensure that access to the media is guaranteed for devices that have certain time sensitive data and they can transmit it when necessary because of the because of this and these devices that need to be added these are much more difficult to implement and maintain but they're highly reliable as you can imagine and also make sure that no device has more access than another when it comes to access time so take for instance a device that has a safety function that when an emergency event occurs right it has to have immediate access to the network and to the network resources so it can send instructions to say heavy machinery that needs to shut down in case an emergency in that case we don't want it to be intending for Access we want it to be granted immediate access and so this is where controlled media access can really come in handy so while we're talking about controlled media access and we've just talked about controlled and contention based media access let's keep talking about control based media access more specifically discussing a few different controlled based uh or controlled media access methods the first I want to talk about is called multiplexing and multiplexing is a controlled media access method I'm just going to add control there so that we remember that this is related to controlled not contention based it takes multiple signals and combines them over one single Network medium now data can actually be multiplexed using two different methods time Division multiplexing and frequency division multiplexing so let's first look at time division multiplexing this is where channels are divided into time slots and each node on the network is assigned a specific time slot during that time slot the node has dedicated sole access to the network until that time has ended and then the next node is allowed to transmit now there's a device that we're going to talk about in just a minute called the Mox and this MOX takes the signals from each of the nodes and sends it across the network now with TDM multiple base band signals and remember baseband is digital again represented here by that Digital Signal because there is no curve in the wave which would be analog and we'll see that in just a second it allows these digital signals these baseband channels to be combined and sent over one network medium on the other hand we also have something called frequency division multiplexing this is where data from multiple nodes is sent over many different frequencies as opposed to given a specific time each node has complete access to its frequency and dedicated communication with the MOX that device that is basically controlling all of this the mux combines the received signals from the nodes and then transmitted across the medium the important thing you're here to know is that this we're dealing with Broadband or analog signals now we've been talking about uh the mux so let's just talk about that really briefly the MOX is the central device that or which is also called a multiplexer that combines the signals and transmits them to the receiving end or a demux or a d multiplexer separates the signals out again now remember this is all controlled access and this mux is that device we were talking about that is doing the controlling now a different type of controlled media access method is called polling and as the name implies we have a central device as well that goes to each node in the network in turn and C's and queries them do you have any data to transmit with polling then there is guaranteed access because the process is constantly repeating basically it's just constantly if we have this middle mux sort of device it's constantly going to each device and saying hey are you ready to send something you now have access although this guaranteed access in this method is reliable it might not be as effective in time sensitive Networks and time can affect sometimes potentially be wasted in this querying in this polling because sometimes I'm having to ask devices that don't need to transmit anything to if they need to transmit so this basically wastes time another example of this by the way is if for instance node a at one point finds it as data to transmit node a has to wait until basically the polling device comes all the way around to it before it's allowed to transmit the data now this can take a lot longer than simply just asking if it can then just send the data along now because of these negatives there's a variation of this polling which is called demand priority where each node signals when it has to transmit or not transmit this method contains within it measures to Grant priority to nodes that have immediate data that it needs to transmit it also contains measures and controls to ensure that nodes can't constantly signal they have priority data because then you would have one device that's constantly sort of hogging your network so those are our controlled based media access let's and and really we we see these employed in certain circumstances but you're going to more encounter contention-based media access and in contention-based media access there are two different types I want to talk about Collision detection is a contention-based media access method that attempts to provide Collision free data transfer in Ethernet local area Networks so the key here is this is what ethernet uses with csma CD or Collision detection nodes transmit when they have data to send and then when a collision occurs they're basically detected managed and then the data is resent or retransmitted appropriately to get a better sense of this and because it's one that we really need to understand let's take a look at um an image to give us an idea so there are five steps in Collision in this Collision detection which again I'm just going to throw this up there is a contention based media access method in step one we just say that the node itself wants to uh transmit data so what it then does in step two is it basically checks the network for availability now in step three the node transmits that data and waits for an acknowledgment from the receiver that it got there which is called an ack packet an acknowledgment packet in step four this is where stuff really happens uh if there is a collision the packet size will identify if one occurred because what happens is boom I have this collision and now my packet size changes so in step five if that Collision occurred both transmitting nodes and by the way the reason a a collision is going to occur is because another device is also trying to transmit at the same time so in step five if the Collision occurred I wait a set period of time and then I try to retransmit again now this might seem like it's not a very effective way of transmitting data but it happens at such a fast speed that actually it works quite well as long as we don't have too many devices in the same network contending for Access which we'll talk about in just a bit now you can understand why this works really well in Ethernet networks wired Networks because I can continue to collide and then send something out again and many times as I need until the data gets there but in wireless settings this isn't really going to work so well for us in this case we're going to use carrier sense multiple axis collision avoidance meaning we don't want a collision to occur in this contention-based media access method there are six steps that provide Collision free Communication in Wireless Lanes specifically now similar to csma CD nodes transmit when they have data to send however the node takes preventative measures basically by sending out a jamming signal or a signal to all the other computers that tell all the other computers that there is uh something to be sent and therefore no one else is going to send anything for a set period of time so let's take a look at this in a visual way so the first step in here like with the CD or like with CD as opposed to ca is that the transmitting node has data descend now the node checks the network for any Jam signals being transmitted by other nodes basically uh has another node already sort of said hey I need to send something if not the transmitting node sends uh its own Jam signal saying hey no one else send anything because I'm gonna send something right now then it waits a set period of time to allow all the other devices to receive this Jam signal and then it transmits the data now in Step six which is the last step the node monitors the network for any other Jam signals from other nodes and if a signal is detected it halts its transmission Waits a delay and then tries to transmit again this process as you can tell allows wireless devices to communicate efficiently in a contention-based network one in which it's contending for the right to send and receive data so this allows all nodes to have relatively equal access to the media now we need to have a an area in which all of these are going to contend for Access and in a contention domain nodes on the network are allowed to compete with each other for media access and then the collisions might occur as a result but this is why a contention domain is also considered a collision domain because this is where these collisions are going to occur now in a contention domain switches control the size of this domain and in larger networks we want to make sure to vot to divide these into smaller networks so that way we're not having to contend with as many devices at the same time so on the other hand a broadcast domain is simply a logical area of the network where all the nodes can communicate with all the other nodes without having to go through a centralized device because of this the device we're going to use is actually a router which is going to control the size of the contention domain in a broadcast domain now the broadcast domain refers to the set of devices that are going to receive broadcast data Transmissions from any node on that portion of the network which is also called a segment essentially if a node were to transmit a broadcast message the broadcast domain dictates where the message is going to go now in a contention domain if a broadcast message were to be transmitted there's going to be a greater number of collisions as a result of the traffic you can have multiple contention domains that make up broadcasts that make up a broadcast domain so I can have again divided by switches two different contention domains and multiple ones of these can make up a larger broadcast domain and because these switches are all connected by one Central router when one of the nodes branching off of one of the switches sends a broadcast message the router dictates that only the connected switch and its devices are going to receive that broadcast transmission so we first talked about defining media access basically the rules by which devices are allowed to communicate on the network we then looked at the two broad categories of access or media access that we deal with contention-based media access meaning we're basically fighting for the right to access the media or controlled media access in which we have a central device that decides for us we looked at then a couple different types of controlled media access these are all controlled media access types multiplexing which allows us to send multiple signals over one media and we looked at TDM or time division which divides It Up by time and remember this is for digital signals and then we looked at frequency division which allows us to use analog signals or Multiplex analog signals remember both of these use a device a controlling device called a Mox or a multiplexer and a d-mox or D multiplexer we also described polling in which we ask are there any devices on this network that want to send data but we talked about the fact that this can actually add more time to the process since I have to ask every device before I get back to the device that's ready to send we then looked at two contention based media access methods carrier sense multiple access Collision detection and collision avoidance and remember the important thing to know here is Collision detection simply has a collision occurs and then I just wait and I try sending again and this is what ethernet really is going to use as opposed to collision avoidance which is going to be used mostly in Wireless situations because I send out a jamming signal first we then looked at the difference in a contention-based domain or where we're contending for Access and remember that's defined by a switch because a switch uh everything connected to the switch can contend for Access and can have a collision and a broadcast domain which is created by the router and is simply a logical division of all the devices that uh one device can contact [Music] thank you network communications signaling methods we've talked about digital and analog signaling quite a bit but we haven't really gone into what that exactly means at a waveform level at a basic level and so in this module I want to cover some of the background information about these and outline some of the attributes that go along with them now this information might not specifically be on the exam but I think it's still good background information to understand anyway so uh in this module we're first going to Define what a signal is and what analog is we're then going to talk about the attributes of an analog signal well then take this and talk about a digital signal different from analog and a digital data transmission or how this digital Signa is transmitted we're also going to Define modulation and outline the Way digital signals are modulated and modulation really has to do with uh length or making sure that a signal can be broadcast or sent over a very long or large area or distance finally we'll look at Digital Signal reference methods how we know when the message begins and when it ends and finally wind up talking about Digital Data units or the unit of measurements that we hear often when we're referring to Digital Data such as kilobytes and megabytes so at its most basic level a signal is simply data or information that is translated into measurable transmittable and receivable formats meaning that it is what allows us to transmit and receive data now an analog signal is a signal that carries data in a continuous stream or a waveform via either electromagnetic or Optical energy and this energy can come from many different sources uh such as a electric current and the analog waveforms characteristics determine the information that it contains because the analog signal will oscillate between minimum and maximum values over time basically the analog signal has many attributes to it and it can be read in many different ways depending on the values and the information in the signals given now this analog signal as I just mentioned is many different possible values depending on the characteristics and how that signal is being read now the characteristics of an analog waveform can be described using the following terms these won't necessarily appear on the exam but they're good background information for you anyway first we have the crest or the peak of the signal this is the distance from the midpoint to the topmost part of the wave and when we talk about the midpoint we talk about this line that's sort of going through inversely the trough is the distance from the midpoint to the bottom most portion of the wave now the next term I want to talk about is amplitude amplitude is exactly one half the distance between the crest and the trough of the wave so it would either be this could be the what it's measured it could be the amplitude alternatively this could be the amplitude and the cycle is one complete oscillation of the wave from start to finish changing from one state to another and Back Again basically from the midpoint going up until we get to the next midpoint after it goes down now the wavelength is determined by the distance between two consecutive troughs or Peaks so here we're measuring the wavelength between two troughs we could also measure it between two peaks like so now the frequency also called the period of the wave is the number of complete cycles per second in a wave this is generally measured in hertz such as gigahertz or megahertz now the last term is the phase of the wave the phase is the relationship of the Cycles beginning to a fixed point in time meaning if two waves with the same frequency are transmitted at the same time they are said to be in phase and two that are purposely offset from each other or if they have different frequencies like these do they will be out of phase the device that plots the amplitude of an analog signal what would show you this wave is called an oscilloscope and you may have seen this perhaps at a store or even on TV and we can measure waves of all sorts of things for instance sound might be a wave that you've seen when you're running a program on your computer this gives you a real-time view of the analog waveforms and its shape if we've just as we've just described now unlike analog signals which can have many different values assigned to them Digital Data Transmissions utilize voltage differences represented either by ones and zeros these ones and zeros are what make up all of the information when there is a presence of a signal or voltage meaning that it is on it translates to one and a lack of voltage or an absence of this signal translates to zero now in computer networks digital waveforms can switch between two voltage levels depending on its relation to the ground if you recall what that is now because digital signals utilize voltage to represent its values of ones and zeros this is also called The Logical state of the data each bit or binary digit takes a predetermined period of time to transmit and bit patterns are used to establish the start and the stop of the sequence and the sink clocks which allows the receiver and the sender to be on basically the same page the sender and the receiver have to then synchronize these clocks to ensure proper reception or receipt of the data now there are a couple different ways that we encode in order to allow devices to tell which bit is what in other words to tell it when it starts and when it ends the first method I want to look at is called on off keying this looks at the voltage change from one state to the other within a pre-specified interval which is represented by the binary digit one and the lack of voltage or no voltage is represented by zero as we just saw now the synchronization between the sender and the receiver occurs with the receiver waiting for a series of ones because of this there is a potential for problems to arise especially when the sender has a long series of ones to transmit within the data this means that it could take a long while for the sender and the receiver to synchronize their clocks together in the event that the clocks are not sync then there's a high probability for data corruption as the receiver can't determine how many ones and zeros have to be transmitted now there are two variations of on and off keying I have listed here one is called the non-return to zero variation and the other is the non-return to zero inverted this type of data encoding scheme is typically used over serial ports and fairly slow connections I'm mentioning these because uh they're good to know but you won't have to worry about these for the exam now the next encoding scheme a little more popular perhaps is called Manchester encoding this scheme was developed in order to address some of the downfalls that we saw with on and off keying firstly Manchester encoding uses voltage differences to represent both binary digits so instead of just having one which is represented by a voltage and then zero which has no voltage both zero and one have voltages the way it does this is it works by assigning the voltage change from positive to ground or the binary digit 0 and a negative to positive change equals the binary digit one so positive to Ground Zero negative or ground to positive equals one this effectively eliminates the issue of too many one bits being transmitted and throwing off the synchronization as we saw with on and off King which relies on those one bits in order to sync up the clocks okay so modulation is the process of taking a weaker lower frequency analog signal that can't travel large distances and superimposing the signal over a stronger higher frequency called a carrier signal the carrier signal being constant takes on the attributes of the analog signal and it's shaped by either the phase amplitude or the frequency the resulting signal then has characteristics of both the original signal and the carrier signal that process this is called modulation and when receiving and when the receiving end decodes the signal by separating these two signals the carrier and the data the process is called demodulation so again we have demodulation which would basically take these away from one another and modulation which puts them together devices that perform this operation you've probably heard of before they're called modems and a modem is known for its ability to modulate and demodulate hence the name a modem is in effect a type of codec which is a software or Hardware that translates digital to analog formats and back this is an important thing to know for the exam a DAC is a digital to analog codec and in ADC as you guessed it is an analog to digital codec both of these exist in a modem now this is it in analog terms but digital modulation is also required which allows the digital signal to travel along distances and demodulation is the representation of Digital Data in an analog format for transmission over those longer distances so the analog signal has a characteristic changed to signify the difference between logical states of the digital signal this is a fairly simple as digital signals again only have two states one and zero and so the analog waveform needs only be changed or modulated in one way such as the graphic here the frequency is changed where the higher frequency represents one bits and the lower frequency represents zero bits in this way I can convert this Digital Signal into an analog one 1 in order to transfer transfer transmit it over a long distance now there are various methods to modulate the digital signal depending on what part of the analog waveform is being changed the first one is called ask or amplitude shift key modulation here only the amplitude of the wave is modulated and remember the amplitude is the distance between a peak or a trough in the midpoint and the result of this can only be one or zero the next method is called frequency shift key here the frequency is modulated to only represent one or zero as opposed to the amplitude and remember the frequency is the amount times we have this wave over a certain period of time we also have something called binary phase shift key in which case the phase of the wave is changed and remember the phase would be if I have 2 next to each other the difference between those and then I have quadrature phase shift keying here the phase is changed as well but we can actually have two logical States at a time for instance zero zero zero one one zero or one one this method actually allows for data uh to be more secure when it's transmitted so this is a more secure method finally there's something called quadrature amplitude modulation and in this case I can also have more than two states at a time but what I'm shifting here instead of the phase only is I'm also Shifting the amplitude and so these are both combined into one different modulating wave now in order to demodulate these once I've modulated them there must be a reference to differentiate the data from the rest of the signal now there are two digital signal reference methods that can be used the first reference method is called differential demodulation this takes the modulated and the demodulated signals and Compares them the output then becomes one mod one signal which is the data there's also something called a single-ended this method instead of using two different the modulated and the demodulated singles signals uses the ground as a reference point and the resultant information then becomes the data now again if this is a little confusing don't worry about it it's not going to come up on the exam I just want to cover this to give you a broad basis outline of what we're talking about here now while there is very good possibility that you've probably heard of some of these data units I'm about to mention at one time or another it's really important that you really understand them in their actual quantities now originally before computers became household items and now nearly ubiquitous computer Engineers came up with these measurements of data and it was pretty straightforward as we've mentioned before in computer systems and networking data is stored in binary digits or bits and a single bit is either a zero or a one this is the most basic form of measurement zero one being no power or power a lesser-known term but still cool nonetheless is that two bits together form a crumb bits contain a nibble and a bits together a byte that's how we got there bits crumbs nibbles bites now depending on the processor you have a word would either be 16 32 or 64 bits we generally don't see 16-bit processors anymore so generally speaking a word is either going to be 32 bits or 64 bits this doesn't mean a word that you've written on your word processor but a unit of measurement just like byte is now in most places Hilo is a thousand such as kilometers and uh in one thousand such as kilometers means one thousand meters while this is true in networking it becomes slightly more complicated because some sources Define a key a kilobit as 1024 bits While others might Define a kilobit as 1024 bytes one of the reasons for this confusion is and you can see right here how we get that 1024 2 to the 10th bytes and one of the confusion the reason for this confusion of bits versus bytes is because of the little B versus the Big B so here is a fairly easy breakdown that nearly anywhere you go and more importantly on the exam is going to allow you to have a perfect understanding of how much data we're actually talking about this chart specifies how the breakdown of binary data is mathematically calculated and this binary is a base 2 system and we'll talk more about that when we get into binary and creating binary um uh numbers like IP addresses and why is it base two because we only have two options a one and a zero which is a bit and remember eight bits go into a byte so this chart mainly demonstrates how that numbering system works the magic number I really want you to pay attention to is 10 24. that's the number of bytes in a kilobyte the number of kilobytes in a megabyte the number of megabytes in a gigabyte the number gigabytes in a terabyte so on and so forth now you're not going to be asked to calculate this necessarily but it's good to know nonetheless all right so we just talked about a signal and what analog means the signal being how that data is sent modified and received and then analog being that it can have many different values we looked at the attributes of a analog signal including amplitude Peak a trough frequency and so on we also looked at a digital signal and Digital Data Transmissions remembering that a digital signal can only have generally two values a one and a zero and depending on whether we're comparing it to each its own or to the ground we have different digital data transmission methods we also looked at modulating which allows us to send a signal over a more powerful carrier signal in order to allow it to travel long distances we looked at Digital Signal modulation techniques perhaps we got a little too involved in it and we talked about how then we can convert these Digital Signal into a analog signal for sending over data and then how we demodulate it back and we talked about the device doing this is called a modem which modulates and demodulates we also described Digital Signal referencing methods in other words how it knows where the signal begins and where it ends finally we described the Digital Data units specifically I wanted you to pay attention to the fact that one bit equals the fact that 8 Bits equal one byte and the fact that 10 1024 bits are in one kilobit or 1024 bytes are in one kilobyte [Music] Network protocols and services common Network ports and protocols all right now we start getting into what I think is the fun stuff in this network plus exam in some ways it's also where a blue bulk of the questions are going to come from by the end of this module you're going to be able to say what each of these numbers represents in terms of a protocol now if you took the a plus exam and I hope you did you probably recall some of these from there so this might be a bit of a recap for you but that's okay it never hurts to go over this stuff again especially because it just always pops up on the exam and as far as knowing stuff this is one of those things that you just have to know these these Protocols are what you really have to know we're going to talk about the protocols in more depth later too when we talk about what tcpip is but I want to start talking about these now since a port is really the end point logically of a connection so we're going to start by talking about what a port is in a little more detail and outline the different port ranges there are three of them well-known ports registered ports and then the last range which is um experimental sort of ports and private ports so we're going to outline the most common well-known default ports and the protocols that go along with them I'm actually going to give you a huge list of all the protocols you need to know and we're going to talk about some of those in depth in this module some in the next module and then some later on in the course but I'm going to get them all out onto a a chart for you right now finally I wanted to find and describe the common ports and protocols dealing with FTP or the file transfer protocol ntp or the network time protocol SMTP the simple mail transfer protocol POP3 or the post office protocol the uh used to receive email as opposed to SMTP which is used to send email IMAP which is also used for receiving or accessing email which stands for the internet message access protocol nntp or the network news transfer protocol uh something you may have used if you've ever used RSS feeds HTTP or the hypertext transfer protocol and https which is the secure version these are what allow you to browse on the internet and finally we'll talk about RDP or the remote desktop protocol which allows you to remote in to a Microsoft computer all right so let's talk about these in more depth first off we have to define a port in computers and networking a port is a process specific or application specific designation that serves as a communication endpoint in the computer's operating system meaning where the communication logically ends once it reaches the user the port identifies specific processes and applications and denotes the path that they take through the network now the internet assigned numbers Authority or the i a n a is the governing entity that regulates all of these Port assignments and also defines the numbers or the numbering convention that they're given now these ports range from 1 to over 65 000. Port 0 is reserved and it's never used so don't really worry about that now within this range we actually have three different subsets of ranges and as administrators knowing the common ports is crucial to managing a successful Network the common ports are some of the guaranteed few questions that I I know you're going to have on the network plus examination and nearly every other network examination as well so covering these and committing these to memory is of the utmost importance now within that range from 1 to over 65 000 there are three recognized blocks or subsets of ports the first block is considered the well-known ports these ports range from one to one thousand twenty three this is where we're mostly going to look at ports uh when we look at them in just a minute these are used by Common services and are pretty much known by just about everyone in the field now the next range of ports is called the registered ports range these span from 1024 to 49 151. these are reserved by applications and programs that register with the Iana an example might be for instance Skype which registers and utilizes Port I think 23399 as its default protocol don't worry about that but if you're curious for your firewall's sake this is the port I believe Skype uses finally we have the dynamic or the private Port range this is everything else 49 152 to 65 535. these are used by unregistered services in uh test settings and also for temporary connections you can't register these with the Ina they're just left open for anyone to use for whatever purposes you may need them so now let's talk about the well-known default ports you need to know for the exam this chart is really what you should commit to memory since uh and when you get to the test you want to be able to basically recreate this chart before you sit down and take the test you'll be able to do this in what's called a brain dump sheet so let's talk about the first portion of these ports we need to know the first is Port 7. this is for the icmp echo request or ping if you've ever pinged something from the command line this is what we're talking about we'll talk more about this a little bit later next we have Port 20 and 21. these are for the FTP or file transfer protocol which allows you to transfer files over a network we'll talk more about this in just a minute Port 22 is for the secure shell or SSH and Port 23 is for telnet both of those we're going to discuss later on in a different module but they're sort of allowing you to remote in and control a remote computer albeit not from a graphical standpoint Port 25 is the SMTP or simple mail transfer protocol which allows you to receive email and DNS or the domain name service which uses Port 53 is what allows you to transmit or to translate say google.com into its IP address when you're browsing out on the internet this is a really important protocol and we'll talk more about it later along with the the DNS sort of server Port 67 and 68 are for what are called DHCP and boot P or the bootstrap service for servers and client respectively one for uh servers and one for clients as we can see right here we're going to Define and describe those in more detail in the next lesson now Port 69 is the trivial file transfer protocol this is related to the file transfer protocol we mentioned up here but it is Trivial meaning that it is not a connection oriented and doesn't really guarantee that the file has been transferred Port 123 is the network time protocol which keeps the clock on a network or on computers on the network up to sync a great way to remember this is that time is always counting one two three uh Port 110 is for the pop three or the post office protocol which is how many of us download our email onto our local device and then Port 137 is the net bios naming service this is similar to DNS but is specific to Windows operating systems or Microsoft operating systems related to pop 3 is Port 143 which is IMAP the internet message access protocol this is another way of accessing and managing your email let's continue taking a look at a few more protocols that are equally important the first is the simple Network management protocol which allows you to manage devices on network Say by getting error messages from your printer or from a router this uses Port 161. we'll discuss this a lot more in detail later as well port 389 is the lightweight directory access protocol this is what allows a Windows server to have usernames and passwords Port 443 is https or the hypertext transfer protocol over secure socket layer notice the S here this is what allows us to browse the internet but securely we also have Port 500 which is ipsec this one also has another name which stands for Internet Security Association and Key Management protocol basically ipsec or IP security is what allows us to have secure connections over IP finally we're going into RDP or the remote desktop protocol which allows us to remotely access a computer Windows based specifically Port 119 or the network news transfer protocol which is not only used with Usenet a sort of Message Board that's been around for a very long time but also RSS feeds which you might be more familiar with and finally Port 80 is HTTP or hypertext transfer protocol the other thing to know about HTTP is it has an alternate Port of 8080 so you might see either one of these on there all right now I know that was a lot of information I just threw out there but we're going to cover these all in a little more depth as we go through here and I just wanted to lay them out in a very simple chart-based way so that you could commit them to Memory now let's talk about these in a little more depth understand how they function and why first up is the file transfer protocol or FTP this protocol enables the transfer of files between a user's computer and a remote host using the file transfer protocol or FTP you can view change search for upload or download files now where while this sounds really great as a way to access files remotely it has a few considerations that need to be kept in mind the first is that FTP by itself is very unsecure and an FTP Daemon which is a Unix term for a service has to be running on the remote computer in order for this to work you might also have to have an FTP utility or client on the client computer in order for you to have this protocol operate effectively and for you to be able to use it now trivial FTP is the simple version of FTP and does not support error correction and doesn't guarantee that a file is actually getting where it needs to it's typically not really used in many actual file transfer settings now just as I just mentioned you might need a client FTP uh software on your computer generally speaking there is a command line prompt that you can use it goes like this FTP space the fully qualified domain name for instance google.com FTP which I don't think is the actual one or the IP address of the remote host you only need one or the other if you provide the IP address you're sort of using the direct route if you're using What's called the fully qualified domain name which we'll talk about a little bit later then you allow something called DNS or the domain name service to do the translation into uh a IP address for you remember again that FTP uses ports 20 and 21 by default next is the simple mail transfer protocol or SMTP this is used to manage the formatting and sending of email messages specifically we're looking here at outgoing email using a method called store and forward SMTP can hold on to a message until the recipient comes online this is why it's used over unreliable wide area network links once the device comes online it hands the message off to the server the SMTP message has several things including a header that contains Source information as to where it's coming from and it also has destination information as to where it's going of course there's also content information which is inside of the packet the default port for SMTP is Port 25 although sometimes you might see it use port 587 which is uh by relay I wouldn't worry too much about that one for the exam but just keep in mind Port 25. now like SMTP POP3 is a protocol that's used in handling email messages and POP3 stands for the Post Office protocol version 3 which is the commonly used version now specifically POP3 is used for the receipt of email or incoming email and it does this by retrieving email messages from a mail server it's designed to pull the messages down and then once it does that the server deletes the message on the server Source by default although you can change that if an administrator wants to this makes POP3 not as desirable and weaker than most some other mail protocols specifically IMAP which we're going to see because it puts all of the brunt of the responsibility onto the client for storing and managing emails and deletes all the emails at the source so if something happens to your computer and you don't have a backup you're in big trouble the default port for POP3 as we mentioned is Port 110. so remember Port 110 is POP3 and Port 25 is SMTP now IMAP 4 usually just called IMAP is the internet message access protocol and it's similar to POP3 in that it's also utilized for incoming mail or mail retrieval but in nearly every way IMAP surpasses POP3 it's a much more powerful protocol because it offers more benefits like easier mailbox management more granular search capabilities and so on with IMAP users can search through messages by keywords and choose which messages they want to download they can also leave IMAP messages on the server and still work with them as though they're on the local computer so it seems that the two are synced together perfectly the server and the client also an email message with say a multimedia file can be partially downloaded to save bandwidth now the main benefit here is we're going to use this instead of first say a computer let's say I have a smartphone and a computer now it's going to make sure because the source is all stored at the server that if I delete something say on my computer that syncs up to the server and then the server will have that sync with this my smartphone so all of these are in perfect synchronization this is why it's much stronger than POP3 which simply downloads the email onto your client device by default IMAP uses Port 143 which is different from IMAP POP3 rather which uses 110. now ntp or the network time protocol is an Internet Protocol that synchronizes system Clocks by exchanging time signals between a client and a Master Clock server the computers are constantly running this in the background and this protocol will send requests to the server to obtain accurate time updates up to the millisecond this time is checked against the U.S Naval Observatory Master Clock or atomic clock so the timestamps on the received updates are verified with this Master Clock server which is again that US Naval server and the computers then update their time accordingly the port this uses is Port 123 which is as easy to remember as time keeps moving up one two three now if we add an additional n to the previous one we get What's called the network news transfer protocol this is very different from the network time protocol it's used for the retrieval and posting of news group messages or bulletin messages to the Usenet which is a worldwide bulletin board that's been around since the 1980s really since the internet was in its nascent stages the network news transfer protocol is also the protocol that RSS feeds are based on this stands for really simple syndication basically this is where a user can subscribe to an article web page blog or something similar that uses this protocol and when an update is made to that page or to that article the subscriber is updated so in this way you can get updated articles from your favorite web page just like you would new emails with nntp however only postings and articles that are new or updated are submitted and retrieved from the server slightly different from RSS but RSS is based on nntp the default port for this is port 119. so we're covering a lot of different numbers here it's really important perhaps even more than memorizing uh specifically what each protocol does that you definitely memorize which Port it's a part of if you can memorize by the way the number and what the acronym means you should be fine now a protocol you use every day even if you don't realize it is HTTP or the hypertext transfer protocol this is used to view unsecure web pages and allows users to connect to and communicate with web servers although HTTP is going to define the transmission and the format of messages and the actions taken by web servers when users interact with it HTTP is what we call a stateless protocol meaning that it may be difficult to get a lot of intelligent interactive responses to the information if you remember ever making very basic web pages using HTML or the hypertext markup language the language that HTTP is reading then you probably know this so if you want more interactive web page Pages or interaction with web pages then you're going to use different add-ons such as ActiveX that you might have heard of HTTP defaults Port is Port 80 and a common alternate port for it is Port 8080. now similar to http is https or hypertext transfer protocol over SSL which is the secure socket layer this is a secure version of HTTP so if you ever see an s on the end of just about any protocol you can bet that that has to do with this being secure and it creates secure connections between your browser and the web server it does this using SSL or the secure sockets layer we're going to discuss the secure sockets layer when we discuss encryption more detail in a future lesson now most web pages support https and it's recommended that you use it over HTTP almost every time you're able to the way you do this is simply by using instead of HTTP colon slash slash facebook.com just put an S in front yes Facebook supports this as do other social media sites and even email and even Google supports https why would you want to do this well say someone is browsing and or listening in to your Google searches that might be information you don't want someone else to know just as a recommendation absolutely anytime you visit any website but especially Financial uh institutions such as your bank or your credit union you want to ensure that in the bar it says https if it's not then opening anything in this including typing in your bank password could be really serious the same goes for anything when we're dealing with credit cards for instance buying something make sure that https appears in the bar or in your url bar at the top as we've mentioned before too the default Port is Port 443 now the last port I want to discuss is RDP or the remote desktop protocol RDP servers are built into the Microsoft operating system such as Windows by default and it provides users with a graphical user interface or a GUI to another computer over a network connection so this protocol allows users to remotely manage administer and access network resources from another physical location over the Internet which is represented by the cloud there are a few security concerns that come with um RDP and there is potential for certain sort of computer attacks so there are also non-microsoft variations available such as something called our desktop for Unix which if you are going to be doing a lot of remoting you might want to look into RDP by the way uses default Port 3389 although you can change that usually as well when we're using RDP we're also going to use it over what's called a VPN or virtual private Network which creates a tunnel through which your connection occurs this improves the security we were just talking about so let's review what we've just talked about first we talked about a port being The Logical endpoint of a connection and then we outlined the port ranges remember we had the well-known ports the registered ports and then the dynamic or private or experimental ports what we really want to uh learn for ourselves are the well-known ports I then outlined the most common well-known default ports and their protocols you want to memorize this table for the network plus exam I guarantee you doing that will get you a bunch of questions on the exam finally we Define to describe some of the specific ports and not only and we looked not only at the protocol and their protocols including FTP or the file transfer protocol ntp or the network time protocol SMTP or the simple mail transfer protocol POP3 or the post office protocol we also looked at IMAP the internet message access protocol and again all three of these have to do with email we also looked at an ntp which is not Network time protocol but the network news transfer protocol we looked at two different versions of HTTP one that is secure these allow for browsing and it stands for the hyper text transfer protocol which if you know HTML or the hypertext markup language then that might be familiar to you and finally looked at RDP or the remote desktop protocol I know this seems like a lot but I guarantee memorizing all of these and all of the numbers that they're associated with is gonna help you so much on the exam [Music] Network protocols and services interoperability services this word interoperability is a really long one but it's also a good one basically what this means is how different types of operating systems and computers can communicate with one another over a similar Network and that's what we're going to be discussing in this module so we're going to first cover what interoperability services are in a little more depth then we're going to Define some specific services that qualify as these particularly NFS or the network file system I'm sure you can imagine what that is from its name we're also going to look at SSH which is the secure shell and SCP secure copy protocol remember every time we see that s we want to think uh secure security that's a great tip that'll help you out on the test by the way secure copy protocols similar to SFTP or the secure file transfer protocol we're then going to look at telnet or the Telecommunications Network and SMB or the server messenger block which is what allows us to share for instance files and printers we're also going to look at ldap or lightweight directory access protocol and that word directory is important as it allows us to manage users in our Network mm zero conf in networking which also stands for zero configuration networking a set of protocols that allows us to sort of plug in and go without having to do a lot of advanced configuration and setup this is what allows us to have very easy Plug and Play network devices such as our Soho routers which is a good way to think about it however it's also deployed in much larger operations in order to ease the burden on administrators and technicians so in the previous module we discussed several different protocols that were used in the tcpip protocol suite and these allowed us to do a lot of different things by the way tcpip which is what basically allows us to communicate over the network in general is going to be discussed in more detail in depth later on in this course now because not all computers are made the same or by the same people or individuals certain protocols and services need to be in place to allow dissimilar systems such as PCS and Macs to be able to interact with one another so tcpip also contains these interoperability services that allow dissimilar services or systems to share resources and communicate efficiently and securely which is important if I want to make sure that no one is reading all of the information I'm sending between computers so these Services is what we're going to spend the rest of this module discussing now the first service is the network file system it's an application that allows users to remotely access resources and files a resource being for instance a printer and a file being like a Word document as though they were located on a local machine even though they're someplace else this service is used for systems that are typically not the same such as Unix which is the larger version or the commercial version of Linux and Microsoft systems now NFS functions independently of the operating system the computer system it's installed on and the network architecture this means that NFS is going to perform its functions regardless of where it's installed and since it's what we call an open standard it allows anyone to implement it it also listens on Port 2049 by default but I wouldn't worry about memorizing that for the test next SSH or the secure shell is one of the preferred session initiating programs that allows us to connect to a remote computer it creates a secure Connection by using strong authentication mechanisms and it lets users log on to remote computers with different systems independent of the type of system you're currently on with SSH the secure shell the entire connection is encrypted including the password and the login session it's all compatible with a lot of different systems including Linux Macs and PCs and so on now there are actually two different versions of secure show ssh1 and ssh2 these two versions are not compatible with one another which is important to know because they each encrypt different parts of the data packet and they employ different types of encryption methods which we'll talk about later however the most important thing to know is that SSH 2 is more secure than ssh1 and so in most cases we want to use that this is because it does not use server Keys ssh1 doesn't which are keys that are temporary and protect other aspects of the encryption process it's a bit complex and over the course of and over the objectives of this course however SSH 2 does contain another protocol called SFTP an SFTP or the secure file transfer protocol is a secure replacement for the unsecure version of plain old FTP and it still uses the same port as SSH which if you recall is port 22. so it's important to know that if we're going to be using SFTP remember FTP uses 20 and 21 if we're using SFTP we're using Port 22. now similar to SFTP is SCP or the secure copy protocol which is a secure method of copying files between remote devices just like FTP or SFTP it utilizes the same Portis SSH just like SFTP and it's compatible with a lot of different operating systems to implement SCP you can initiate it via a command line utility that uses either SCP or SFTP to perform some secure copying the important thing here to know for the network plus exam is not when you would use SCP over SFTP which is a little bit more complex but rather to realize that SCP is a secure method of copying as is as FTP that's how you're going to see this pop up on the exam now in contrast to all of this secure Communications I want to talk about telnet or the Telecommunications Network which is a terminal emulations protocol what this means is that it's only simulating a session on the machine it is being initiated on when you connect to a machine via a terminal by using telnet the machine is translating your keystrokes into instructions that the Remote device understands and it displays those instructions and the responses back to you in a graphical or command line manner telnet is an unsecure protocol which is why we don't use it as much as SSH anymore and this is important to keep in mind so when you send the password over telnet it's actually in what we call plain text whereas as we mentioned with SSH it transmits the password encrypted so if someone is reading the packets that are going back and forth they won't be able to hack your system if you're using SSH whereas with telnet they'd be able to read your password now telnet uses Port 23 by default which is important to know however you could configure it to use another Port as long as the remote machine is also configured to use that same port with telnet you can actually connect to any host that's running the telnet service or Daemon which again the word Daemon is a Unix version of service SMB or the server message block which by the way is also known as cifs or the common internet file system is a protocol that's mainly used to provide shared access to files peripheral devices like printers most most of the time and also access to serial ports and other communication between nodes on a network Windows systems used SMB primarily before the introduction of something called uh active directories which we'll talk more about a little bit later this is currently what's used in Microsoft networks now Windows services that correspond are called server services for the server component and workstation services for the client component now for example the primary functionality that SMB is typically most known for is when client computers want to access files systems or printers on a shared network or server this is when SMB is most often used Samba which you may have seen if you've ever dealt with a Mac or a Linux computer is free software that's a re-implementation of the SMB or cifs networking protocol for other systems even though SMB is primarily used or was primarily used with Microsoft systems there are still other products that use SMB for file sharing in different operating systems which is why it's important that we still familiarize ourselves with it ldap stands for the lightweight directory access protocol and this is what defines how a user can access files resources or share directory data and perform operations on a server in a tcpip network now this is not how they access it this simply defines how a user can access it meaning that we're really talking about here are users and permissions so basically ldap is the protocol that controls how users manage directory information such as data about users devices permissions searching and other tasks in most networks we're going to deal with this a little more in depth later on as well now it was designed to be used on the internet and it relies heavily on DNS the domain name service which we talked about is a way of converting say google.com into its IP address we're going to discuss DNS in Greater detail in another module now Microsoft's active directory service which we just mentioned and novell's NDS and e-directory services Novell being another networking operating system as well as Apple's open directory directory system all use ldap now the reason it's called like lightweight is because it was not as Network intensive as its predecessor which was simply the directory access Protocol no need to know that but I just wanted to explain the reasoning behind that light weight in there also it's important to know that port 389 is used by default for all the communication of the requests for information and objects finally zero conf or zero configuration networking is a set of standards that was established to allow users the ability to have network connectivity out of the box or Plug and Play or without the need for any sort of technical change or configuration zero con capable protocols will generally use Mac addresses or the physical addresses as they are unique to each device with a NIC or network interface card in order for devices to fit into a zero conf standard they have to fit or meet four qualifications or functions first the network address assignment must be automatic if you recall from a plus and this is something we'll talk about a bit later this is what we use when we're using DHCP second automatic multicast address assignment must be implemented which is also related to the DHCP standard third automatic translation between Network names and addresses must exist this is what we talk about when we deal with DNS finally discovery of Network Services or the location by the protocol and the name is required meaning that it must be able to find all of this information when it goes on the network automatically this is what allows users to be able to purchase a router from the local Best Buy or electronics store take it home plug it into their ISB or Internet service provider connection and automatically have it work automatically another implementation by the way of this is a configuration and networking called you PNP or Universal plug and play so to recap what we've talked about we talked about interoperability Services which allows for instance a PC and a Mac to communicate flawlessly over a network we then talked about the network file service SSH and SCP SSH being a secure shell working on Port 22 and SCP being the secure copy protocol similar to SFTP the secure file transfer protocol we looked at telnet which is sort of a plain text version of SSH so it's been replaced by it and SMB or the server message block allowing us to share files and resources between different types of systems finally we described and defined ldap or the lightweight directory access protocol which defines users and their ability to access all this stuff on the network and then we explained zero conf or zero configuration in networking which allows us to plug up a device and have it work almost instantaneously [Music] thank you welcome to module 5 lesson 1 ethernet standards pretty meaty subject this because it's got a whole bunch of standards and information as well as history to fit in what is ethernet the history why the name just in case you wanted to know I guess introduction of ethernet standards the Archer Police standard as well ATO 2.3 which you'll need to be familiar with which defines ethernet the IEEE as well what they do and their remit per view uh based on a Broadband some history really of the early days of ethernet networking which are depending on how old you are you may be familiar with some of the naming conventions uh the early days the early specifications thick nets in net and some of the standards here which we're going to run through which you'll need to be familiar with because you could be asked a question so that's a good reason as any uh ethernet it's the was or is the first high-speed land technology that in Connected computers high speed Laser Printers obviously in the early days there needed to be some agreed format for um Internet working devices to communicate actually invented by a guy called Bob Metcalfe back in 1973. it was remarkable in as much that at the time competing was dominated by some very large and expensive mainframe computers um to name IBM as a one of the main players at the time it's only a few people could actually afford to buy the mainframes and the information required in order to use them operate support and maintain was only known to a few people at the time so Bob actually changed the name of his first network from alto Alor Network to ethernet thankfully otherwise would all be referred to it as alto Aloha which um be a bit strange why the name he um Bob's experimental Network the physical medium or the cable to carry out all the bits to describe the important feature Bob named the network based on the word ether the old um luminous lumini Ferrera Ferris ether was once considered the medium for the propagation of electromagnetic waves so there are some mythical background in it and first standardized by the Consortium of deck Intel Xerox or Dix later actually standardized by the IEEE standards defined several aspects that make data transmission possible this is their job term ethernet is used to refer to both the original Dix ethernet which we'll rarely talk about unless we're doing and talking in the context of exams and the 802.3 specification which specifies ethernet old and new so 802.3 is an international standard for local area networks and metropolitan area networks that employs the carrier sensor multiple access with Collision detection the ethernet protocol frame format for communication the IEEE is the institute for electrical and electronic engineers uh largest Professional Association um for the advancement of Technology it has more than uh 400 000 members spanning 100 and more than 160 countries so what do they do they provide Society Publications they develop on new and emerging technology standards they also have conferences that various Network Engineers can attend to swap ideas and Advance the technology uh fortunately I'm not um this the points aren't sliding in as they should be so um all the information is appearing at the same time sorry so the ieee's leading developer of international standards they include the 802 standards which are for lands and mans and wireless local area networks also which will refer to usually as Wi-Fi you'll see the little stickers on Wi-Fi devices and when you go to cafes they may well have a Wi-Fi sticker to say them they give a wireless access and so ethernet's the most popular today it's everywhere basically making communication possible for pretty much everyone and mainly popular because of um the fact is economical to use it uses high speed it's reliable and it's easy to install and maintain also free to use the standards um like TCP if you used a custom Solution by another um Creator then you'd obviously have to pay to use all of their um specifications and standards so the early ethernet run over what was known as coaxial cables um modern ethernet don't do that anymore because of the limitations of speed and troubleshooting they use a mixture of copper and fiber depending on um the location and how much what the budgets of the various devices or um local government authorities have based on broadband is the term synonymous with ethernet the band is actually referred to the bandwidth in context of the transmission uh Broadband is a broadband system a whole band of transmission medium is shared dividing it into pieces called channels each channel will have the portion of the whole band multiple channels will serve as multiple signal carriers each carrying its own data on the same transmission medium so basically we're all sharing the same medium and the local ratio I think for my Broadband here is um 30 to 1 so 30 users will use one connection to the local um switch provided by the telephone company base band in the baseband system the entire band of the transmission medium will be used as a signal carrier naming conventions the ethernet standards username and Convention that houses determine a few things the speed of the transmission the signaling type and the length of the cable uh cable type used as well for example 10 base 5 really old standard this it was been phased out in the well late 90s I think when I was um just getting into networking really so 10 base 5 is named for the following 10 is the transmission speed which is 10 Meg base means the type of signal in his baseband and five indicates to the track the maximum length of the cable can be up to 500 meters this is for the segments you could have another segment after 500 meters and the signal would all have to be a replenished okay so a thousand Base TX the following is true a thousand indicates uh sorry 100 htx 100 is the speed which is 100 mag base stands for baseband again T indicates that the standard is twisted pair X at the end indicates that the K the cable is capable of full duplex communication 10 base 5 real old standard again um based on 802.3 the original standard uses a thick coaxial cable as its physical medium it was actually called thick net for short and you can see the picture of it there to actually connecting to the cable use these big plastic devices uh called um vampire Taps and they're physically screwed in to the cable and pierced it very awkward to use and hard to troubleshoot it ran at 10 Meg and either RGA or rg11 it had a little resistors on the end to stop the signal bouncing off the back of the cable and coming back and they ran at 50 ohm RG stands for radio government standard determ is a type of coaxial cables the distance was up to 500 meters there were a few pros and cons to using thick net you have protection against electromagnetic interference which can seriously degrade your signal disadvantage there was loads actually difficult to work with very difficult to troubleshoot cable was very thick so trying to expand it around an office without and people tripping over or hitting the head off them was quite awkward as well thin net is based on the 10 base 2 standard so 10 Meg um baseband and two stands for how long the and you could get the connection which is 200 meters was actually 185 was recommended but you couldn't you couldn't ensure to 185 so they called it 10 base 2. uh being cheaper than thick Navy was called cheaper net before we had any type of network and we used to use floppy disks big thick floppy disks not even the small ones that you might remember that was called sneakinet turnbass tea was one of the first modern standards introduced in 1990 it ran over 10 Meg over two pairs of twisted uh paired telephone wire and it allowed your network to use the existing telephone cabling which is pretty handy really easy to install reduce costs the cable could just be run off and you could cut it to whichever length you required and also obviously you could use a network switch which the uh thick and thin that couldn't use a switch or hub T denotes twisted pair wires 10 base T is category three cable we used to call it cat 3 for short in fact every category is is called a cat for um short High category cables can be used with the 10 base T ethernet so examples are CAT5 5e 6 6A and so on this changes every few months as a new category introduced High categories of the TP cables have higher specifications and they can handle higher data transmission speeds the term base T supports the maximum cable length of 100 meters 100 Base TX I mentioned earlier 100 Meg over two pairs of CAT5 twisted pair cable in you can get 100 meters before you have to terminate the cable we normally then go into a switch it's called Fast ethernet so 100 mag obviously 10 times faster than 10 base t uh became widely used because of its compatibility with 10 base T so imagine back in the day you would have your um the core of your network running at 100 Meg and then um unless if you didn't have the budget you would have your individual PCS connecting at 10 Meg into the network switch or hub they used a Cat5 cables a lot easier to upgrade because it used the same Cable in principles and same pin outs and determination 100 base FX f is usually designates fiber optic fiber standard for 100 Meg ethernet is 100 base FX so this is a 802.3 u specification it's 100 Meg ethernet over two multi-mode Optical fibers one's used for the transmission and ones used for the receiver as and designated in the diagram there the 100 base FX standard supports the maximum cable length of 400 meters in half duplex mode half duplex is pretty old-fashioned now to be honest or in full duplex mode which means you can send and receive at the same time then up to two kilometers half duplex mode as well just so basically it's like a walkie-talk here device can either send or receive data at a given time but it can't do both full duplexy can do both so it's like having a telephone conversation a thousand base T now we're talking 10 times faster than a hundred it's a IEEE 802.3 a b specification it's a thousand megabit per second ethernet Network uses four pairs of CAT5 cable or better and speak to your cabling provider to um find out what cable you can use minimum standards 100 meter length of cable it's um referred to as gigabit Ethernet 1000 bits that easy to install runs on CAT5 and inexpensive cables as an example of a CAT5 cable which I'm sure you've seen many times even if you've got a home computer so the Cat5 cables are four pairs of twist uh four pairs of Twisted wire which is eight individual strands the 10 and 100 base T only uses two pairs all four pairs are used by the EM thousand base t popular gigabit Ethernet and the Thousand base T is the most widely used version you've got the a223 standard that specifies other versions of gigabit Ethernet here are some of your options um thousand Bay CX LS LX SX uh you need to know some of this information but I think one of the questions they could ask is which one of them is um fiber optic and the answer is LX it's a question I've seen before I think I was actually asked in a Cisco exam not um uh CompTIA Network plus but good to know anyway so five kilometers to 550 meters depending if it's single or multi-mode and SX is implemented over multi-mode fiber as well so um LX and SX 1000 Base TX is gigabit over Cat6 cabling supports a maximum cable length of 100 meters uh uses only two pairs of wires for the data transmission now the Thousand Base TX you don't really see much anymore is a bit of a commercial failure mainly because of the Thousand base T the cost was so affordable you had to upgrade all of your cables from CAT5 or Cat5e to Cat6 which is a lot of inconvenience and expensive companies and downtime because of your all your core devices would need the connections would need to be um changed as well normally have to schedule downtime um for this 10 gigabyte 10g base t 10 times faster than a thousand base T ethernet operates at 10 gig and it's an 802.3 a n specification four pairs of Cat6 a cable or higher 100 meters maximum it's an augmented version of category six which you can see 6A isn't the same as six and frequency is at 500 megahertz next standard is 10gbase Sr this is gigabit Ethernet over Fiber Optic Cables I don't know why they don't just put a f in all of the fiber specifications it's a little bit annoying to be honest 802.3 specification is 10 gig ethernet over multi-mode fiber the SR stands for short range at the cable length is 300 meters so you only need to make a note of all of these in case they for some reason want you to um remember this generally most of us will just look speak to the sales advisor or just look on the um online or some documentation 10 gbase er 802.3 AE a gigabit over single mode fiber optic cabling ER stands for extended range you got up to full of 40 kilometers which is a quite a nice distance amazing distance in fact uh SW that was designed for use over a particular type of Technology sonnet or sdh again multi-mode fiber 300 meters again all right so we've covered a few of the basics of ethernet here the history the name the standards uh the oee what they do in brief I recommend you have a look in your own time at Wikipedia the popularity which is nearly always the fact it's the standards are free to use and it's affordable and everyone else is using the same standards baseband the Broadband the naming conventions and then some of the different standards here you'll need to know the different standards which uses a single and multi-mode how long um you can have a segment that lengths and that kind of thing all right so that's the end of the presentation thanks for watching [Music] Network infrastructure and Design Network models the OSI model so we're going to discuss two different models coming up here and the first model I want to talk about is the OSI model in this module now from this lesson you're going to have a thorough understanding of each of the layers in this module and there are seven of them and we're also going to talk about how those layers communicate some of the devices that operate at specific layers specifically layers one through three and some of the protocols that operate on some of these layers as well specifically the upper layers we're also going to have a better understanding of what the OSI model is and why we use a layered approach so this model is going to teach us everything we need to know about the OSI model we're going to begin by explaining exactly what the OSI model is and what the purpose of it is as well then we're going to go through and explain each layer from layer 1 the physical layer to layer 2 the data link layer later three the network layer layer 4 transport layer layer 5 the session layer layer 6 the presentation layer and finally layer 7 the application layer we're also going to discuss some of the protocols and devices that operate at each of these layers and we're also going to understand how communication begins and ends through these layers now early back in the 1980s late 70s when networking communication between devices which a lot simpler a lot of brilliant individuals from the iso organization we've seen previously or the International Organization for standardization came together and they came up with a a way to outline standardize and characterize the functions of a communication system or the methods by which computers are going to communicate in a network environment so they came up with this OSI model and I love it because I know the iso made the OSI and they did this in term of abstract layers so what we mean by these abstract layers and here they are again from the top down application press presentation session transport layer data link physical and just so we don't get confused the first layer is actually here at the bottom and the last layer is here at the top and that and viewing this we call this a top down approach as opposed to a bottom-up approach and these abstract layers outline the functions of the communications process but they hide exactly specifically how they're implemented in each layer in other words this really attempts to simplify and sometimes oversimplify exactly how everything in the network is communicated so let's say that we want to establish a highway more so we really want to build a brand new type of vehicle designed specifically to be driven on this very specific Highway and we're going to have to do it from the ground up so let's call this vehicle a bus not only do we want this bus to be able to run on any of the existing highways or they're out there but we also want the bus to be able to use the already existing bus stations as well so in order to do this we need to understand exactly what we already have meaning what the standards are already in place for a highway we also need to know everything about bus stations and everything about the infrastructure of the highway system that already exists regardless of whether we actually have to build the highway we still need to understand everything that relates to highways and their designs uh to the materials the limitations and so on so this way when we're designing our brand new bus we can ensure that it still can drive and operate on older highways not to mention new highways and that our bus is going to interact uh properly with the other buses and other vehicles that are on the road the other benefit here is if I'm designing this bus and I break it down into different layers seven of them I only have to worry about one part for instance there might be someone who is responsible for say the wheels and there might be someone else who's responsible for uh say the body and there might be someone else who's responsible for the highway and someone else who's responsible for the bus stop and so on and so forth this way I can fragment everything out and give everyone specific jobs and if a problem occurs with the bus then I can go to the specific person who with whom who is most familiar with that section or that layer this is the benefit to a layered approach to creating something so that being said let's talk about the very first layer layer one so layer one is the physical layer the this is the actual physical media the cables the wires this is the means by which the bits go from one point to another so for the actual cable uh the infrared connection the radio frequency even Wi-Fi all of these reference the layer or the pathway that the data is going to take so to take a look in this in the way that we were talking about it with our bus and our Highway setting if our main concern is building our buses we need to look at all of the other vehicles on the road we need to understand their size their shape other characteristics and so on so that way we understand how our bus can use the same tracks the other vehicles are using so here on layer one we have the path the road used for communication again this is the wire the Bluetooth fiber copper the Wi-Fi whatever means there is that physically the bits the ones and zeros rows are going over this media so the terminology for the information is considered simply the bits because we're actually transmitting the raw one and ones and zeros we're not dealing here with what the information is we're dealing with it at the most Electrical uh basic sort of standpoint so this is simply the mid the median this is called physical and as you can imagine this is also the very first place that data is going to enter into the computer right it goes over the chord and into a nick all right now what happens then well then we get to Layer Two which is called the data link layer an easy way to remember that the layer 2 is data link is because it's the only one that has two words it also has and this is not as important uh for this uh for the network plus exam but it's still good to know there are two what we call sub-layers the max sub layer and the LLC sub layer this layer in total and so these two make up this data link layer and this layer as a whole is responsible for allowing devices to share the same medium the medium being the physical layer so here we see a few things happening first we see a certain level of error correction and error detection on the physical layer we're going to see this a little more on later layers as well also and probably more important we see access control which I've denoted here and I'll get to this in a minute by the stop light so this function is performed by this Max sub layer again I wouldn't worry too much about that but the most important thing here is that we have physical addressing or the MAC address so anything that looks at Mac addressing and by the way Mac addressing is oddly enough performed by the LLC layer allows a device to look at a certain extra layer of information so whereas with layer one we saw physical if you remember we talked about hubs hubs just forward bits they don't look at the bits so they're going to operate at layer one here at Layer Two we start dealing with Mac addresses as a result this is where devices like switches are found and that's why switches are often called layer 2 devices there are more advanced types of switches but I want you to remember again a switch is a layer 2 device now if we look at this in a slightly different way here's where we have to be able to have access control on our highway so this is where we have to be able to have uh proper on-ramps that are only going to allow authorized vehicles to enter onto the road and we also need to establish standards for how the road is going to be used by everyone perhaps with signs and here we also remember this is where we establish how everyone is going to share the road who's going to access the road and a certain level of checking for damage on the highway and vehicles for instance people sort of going on and making sure there aren't potholes in this layer we refer to the data as frames of data because they're beginning to get framed we're no longer just dealing with the ones and zeros we're dealing with them in a frame or in a uh sort of larger context now the next layer is layer three or the network layer here's where a really a lot of exciting stuff happens okay first the third layer is different from the second layer in that the data link layer transfers data between devices that are within the same network okay so if you remember we talked with dealing with switches switches only deal with devices on the same network but here on layer three the network layer can allow us to transfer data to and from devices that are on different networks it does this by a specific kind of addressing specifically IP addressing and when we deal with IP addressing or the Internet Protocol we allow what's called routing so the main job of the network layer is really about this routing it's about routing and routers so knowing this and that IP addresses are used for routing we come to the conclusion that the kinds of devices we're really going to find in this layer are routers so routers are what we call layer 3 devices and that's you're going to see on the test now for the information to actually reach the destination this IP address has to be mapped to a physical address on layer 2. so the protocol that does this is called arp what ARP does is it Maps for better for a lack of a better way of describing it Maps Mac addresses to IP addresses by the way ARP stands for address resolution protocol this protocol actually operates slightly on the network layer and slightly on the data link layer because obviously it's dealing with Mac addresses and IP addresses now it's important that you consider that remember we talked about UDP versus TCP UDP being connection less and TCP being connection oriented that's when we're dealing with ports and we'll talk about that more we talked about that in a plus and we'll talk about that a little more later well everything in the network layer is connection less this means that it manages the transfer of data in a connection less uh mode it just sends the data but it's not going to wait for a reply to ensure it got to its destination this means we're sort of using a best effort here this is like dropping something in the mail and just hoping it gets there we're not using certified mail at all on layer 3 the information remember Layer Two we had frames well now we have something called datagrams so this is now we're moving up right we had frames now the frames are packaged into datagrams so if we keep with our method of talking about the bus metaphor okay from the third layer up we're going to concentrate on the bus itself so we've been talking about the road right we talked about the road itself the physical layer and then we talked about how people are going to share that road which is Layer Two data link layer now layer 3 the network layer this is the bus itself layer 3 through 7 concentrates on the processes that affect this container in our case the bus since we're basically designing our bus this layer is determining the best path that our data is going to take so in a manner of speaking this is like the bus driver on a specific route who's going to constantly updating us with routing information so it's saying here's our first destination here's our second destination here's our third destination just in case a route is blocked or if there's a faster or better route available layer 3 is where those Protocols are going to operate to find the shortest and most reliable path to our destination here on the fourth layer also called the transport layer some crucial functions are taking place now one of these functions is reliability it can be said that the TCP protocol what you might have heard in TCP IP if IP was on the layer 3 perhaps then layer four is TCP the TCP portion operates on this layer or at least close enough to the transport layer to be considered a layer 4 Protocol just to sort of secondary side note and we'll talk about TCP and IP a little bit more in depth in the next module they have their own model the OSI model is sort of a theoretical model it was never actually implemented as it was created that being said we still use it in discussing a lot of stuff which is why we need to talk about so the reliability is guaranteed by in here the connection oriented protocols that are on layer four so the transport layer has mechanisms that keep track of uh these segments and when segments fail the transport layer resends them there's also this acknowledgment feature such as a like a certified letter would have that ensures that when a message is received by the destination the transport layer is notified for instance by a message received successfully what we call a ack packet or acknowledgment packet besides these guaranteed delivery features we also have what's called data flow control this function ensures that during the data transfer the receiving end doesn't get flooded with too much data at any one time later in the lesson we're going to talk about different data flow techniques and flow control techniques that are used the transport layer is where something else called sequencing of data occurs basically when data is transmitted it's either broken apart or fragmented to be able to send it across the medium and when it's fragmented each fragment or piece is labeled with a specific number so that when the receiving end receives uh when the receiving end of the transport layer receives this data it can be reassembled and put back together in the proper order this is really important especially when data is received out of order as I just demonstrated now in essence this layer is much like the standards and the laws that we have in place on our highways they ensure that Vehicles get us to where we need to be safely and on time now some of the other protocols you may have heard of that operate on this layer are sctp uh some tunneling protocols and uh more importantly here when data is sort of partitioned out it's called a segment as opposed to a datagram or a frame now the next layer is uh I think it's one of the easier ones to memorize it's called the session layer and layer five and it's pretty simple because the sole purpose of this layer is to establish maintain when it comes time to shut down or conclude the communication session now while the OSI model assigns the responsibility of this termination of sessions to the session layer some other models have performed this on a different layer and we'll talk about that a little bit more some of the protocols you might see on here are for instance RPC which stands for remote procedure call and TLS and SSL as well so this layer manages how and for how long and what way a device is going to establish a connection during the communications process that the layer is not yet completed with its functions the rest of the network just has to wait so in keeping with the analogy of the boss in order to understand how the session layer fits in let's take a look at exactly why we're using our buses is it for transporting people or is it for transporting top secret documents from the main office building to the remote office this Y is going to determine several things for this layer right if it's determined that we need um several connections to take a private Highway for instance it might be determined that we need a private bus to take um special documents to maintain security or take a special Highway for instance so the session layer is what's responsible for determining what type of data and how we need to connect this session continuing on to the next layer is the presentation layer or layer six this layer is responsible for taking the data from the application layer which is the next layer we'll talk about and translating it into an intermediary language that the rest of the network can understand and it's also going to perform it in reverse on the receiving end also in this layer data encryption and compression takes place sometimes called the syntax layer because of its data encryption abilities as well as its conversion to a network relatable format or a format that applications can understand now what this really means is because the applications is going to have its own syntax or its own language the presentation layer is going to try to a map between those languages now if the mapping is available then the presentation layer is going to convert the data into Data units for the session protocol and after that it's send down the stack down the rest of the layers to do everything else it needs to do some of the protocols that operate this layer are anything that's dealing with compression for instance PNG jpegs Tiff a lot of these sort of picture file extension that you've seen this layer also performs code conversions they're going to take raw application data and compress them into more manageable forms for transmitting now regarding the translation capabilities of this layer think of like two different systems that are very different from each other one perhaps using TCP which we know another using ipx SPX which you don't worry about but it's another sort of protocol Suite this layer is what makes Communications available because of this we also know that a Gateway device if you recall from the devices we've talked about is a device that's going to operate on this layer because it's converting between two different types of Networks this is the biggest difference between a gateway and a router which as you recall operates on layer 3. a transceiver by the way and you remember a transceiver is that device that is on a Nick it's going to allow you to talk for instance between a copper and fiber Network also might work on this presentation layer depending on how we Define it other people might actually say it works on a physical layer now to put this layer in perspective the presentation layer is like having a double decker bus with a tour guide on a microphone who's translating everything that can be seen and heard to the passengers the tour guide is also going to help repack the tourists luggage for them which is like a compression and it's also going to add another level of security for VIP passengers who might come on board this is just like encryption here the formatting is simply making sure that the passengers are briefed and ready for their tour and making sure that they or the data is ready for the application so again we're really packaging this up for presentation to the application layer and the terminology for data at this point is going to be actually called Data so this is where we're moving up in the world we're no longer talking about segments or datagrams or frames we're here now talking about data it's packaged in a way that an application can read it finally at the topmost layer we have the application layer this is the layer that's closest to the user and it's the only one that the typical end user is going to be interacting with now even though it's called the application layer this doesn't mean that the application itself is on this layer but that the application layer provides utilities and services that an application could use for accessing network resources like some of these that we've talked about SMTP which allows you to get email DNS which is going to translate between an IP address and a fully qualified domain name FTP which is going to allow for file transferring ntp Network time protocol which is going to keep time up to date and HTTP which allows us to browse so for example let's say you have a file that you'd like to transfer to a remote computer right what method you're going to use FTP now the application layer provides the FTP services to the application you use which is some sort of FTP client the FTP client itself does not exist on the app application layer simply the protocol does this layer is the one you've probably dealt with the most and you're probably likely already familiar with without even realizing it for example you utilize this layer every time you check your email browse Etc and so on now some of these might not fit perfectly into the application layer and that's because again this is a theoretical model when we talk about the TCP model next it will see this working in a lot more of a practical way now because we all know we have many different applications on every one of our computers one of the purpose of the application layer is to regulate the communications between these applications and manage when they request services and resources so while it might seem easy to lump all applications together when talking about this layer the only applications that this layer is actually going to manage are those that have a Communications component so Solitaire would not qualify for this right but Internet Explorer which has all those browsing and protocols FTP DNS Etc is going to uh deal with this so this layer is also responsible for network access a certain level of error recovery and it's also capable of some data flow measures there's a lot of redundancy here as this is the seventh and the final layer this is where the information or process either starts or finishes so an application is going to create what it needs to be sent here and then unwrap the data once it's sent uh from one computer the next so to finish off our analogy of the bus um this is sort of like the bus station here's where all the people wait in line to get tickets to use the bus they're going to dictate the bus station is going to dictate who has access to the resources the resources being these buses and it's going to receive all the incoming drop-offs and process them as well as control the flow of people in and out of the station and it's going to notify people if there are problems on the highways and so on just as users are typically mostly going to interact with the application layer the bus riders are really only going to interact at the bus station layer right they're not going to be interacting with mechanics and building the bus or maintaining the bus or dispatching individuals or any of that stuff in most cases they're not even going to be interacting with the individual driving the bus so this is really where users are going to be doing most of their interacting now after going through each of of these layers we can now begin to have an understanding on how they're grouped together for instance layers 5 6 and 7 are what we call application support block when we look at each of these layers individually we can very easily see that the functions of each play a very specific role in the application management support and keeping them consistent the remaining four layers from the transport layer down to the physical layer are what we call the network support block these layers and the protocols and devices that operate on them are all Network related whether it's for routing or switching on the network or ensuring data delivery on the network and so on perhaps even making sure that the actual bits all the way down to those bits of data being communicated now as technicians and specifically for the exam you really want to know which layer relates to which support blocks and also this is going to help a great deal when we discuss the next networking model which is the tcpip layer model so uh just to sort of go through this again we start here at the application layer and we work our way down until we get down to the physical layer which is where the data can actually be transmitted over the network and then it builds its way back up until we get to the last application so if I'm browsing uh let's say this is me right and this is a web sort of server I send a request the request goes down all the way goes over the network it might even hit a couple routers along the way or switches rather so we're hitting some switches and then we hit some routers then we had some switches and then it's going to go all the way up again to the web server and then the web server is going to send that data back Etc and so we go this really follows on each end how data is being sent and received so before we wrap this up there's a couple ways to remember these and I'd really highly recommend committing this OSI model to memory there's two ways we do this one is called the top down approach this starts with layer seven and ends with layer one now the reason you want to just remember whichever mnemonic device I'm about to tell you just remember which one you're remembering so that way you know how to write it a great way to remember this one is all people seem to need delicious pizza uh now again all his application starts at seven so we're starting with the user and we're going down to physical to the hardware now the other way I like to remember this is uh please do not throw sausage pizza away that's my particular favorite now here we're taking a bottom up approach because we're going from the bottom up so realize that this you're starting with the physical layer and going up to the application layer so however which one of one of these you memorize you use to memorize this uh just remember to commit it to memory and when you get to your exam write it down immediately so you can just look at it and remember this is seven six five four three two one this is where hubs would function again uh they're just forwarding the same information just like this is where a cable would function data link is where most switches are going to function and on the network layer that's where we're going to see routers function this is the most information that I see on the exam and so if you Commit This to Memory I think you'll be set okay so just to recap one last time and review everything we've discussed first we explained the history and the purpose of the OSI model remember the important thing to realize here is that it's a layered model and the reason it's layered is to make it easier not only to develop things for each layer instead of having to develop something for the entire system I can just develop one little device such as a router or a switch and also it's going to be easier to troubleshoot and fix anything that goes wrong we then talked about layer one the physical layer right and this is uh where chords for instance the media exists and where all the bits are going to go from one place to the other we're really here dealing with the ones and zeros the electrical bits also remember hubs exist here as well we then talked about the data link layer this also had two sub-layers Mac and LLC and this is where we see Mac addressing or physical addresses start to occur and that means that here is where we're really going to deal with switches the data here by the way is called is put into what we call frames instead of just dealing with bits now the next layer is the network layer and this is where we start to see routing and this is thanks to a new addressing system specifically the one we're going to see the most is IP addressing this means here is where we're going to start seeing routers and don't forget here we see start seeing uh terminology for packets and the one we mentioned too was datagrams we also mentioned that this is where we see connection loss or connections that don't sort of have a definite got sent or delivery receipt we then looked at layer four which is where we see TCP from the IP Suite right and this is the one that's going to start looking at guaranteeing our delivery layer 4 is also where we ensure reliability and flow control here information is called segments when we get to layer 5 or the session layer we see that we're really establishing and maintaining a session this is where we're going to start and gracefully end our Communications such as SSL Communications when we get to layer 6 this is where encryption and compression occur this is also where we start seeing the term data finally we talked about the application layer or layer seven this is the layer that's closest to the user and this is where you're really going to see the interaction this is where we saw a lot of the stuff such as SMTP FTP HTTP and so on this really governs everything so if we go back through this with our metaphor remember the physical layer are the highways the date of the link layer or how we're going to share the roads remember we thought about a stop light the network layer is where we start determining the best route to get from one place to the other the transport layer tells us for instance the rules of the road the session layer is what type of Highway we might need to take for instance I might need to take a um a special private Highway if I have important documents the presentation layer is like the bus driver who is going to pack up our bags for us and also communicate and make sure that we know where we're going and the application layer is going to be like the bus stop now the OSI model is in actuality pretty obsolete but we need to understand the theory behind it before we can get into something that's a little more um uh necessary for instance the tcpip layer model [Music] Network infrastructure and Design Network models the TCP model whereas in the previous module we talked about the OSI model A mostly theoretical model that's in use in computer networks in this module we're going to talk about perhaps what is considered to be one of the most common or at least the most widely used model the TCP model now while it's important that we memorize and familiarize ourselves with the OSI model it's also really important that we understand this TCP model and the differences between it and the OSI model as technicians and administrators it's really important that we're familiar with each layer as well as how a data transfers between all of these layers and how all the protocols that are used in TCP relate to one another and in the layers so the objective of this module are first to explain the purpose and depth of the TCP model and to compare it in some ways with the OSI model we're also going to talk about what data encapsulation and fragmentation are these are really key to how large amounts of data are able to be transmitted and transferred over the Internet the largest Network in the world and then we're going to talk about the four layers of the tcpip model beginning with the fourth one and then the third the second and the first finally we're going to talk about protocol binding and something called an MTU black hole that doesn't really occur much anymore but that Network plus wants you to be familiar with so as mentioned before the tcpap model is perhaps the most widely known or used networking model it's uh another networking model that's most commonly defined using abstract layers just like we had with the OSI model and the entire purpose of this model is to allow for conceptualization of how a computer network functions in maintaining hardware and protocol interoperability also it's commonly called the dod model for the Department of Defense which funded much of the research that went into it uh TCP was permanently uh activated in 1983 and it's been in use just about ever since that wasn't until 1985 this model was actually commercially marketed but it is now the preferred network standard for protocols and so on now this means that using these four layers on this model the bottom being the network interface layer the internet layer the transport layer and then finally the application layer and if you know or remember the OSI model you'll see that there is some resemblance uh these understanding these this model and understanding how data flows is actually how the entire world is allowed to communicate and connect to the network so this is necessary for every computer in the world that is currently using the internet and for the most part that's on any network we might find other smaller lesser known protocols that do operate outside of this but I think you would be hard-pressed in today's day and age to see that so technicians and Engineers will probably sit and talk about Technology's implementation of these two models for hours on end and the reason is because there's quite a bit of history and Brilliant thinking that went into the creation of both of them the tcpap model was in fact created before the OSI model and it still makes it easier to represent how communication and network related Protocols are defined and relate to one another however it's still more common to hear technicians and administrators use the OSI model when they're troubleshooting or referencing networking devices and there are many similarities between the two models the first similarity is the obvious use of the layers to describe the functions of these communication systems although in tcpip we have four whereas in OSI as you recall we have seven some of them even have similar names as you can see uh from application and transport and then we see network or Internet and network interface which is very much like physical in some ways some people consider the TCP model to be a smaller version of The OSI model however this leads to some misconceptions about the position of relationships of certain protocols within the OSI model because these are very two very different designs and they have different purposes there are some recognizable similarities but they're still at their core different so the purpose of this OSI model was an attempt to simplify and standardize networking tcp's original purpose as opposed to the OSI is more attempting to sort of uh sort out the internet protocols into comprehensive groups according to their functions of the scope and the sort of network that's involved now one of the similarities between the two models is they both have interchangeable Network and transport layers also each layer of the OSI model directly correlates with the TCP model and here you can see the application layer the presentation layer and the session layer of the OSI model correspond to what we know as the application layer of the TCP stack this means that everything in the OSI model that fell into application presentation session are actually done in the application support block next the transport layer of the OSI model corresponds directly to the transport layer of the TCP model the network layer of OSI with the internet layer of tcpip and that is easy to remember since internet is really short for like internet working and the data link and physical layers of the OSI model correspond directly to the network interface layer of the TCP now some of these correlations it should be mentioned aren't precise and exact they're sort of approximations and that's because they are two very different models and therefore they were created differently and weren't necessarily created with the one or the other in mind that being said tcpip and OSI were built with knowledge of one another and so we do see this overlap now the TCP model outlines and defines the methods data is going to flow and commute in a communication system it does this by assigning each layer in the stack specific functions to perform on the data and ultimately each layer is completely independent of all the other layers and more or less is unaware of the other layers for instance the topmost layer of the application layer is going to perform its operations if the processes on the communicating systems are directly connected to each other by some sort of information pipe the operations that allow for the next layer the transport layer to transmit data between the host computers is actually found in the protocols of lower layers and from there on each data layer will complete its specified actions to the data and then encapsulate the data where it's then passed down the stack in the opposite direction when data is traveling back up the stack and we saw the same thing with OSI model the data is then de-encapsulated so when it's going down we call that being encapsulated and when it's going back up we call it D encapsulated so we really need to understand how all of this works together in order to get a really strong picture of uh uh TCP and be able to speak about the layers in general so let's talk about encapsulation each layer is responsible for only the specific data defined at that layer as we've said now these layers are going to receive the data package from the layer above it when sending and the layer below it when receiving this makes sense if I'm receiving data is going up so the data is coming from below and if I'm sending it's going down from the application down to the networking interface now when it receives this package each layer is going to add its own packaging which is called a header this header is used by the corresponding layer at the receiving side for specific purposes the exact purpose is really going to depend on the layer in question but this header is going to be added to the beginning of the data so that it is the first thing received by the receiving layer that way each layer on the receiving end can then remove that header perform its operations and then pass the remaining data up the stack up the TCP model on the lowest layer a footer is also going to be added and this is going to add to the frame by adding more supplemental information this extra data at the end of the data package is going to assist the receiving end on ensuring that the data was received completely and undamaged this footer is also what's called an FCS or a frame check sequence and as the name implies it is going to check to make sure the data was received correctly now on the receiving end this process is reversed by what's called de-encapsulation in other words the data is received at each layer and the headers are removed to allow the data to perform the related tasks where finally the data is received by the application uh the application layer and then the resulting data is delivered to whatever the requested application was now just like with the OSI model we'll talk about later this application layer doesn't mean the actual application itself it's simply the layer that provides access to the information from an application now just like the OSI model there are a few mnemonic devices that can be used to help in Remembering these layers in order and the one that I use the most going from the top down is called All Things in networking again that's application All Transport things internet in network interface networking so now we have a better understanding of how the data is going to proceed from layer to layer through encapsulation going down from application to transport to internet to network interface right and then through D inter de-encapsulation which goes the opposite way let's take a closer look at these layers starting with the topmost layer the application layer so here on the application layer much like the application layer of the OSI model we find what's considered the highest level protocols higher level meaning these protocols such as SMTP FTP and so on these Protocols are not necessarily concerned with the method by which the data arrives at it says destination but simply that it just arrives period here in the application layer we also provide the functions that relate to the presentation and the session layers of the OSI model as we've already pointed out it does this typically through the use of what are called libraries which are collections of Behavioral implementations that can be utilized and called upon by services that are unrelated so this means that the application layer of the TCP model encodes the data and performs any encryption and compression that's necessary as well as initiating and maintaining the connection or the session as we can see here these are just some of the protocols that we find at the application layer we can also further group some of these applications based on the specific type of function that they provide for instance if we're looking at protocols that are dedicated to transferring files such as FTP or tftp which of your call is the trivial FTP then there are also protocols that can be categorized by supporting services so some of those are going to be for instance DNS the domain name service and SNMP which is for management purposes or even boot P or the bootstrap protocol now just like the OSI models application layer this tcpip application layer is responsible for process to process level data communication this means that the application itself doesn't necessarily reside on this layer what more means is that it defines what the application or what type of application can be utilized depending on the protocol so for example SMTP specifies that outgoing mail communication with the mail or exchange server and IMAP specifies the incoming mail communication with the mail server also remember that only those applications that are network relatable are going to be managed this layer not necessarily all application so this layer's role is more towards software applications and protocols and their interaction with the user it's not as concerned with the formatting or transmitting the data across the media for that we have to move lower down into the model and get to the transport layer now on the transport layer of the tcpip model we have two main protocols that we need to be familiar with first we have the transmission control protocol or TCP and the second is the user datagram protocol or UDP let me just write those out here so that you can see what these stand for again now on this layer three things are going on uh data verification error checking and flow control now our two heavy hitting Protocols are done in very different ways so tcpap as we've talked about in the past is what we call connection oriented which means there's a guaranteed delivery whereas UDP is connection last which means it's just a best effort delivery UDP doesn't have any means of error checking that's one of tcp's areas of expertise so to put TCP and UDP in perspective I've always thought about it as if say a grade school teacher needs to send a note to a student's parent because the student hadn't turned in their homework for more than a week now the teacher can send the note one of two ways the first is through UDP or the uninterested doubtful pre-teen now this UDP is certainly going to make it home as quickly as possible but whether the message gets sent to the parent or not it really isn't udp's biggest concern getting there quickly is so UDP is going to have you that quick but not necessarily guaranteed now meanwhile the other method TCP or Teacher Calls parent this is the way the teacher has a guaranteed delivery of the message the parents aren't home the message cannot be delivered or something happens during the communication process TCP will wait and attempt to send the message again so whereas TCP UDP is quick TCP is guaranteed and so that's sort of the give and take there now while our story is a generalization it really touches on the two most important characteristics of these protocols now there are a few other uh specifics about TCP that are are really worth mentioning firstly and most importantly we have reliability like we just mentioned how it accomplishes this is TCP assigns a sequence numbers to each segment of data and the receiving end looks for these sequence numbers and sends what's called an ack or acknowledgment message which is something important that you do want to um be familiar with and you might also see that as a sin act which is the synchronization and that act message is sent when the data is successfully received now the sending transport layer doesn't receive the accurate acknowledgment message then it's going to re-transmit the Lost segment secondly we have data flow control which is we've already mentioned this is important in as networking devices are not always going to operate at the same speeds and without flow control slower devices might overrun by might be overrun with data causing Network downtime thirdly we have something called segmentation and segmentation occurs at this layer taking the tedious task away from the application layer of sectioning the data into pieces or segments these segments can then get sent to the next layer below to be prepared for transmittal across the media so the final consideration for TCP is in order for an application to be able to utilize this protocol a connection between port numbers has to be established the devices try to create this session using a combination of an IP address and a port number now this combination is called a socket in the future modules we're going to look at at referencing TCP and UDP as well as going a bit more further into explaining how they function and interact with different protocols but what you see here is the IP address on a specific port number so we know based on this port number what the connection is trying to attempt and whether or not it's TCP or UDP we know whether it's connection oriented or connection less the internet layer of the tcpip model corresponds directly to the network layer of the OSI model now the data terminology on this layer as I think we discussed when we talked about the OSI model is a datagram now as the internet layer relates directly to the network layer which if you recall was layer three we can a little more easily understand a few things that happen on this layer first it tells us that this layer is responsible for routing if you recall layer 3 devices for OSI are routers this means that it ensures the typically fastest and best path from the source to the destination this layer is also responsible for data addressing and if you recall with data addressing we're dealing with the second part of TCP IP which is the internet protocol aptly name send is since it is on the internet layer and the Internet Protocol is responsible for a couple main functions the first of those functions is what we call fragmentation it's important for us to understand something called mtus which are maximum transmission units so that we know why fragmentation has to occur now the MTU is the term as the name implies that's used to define the largest size of increment of data in bytes that can pass through the given Network device such as a router now often data is going to need to pass through networks with mtus that are less than the MTU listed on that device generally even uh not just match two but the lower it is the more it's preferred because then we can make sure that it's not going to have a problem so network devices are going to send and receive messages or responses to datagrams that are larger than the device's MTU in these instances when there is a datagram that's larger than the MTU of a device the transmitting internet layer fragments the data or the datagram and then tries to resend it in smaller and more easily manageable blocks so once the data is fragmented enough to pass through the remaining devices the receiving ends internet layer then pieces together those fragments during the reassembly process now in the header of those fragmented datagrams if we go back just a bit you'll see right here the header there is a specific field that's set aside for what we call three flag bits the first flag bit is reserved and should always be zero the second is the don't fragment or the DF bit now either this bit is off or zero which means fragment this datagram or on meaning don't fragment this datagram the third flag bit is the more fragments bit MF and when this is on it means that there are more fragments on the way and finally when the MF flag is off it means there are no more fragments to be sent as you can see right here and that there were never any fragments to send so as we see here our initial datagram that we wanted to transmit had an MTU that was too large to send it was 2500 and it was too large therefore to go through router B and so then we fragmented this datagram and added those bits to the headers of the fragments so that's how this all works and that's why fragmenting is so important now let's take a look at a networking problem that used to plague Network engineers and technicians that has to do with mtus for some time this is also something that's specifically called for on the network plus exam now a black hole router is the name given to a situation where a datagram is sent with an MTU that's greater than the MTU of the receiving device as we can see here now when the destination device is unable to receive the IP datagram it's supposed to send a specific icmp response that notifies the transmitting station that there's an MTU mismatch this can be due to a variety of reasons one of which could be as simple as a firewall that's blocking the icmp response and by the way when we talk about icmp we're really talking about the ping utility as well now in these cases this is called a black hole because of The Disappearance of datagrams basically as you can see I'm sending the data the data gets here the device the router here says wait a minute I can't fit that 2500 MTU through my 1500 sends a response but for some reason the response hits this firewall and doesn't make it back to the router and so the data is lost into this black hole now this is called a black hole because this datagram disappears as if it were sucked into a black hole now there are some ways to detect or find this MTU black hole and one of the best ways is to use the Ping utility and specify a syntax that sets the MTU of the icmp echo request meaning you tell it I want to Ping with this much of an MTU and so then we can see if the Ping's not coming back if it's coming back at one MTU and not another then we know oh this is what's happening right here and we can determine uh where the black hole is specifically occurring now on the bottom of the tcpip stack is the network interface layer now this layer is completely dedicated to the actual transfer of bits across the network medium the network interface layer of the tcpip model directly correlates to the physical and the data link layer of the OSI model now the data type we're going to be talking about on this layer are what we call frames as opposed to datagrams and the major functions that are performed on this layer on the data link of the OSI model are also occurring at this layer so we're really talking about switching operations that occur on Layer Two which again is that data link layer and so this is where we see switches operating which means that we're really dealing with Mac addresses okay now a MAC address again is a 48 bit hexadecimal universally unique identifier that's broken up into several parts first part of it is what we call the oui or the organizational unique identifier this basically says what company is uh sending out this device and then we have the second part which is the Nic specific and then we have the second part which is specific to that device itself so this is the manufacturer and this is for the device you can literally go online search for this part of the MAC address and it'll tell you what company is creating this device now the easiest way to find the MAC address in a Windows PC is by opening up the command prompt and using ipconfig all which we've talked about in a plus this brings up the Internet Protocol information the IP address and it also brings up the MAC address or the physical address that's assigned to your Nick so now that we've covered the MAC address is it's really important to understand the parts of an Ethernet frame and remember we're talking about frames at this juncture so the Preamble of an Ethernet frame is made up of seven bytes or 56 bits and this serves as synchronization and gives the receiving station a heads up to standby and look out for a signal that's coming the next part is what we call the start of frame delimiter the only purpose of this is to indicate the start of data the next two parts are the source and destination Mac addresses so the ethernet frame again this is everything that's going over this ethernet uh over the network we have the Preamble it says Hey pay attention now this that says now I'm giving you some data and then we have the destination and the source Mac addresses so that way we know where it's coming from who it's going to and this takes up 96 bits or 12 bytes because remember this is 48 bits right here so if we double that that's going to be 96 and then the next type is What's called the frame type this is two uh bytes that contain either the client protocol information or the number of bytes that are found in the data field which happen to be the next part of the frame which is the data this field is going to be a certain number of bytes and the amount of data is going to change with any given transmission the maximum amount of data allowed in this field is 1500 bytes we can't have more than that now if this field is any less than 46 bytes then we have to actually have something called a pad which is actually just going to be used to fill in the rest of the data and the final part of this ethernet frame is called the FCS or the frame check sequence and this is used for cyclic redundancy check which is also called CRC this basically allows us to make sure that there are no errors in the data now similar to the way that a an algorithm is going to be used to ensure Integrity of data the CRC uses a mathematical algorithm which sometimes we're going to refer to as hashing which we'll talk a lot more about when we get to Security Plus that's made before the data is sent and then it is checked when it gets there that way we can compare the two results bit for bit and if the two numbers don't match then we know the frame needs to be discarded we assume there's been a transmission error or that there was a data Collision of some sort and then we ask the data to be resent now this layer by the way this network interface layer is also responsible for the network access control and some of the protocols that operate on this are what are called uh point to point protocols ISDN which is a which we've talked about also a type of um Network and also DSL so these are some of the things that exist at this and this makes sense because again we're dealing with the physical bits bytes of data so now that we've taken a look at each of the layers in the TCP model there's still a couple things that we still need to Define now we've discussed how some of the protocols that we've seen relate to the OSI model as well as the tcpip model and we found that some of the protocols function much more smoothly when they're put into the context of an outline of one of these models so the next definition I want to make sure to cover is something called protocol binding this is when a network interface card receives an assigned protocol it's considered binding that protocol to that Nick so just we learned how the data is going to be passed down from one layer to the next it's very important that we have these protocols bound to the Nick we can have multiple protocols actually bound to one network interface card now of course the most easily recognized we can most easily recognize these when we're looking at the ipv4 and IPv6 configurations in our network connection Properties or adapter settings in Windows so for instance you use a specific protocol more than others and you're confident in the stability of the connection you can change the order of binding to potentially speed up your network since what it basically does is it's going to give a list of each protocol that exists and it's going to hit each protocol one after the other so if there's one that you use more you can set that at the top so it doesn't have as far to go so as we can see here we have several default protocols and they're going to be tested in order for that available connection and the first protocol that's found to have a matching active protocol on the receiving end is going to be the one we use now that while this might sound like a pretty decent method of doing things it also opens your computer up to utilizing a lesser protocol which is potentially going to give you a slower speed so the graphical interface or properties menu for your um network interface card is where you're going to be able to configure all of this stuff stuff such as tcpip DNS server assignment DHCP and so on and so forth so after all of this it's really important to understand that all this organizing categorizing defining of these protocols the assigning of rules and roles all of this the the internet didn't just happen overnight it's not even necessarily the way we did it on purpose these standards and these models are going to continue to expand and change and eventually might even have a brand new model that we're going to have to learn about but in the meantime these models are here to stay and they're going to remain really important and especially uh in the future you have to understand the historical roots of the network so you can be able to Define not only how to go forward in the future but also how to you know prepare yourself for a network plus exam so let's just go back over everything we've talked about one last time we covered in great a lot of stuff here right first we explain the purpose of the TCP model and we compared the tcpip model with the OSI model remembering that the top three layers if we look at this if we do the three two one and then we look at seven six five four right two and one physical and data link are going to go straight over here to uh that physical layer one of the tcpip model then the network layer is going to correspond directly to the internet layer the transport layers are going to be the same and session presentation and application all go over to the presentation layer in TCP we also talked about defining data encapsulation and we walk through how fragmentation works on the internet layer and the reason we need to do that is because of the maximum transmission unit finally we talked about the fourth third second and first layers of the tcpip model and on each model we outlined some of the important aspects of each layer such as the um application layer which again is the way that the application is going to process all this information the Tran sport layer which is in charge of reliability and it is where TCP which is connection oriented or UDP which is connection less live and this is also going to deal with flow control and also segmentation we looked at uh Layer Two as well which is the internet layer and the fragmentation that happens there and network one the network interface layer which is equivalent to all that physical stuff that we've talked about we also looked at how the terminology changes remember on layer four we're talking about data on layer three we're dealing with segments on Layer Two we're dealing with datagrams also called packets and we broke down then on layer one frames and an Ethernet frame and all the information that goes into that finally we Define what an MTU black hole was and we finished off everything by talking about protocol binding which is binding certain protocols to specific Nicks and in a in a delineated order [Music] Network infrastructure and design ethernet and implementing a wireless network so in the previous modules we were introduced to many networking standards models and Technologies now this module is going into ethernet a little bit further and specifically the implementation of a wireless network so the module objectives are first to outline the different types of ethernet networks that exist and then we're going to go into the explanation of WLAN or wireless LAN architecture then we're going to Define and describe the characteristics of an antenna and have different types of antennas which is actually pretty important for the network plus exam specifically wireless antenna performance factors and then by the end of the module we're going to have a complete understanding of the 802.11 standard and its Associated modes we're going to talk about uh the beacon frame and we're also going to talk about what determines where you place your wireless access point or your WAP and we'll finish by talking about how to properly Implement a wireless network so an Ethernet network is perhaps one of the easiest networks to plan and implement depending on the size of your network and the equipment being used there are a bunch of different kinds of small ethernet Network implementations that you can use some of the typical equipment that you're going to find in an Ethernet Network might be a hub an ethernet cable which can either be what we call straight through or crossover and we've looked at that a little bit more in depth previously and a switch or and a router so a network can also contain a combination of these or all of them generally so much we're not going to see hubs a lot anymore but they're still mentioned on the exam so a very simple ethernet Network that involves a hub is called a Hub Network Now to create this network all you need is two devices a hub and an ethernet cable this type of network is not capable of reaching the internet and it's typically only going to be used for file sharing or printing and you're not going to want to have a lot of devices either because it's quickly going to become very slow due to the fact that hubs as you remember operate on layer one of the OSI model and therefore broadcast every um uh input data out to everything else now the next type is also very easy to implement this is considered a crossover Network or a peer to peer Network and the reason is because there is no device sitting in the center a crossover Network only needs the two devices in the crossover cable to connect them and the reason we must use a crossover cable is because we're switching if you recall the one two three six pins we're switching these pins so that way on one side the data is sent on the other side it's received of course newer devices might not always need this crossover cable anymore because a lot of modern Nicks have Auto switching capabilities which will automatically determine and switch these pins for you now another ethernet network is one that uses a router to connect devices to the outside world or to the internet and a switch can often be placed in between the router which leads out to the Wan in the internal Network or the LAN in order to alleviate Network congestion and to allow for more devices to be added now just so we remember a switch operates on Layer Two although there are switches that do routing and those are called layer 3 switches and then the router as we just mentioned operates on layer three of the OSI model now another point about ethernet networks that is important is that ethernet uses destination and Source access points to assist in keeping tabs on all the multiple channels that are used in network communications these are called sap or service access points and in the previous modules we discussed how data flows through these layers in the network models well here these access points are used to map the network layer communication or IP through the physical layer or layer 1. now the access points allow a single physical connection to be utilized for many logical connections for tcpip this would be like a Nick because these access points are going to be on the local side only they're selected by the server managing those services now to keep what TCP as an example when a user is accessing a website for example a connection is made with the web server and the computer downloads that website along with the website are references to parts of the page such as files that are associated with the web page sound image other things like JavaScript and these files are stored on the web server and when the user interacts with the website the access point ensures that the computer can differentiate between the ethernet frames for the images and those for sound files and those for other types okay so in a lot of the previous lessons we've been talking about the methods of connecting our devices mostly through physical means and we defined that many Technologies are commonly used in both wired and wireless networks otherwise known as bounded and unbounded networks so here we're going to discuss specifically WLAN or Wireless local area networks in Greater detail starting with the architecture there are several components that we really need to Define the first component is what's called an sta or the station the wireless sta is any device that has a network adapter card or Nick that conforms to the 802.11 standard and you remember the specific standard for wireless is 802.11 as opposed to 8023 which is ethernet now the next device is called an AP or an access point look familiar now this is very different from the service access point I just talked about because an AP in this sense it is a device or a software implementation that allows wireless devices to communicate with each other and to connect to a wired Network an access pointer AP also sometimes called wireless access point offers wireless devices some higher levels of security as well and can act as the bridging component between the STA and the backbone of the network for access so the next component that we need to identify is the WDS or the wireless distribution system this device is the authority in terms of Access Control to resources and ensures that devices are mobile this allows multiple access points to be interconnected wirelessly which allows you which allows the aps to be connected and extend the wireless range of the network without having to connect the wire at the access points directly to the backbone and again the backbone would be the internet or the rest of the network if we're talking about a lan now the system has three types of AP stations we have something called a remote base station which is the access point that connects directly to the wireless clients or devices a relay based station just relays or repeats the information between other stations or devices and a main base station now the last thing I want to talk about is the main base station which is connected to the wired or Ethernet or backbone Network using these components there are a number of different ways we can actually configure a wireless LAN the service set is what defines how your network is configured now there are three standard ways that W lands or Wireless Lans can be configured first configuration is what's called a BSS or a basic service set the BSS in its simplest sense is comprised of an AP an access point and an sta a station although many stations with a single AP is also considered a BSS so I only need one station but I can have multiple the trick here is that I have only one AP now client nodes like these may not be necessarily explicitly aware of each other using a BSS we are easily able to extend our network coverage area and the distance between our wireless devices by forwarding packets through a wireless access point so that we can gain access to the wired Network now wlans can also be configured in what's called an ESS or an extended service set an ESS is comprised of two or more bss's basic service sets and the purpose of an ESS is to allow mobile devices to maintain a constant connection it's the network while you're roaming so each BSS in an ESS or an extended service set is going to have the same service set identifier otherwise known as an SSID this makes multiple bsses appear as if they're only one so as an example if you think about when you walk through an airport pretty much wherever you sit we have a decently strong Wireless signal theoretically of course so thinking about what's that signal they wouldn't be easy for a single access point to provide you a signal that's that strong for that much space in fact it's pretty much impossible so instead there are many access points APS arrange strategically to allow full coverage throughout the airport and combined they make up this ESS or extended service set that's why we see the same network name no matter where you are within that Network range now the BSS can either operate on the same channel or on separate channels which effectively increases the throughput by having separate channels that they're not going to overlap on finally we have What's called the ibss this is an independent basic service set and ibss is created when there is a isn't a controlling access point but instead there's what we call an ad hoc network and as the name implies this means that uh this is a makeshift or an improvised in technical terms uh wireless network that combines Network elements to make a network with minimal planning where all the devices on the network are essentially equal in status and are free to talk with any other ad hoc devices that are in range this ad hoc configuration which is also called by the way a peer-to-peer configuration is where stas are performing their own AP functions as well as their own client operations independent of any sort of central device so if you've ever connected two computers directly together in order to say transfer files or perhaps you've connected your smartphone directly to your computer in order to transfer files without the use of an access point you're using what's called an ibss or an ad hoc wireless network many aspects of antennas and their characteristics that are a little outside of the scope the network plus exam but there are still a few Basics that are important the first of which is to Define what an antenna actually is and how it functions on a fundamental level so an antenna is a physical device that are transmits or receives electromagnetic waves and then converts those waves to and from high frequency signal now the antenna's physical characteristics and dimensions are going to dictate these frequencies that it can transmit or receive and depending on the purpose of the antenna there are different types that can be used for instance the radiation pattern is different on some antennas versus others now another term we really need to understand is the term gain which describes the intensity of an antenna in a specific Direction related to the hypothetical intensity of a given standard which is the ideal in other words we always have a hypothetical versus the reality now this is achieved by focusing on What's called the RF or the radio frequency in a more manageable or concentrated plane this is what we see as strength on your computer right if you've seen this thing and you have different number of bars that's what we're really talking about here is the gain in most cases we want more gain which is better but there are certain legal limits and adding power can potentially have some negative ramifications so gain can also come from an external Source like an amplifier which means that it amplifies the signal making it stronger and it's measured in decibels now while this explanation is very simplified the antenna gain is how it's affected by things such as the size and shape of the antenna and the amount of electrical power that's applied to the signal and it's all kind of complicated which is why there are people who specifically are RF or radio frequency engineers so what you really need to remember about all this is first the physical characteristics of an antenna affect its gain second a higher gain is usually good but potentially dangerous third more gain can be achieved by using an amplifier and fourth we're going to measure it in decibels so now that we've defined some of this terminology when it comes to antennas let's take a look at some of the wireless antenna types now Wireless antennas can be fairly organized into two general broad categories the first category is directional directional antennas attempt to focus the radio waves into a narrow beam going in one specific Direction because the signal is being focused it typically means that these antennas are going to have a higher gain and for the same reason a relatively narrower transmission beam versus other types as you can see these characteristics allow for a couple of Bennetts benefits such as a focus beam which ensures a better signal quality and a smaller transmission beam which means that there's less area of interference how directional antennas are really commonplace in implementations of point-to-point networks which makes sense because I have this Limited sort of area in which the waves are going to be traveling and perhaps most commonly you've seen them in Dish Networks for satellite TV and the internet now the next category of antenna is are called omnidirectional antennas this type of antenna emits the radio waves in all directions on the same plane equally in some ways these are called donuts because the wave comes out in a donut looking shape now because the signal is being transmitted in any direction such as on a wireless router these antennas have a relatively low gain when compared with a uh directional antenna now where these antennas lack and gain they make up for it because obviously they have a greater coverage area as the donut wave implies the good part about this greater coverage area is that transmitting and receiving Stations don't have to have a specific alignment with one another they can be in any direction from the antenna these antennas are really going to be used in distributed networks and multi-point networks as well so omnidirectional antennas are implemented everywhere from cell phones to radio broadcasting antennas to walkie-talkies to GPS to mostly our wireless networks at home and in a lot of offices Etc so now that we've talked about a lot of the different types of antennas and their characteristics the the last thing I'd like to mention about gain is the more gain the antenna has the smaller the effective angle of use needs to be so the next thing we need to do is outline what's going to affect the performance of these antennas so the physical layer of the network the transmission of bits from one point to the other there are a lot of things that can hinder the data while it's in transit these things that are going to impede our signal are going to depend on the type of data in transmission so for infrared data Transmissions the antennas need a line of sight or Los just like your remote control almost anything that obstructs this loss is going to affect the signal this could include stuff like smoke smog fog dust even pulses of light and bright sunlight can very easily change the maximum transmitting distance and obviously if anything standing in the way we're going to be in big trouble now for microwave Transmissions the signals also considered Los or line of sight this typically doesn't mean that we need to be able to see the receiving station with our naked eye it just means that the signal has to have an unimpeded path from the source of the destination most commonly satellite the ground station has to be within the footprint of the orbiting satellite generally speaking distance is the performance Factor that's going to affect these microwave Transmissions the most now the factors that are going to affect radio Transmissions which are the ones we use in Wi-Fi settings mostly start with the antenna itself so the signal characteristics of an antenna can affect the maximum transmitting distance also performance can be limited if there are any objects that are very electrical or give off a lot of magnet magnetic fields near or around the transmitting or receiving stations and this is going to cause problems to arise we can also have normal ambient noise or environmental conditions which can affect the distance these signals can travel finally the greatest factor that's going to affect Bluetooth Transmissions is the distance between the uh the devices just because of the technology we're using as most Bluetooth devices are what we call Class 2 devices this means that we have about a 10 meter which is equivalent to around although a little more than 30 feet and this is due to power limitations now depending on the type of Bluetooth device it may operate on the 2.4 gigahertz frequency which by the way is the same as Wi-Fi and so there that's why we're going to have a problem and sometimes we're also going to see it on the 4.6 gigahertz frequency and for those that operate at 2.4 obviously not only does radio operate at those or Wi-Fi connections but also phones and so on so there's a lot of potential for having devices on the same frequency that are going to impede its communication now one other term I want to talk about is a term called latency this is we've mentioned it a couple times in previous modules but I haven't really defined it latency is basically the time delay in a given system depending on what system you're measuring it might mean slightly different things so the system we're most concerned with is the network latency which can be measured in either one way or round trip latency and I'm sure that you can understand the difference there the latency is the amount of time it takes for data to go from a source to destination and we're just dealing with bat round trip it coming back as well so the round trip adds the two one-way totals and doesn't include the processing time of the packet so only because it's sent and then takes a certain amount of time to come back doesn't mean that is all latency because some of that is how much time the computer is spending processing that information obviously we want lower latency and to measure it we can generally use the Ping utility which is going to tell us in milliseconds how long a packet took to go there and come back now let's look at some of the 802 11 standards and see which specifications have the least amount of latency so these 802 11 standards cover the proper implementation setup and performance minimums and device specifications for wireless local area networks these all fall under the 802.11 specifications they also specify the method for which those wireless networks as carrier sense multiple access with collision avoidance or csma CA which we've talked about are going to operate and it also designates the 2.4 gigahertz frequency as the band for the sped Spectrum devices that are going to utilize for reliability now over the years there have been several standards in this family that have been ratified the original was 802.11 just plain old it was named for its release in 1997 so the 1997 is part of that and it was specified to operate the 2.4 gigahertz frequency band and was rated for data bits at about 2 megabits per second which as you imagine would not be very useful for us now and therefore it is very obsolete at this point the 802 a standard which was released two years later was designed to operate at the 5 gigahertz band and it had a 54 megabit data rate now while it would seem that this standard would sort of lead the charge in Wireless standards at the same time that 802a was released there was also 802 B which was released and 802b operates at the 2.4 gigahertz band and essentially was a direct extension of the original 802.11 1997 standard now even though the data rate was faster with 802.11a there were some initial downsides to that standard that kept it from being the most popular first this higher frequency uh had a lesser range and so you could travel travel less distance also when 802.11b came out it was a lot cheaper than 802.11a and that made up quickly uh with consumers and so it quickly became the de facto standard now it's popularly grew rapidly and though it operated at 2.4 gigahertz and therefore was open to uh you know was really susceptible to a lot of interference uh it still was the one that almost everyone used uh and so that's sort of where it went because range was such a big deal the next standard which was released in 2003 was the 802 11g standard and this specification used the 2.4 gigahertz frequency again but the data rates took a major leap up to 54 megabits per second just like 802.11a now since it used the 2.4 band it made backwards compatible with 802.11b so it was very easy to integrate and it therefore became the preferred standard now after 80211g took over the market it wasn't until 2009 that we finally got the 802.11 N standard and it was released with something called a memo which was a type of antenna or multiple input multiple output and it had multiple antennas and that greatly improved the network performance also this amendment was specified for both 2.4 gigahertz and 5 gigahertz bands and so these improvements made the standard really popular especially because it was backwards compatible not only with G but also with b and even a and it was rated for a maximum of up to 150 megabits per second now the range of these Wireless standards is also specified the original 802 11 1997 and a have a range of about 20 meters B and G have a hundred meters and N is approximately 70 meters so we lost a little bit of distance because we added that five gigahertz band in but for most people this didn't really matter since we could use again an extended service set and simply add several 80211 devices now while you might have heard of some newer standards available and even some that are just coming around the corner these four are the ones you really need to know for the exam and so those are the ones I really want to concentrate on so if we look at these in a little more organized Manner and we can recap the important parts the 802.11 standard 1997 worked on a 9 a 2.4 frequency had a range of 20 meters and had a two megabit per second data rate Ada 211A was at 5 gigahertz 20 meters in range 54 megabits it's compatible with 802.11n 8211b operated at 2.4 gigahertz had a 100 meter range 11 megabits per second and is compatible with G and n ative to 11g also 2.4 gigahertz 100 meters and it was 54 megabits per second so it's increasing the top the speed and was compatible with the previous and the next one which is 802.11n which not only operates at 2.4 gigahertz but also five has a slightly less range but it does have a higher megabit per second data rate some would even claim that this goes up to 600 depending on your theoretical and it's compatible with all of the previous versions now there are two modes that are supported by the Ada 211 standard the first is what we call infrastructure mode this is the mode that's configured to use wireless access points to connect workstations to a cable backbone the network using the infrastructure mode is going to either use a basic service set or an extended service set the other one we have which we already mentioned is called ad hoc mode this is for those peer-to-peer configurations and again it's referred to as an independent basic service set or an ibss now the configuration of this mode is designed with each Wireless workstation able to communicate directly with one another without having to go through a central device now earlier in this module we talked about the service sets of many kinds and we talked about frames in previous modules now keeping those in mind it's important to understand how these devices such as laptops and smartphones know what wireless networks are available when we access them now this comes by detecting and receiving what are called Beacon frames a beacon frame is a management frame that's 50 bytes long and it contains information about the transmission process such as the SSID or the service set identifier which is essentially the name of your network the SSID is that text string that identifies the network it's 32 bytes long might be for instance Bill's Network or something like that now the beacon frame is used to start and maintain the wireless communication session and it's sent in regular intervals from the axis point and those intervals can be manually changed or set by an administrator and we can even turn them off so that way or hide them so that's not being broadcast now when it comes to installing a proper wireless network implementation we need to be familiar with the typical process and the steps to maintain the highest level of functionality now much like a lot of different processes the basic steps to take are pretty much the same they begin with planning so there are a few things that are helpful to collect before the planning process we need to collect information about the floor plan of the building where we want to install and so we can design a topology and figure out where to put access points we need to establish requirements for how many devices are going to connect which 802.11 standard we're going to use what type of security is going to be required and so on now all of these are crucial to proper planning without this information it's just going to be easy to choose the wrong devices or the wrong Technologies also if the research isn't done beforehand you're going to find yourself performing a lot of rework at the end now once this information is designed and gathered we can start to establish the type of access points and the number of APs needed knowing the number of users on the network is going to help us determine for instance how many access points and we want to balance the number of users with the access points in order to make sure that we have a good load balance the next step is to assess the building to see if anything around might cause interference specifically it's important to install anything that's going to be on the 2.4 gigahertz band now remember some of the things that can cause interference are Bluetooth devices other wireless networks heavy duty machinery and so on we also need to determine the exact placement of the access points are they going to be placed in the ceiling or somewhere visible or somewhere like a secure room and when we determine this we need to make sure that there's we're looking for obstacles that are going to impede like thick walls doors metal shelving uh proximity to large electrical equipment and if those obstacles Can't Be Moved we might want to choose a different location for our access point so now that we've planned the next part is the fun part the actual installation here we need to configure the device to connect it to the network and some of the standard things we're going to do are connect the router change the administrator default settings that the device came with and configure DHCP services and encryption levels such as whether we're going to use WPA or WEP and also are we going to use one of the three channels are we going to have them auto check or what another thing we might want to do is create what's called an access control list which means we can allow only specific computers to get access to our network via Mac addresses which are again the physical addresses on a computer or on a network card next we need to configure the client workstations and we need to test your functionality now it's important here because not all operating systems can use all the different standards they might even require a software update of some sort you might want to make sure to test the wireless device by walking around a building and make sure you can stay connected and that you can connect in the first place anywhere you need to and then you also need to take the device outside and make sure that no one can get in from the outside so it's actually quite difficult to just start one of these from scratch the last step in the process is to document every single step that was made and it's always a good idea to Baseline for future testing and implementations now being able to successfully accomplish the two phases the planning phase and the installation phase needs to be a part of your skill set needs to be something you understand for the network plus exam so just to recap everything we've talked about the first thing we did is we outlined the different types of ethernet networks whether that means it's a Hub Network a router Network or a peer-to-peer Network we also explained WLAN architecture looking at the difference between a basic service set an extended service set and an independent basic service set we defined and describe the characteristics of antennas looking at gain and the types of impedances that could occur then we outline the Ada to 11 standard including a b g and N which are the different modes we also talked about which frequencies these live on whether 2.4 or 5 and how fast are the megabits per second that each one provides you want to make sure to commit to memory that table that we displayed on an earlier frame we also talked about defining Beacon frames which broadcast the SSID and tell computers how to connect to the wireless network finally we outlined what factors are going to result in where you place your access point and how to properly Implement a wireless network point from the planning and implementation stages [Music] welcome to module 5 lesson five IEEE 802.11 AC actually we're going to look at a little bit more than that the N standard 82.11n AC Channel bonding now the 802.11 it's a specification for wireless LAN WLAN communication it uses mimo which we shorten from a multiple input multiple outputs I'm sure you can see why so in this technology the transmitter and receiver use multiple antennas I've put a little diagram on the bottom here from um ieb media that it will demonstrate at the bottom certainly you can see three channels in use simultaneously multiple channels on the top part of the Fig you can see you can select from but it's only using one so in this standard the end standard multiple antennas provide independent paths in space between the transmitter and the receiver to send or receive streams of information at the same time on the same band what my mode does is increase the number of data streams sent from an access point to a client which you can see in the bottom part in 802.11 mimo four spatial streams can be sent to a single client at a time again if you want to read further you can now look up the specifications there's a few Wireless specialty books if it's something you're interested in doing it's certainly an interesting field uh the 802.11 AC is an enhancement of um 11n obviously still Wireless networking it's designed for high throughput our wireless Lans on the five gigahertz band there's a few advantages to using that it uses a multi-user form of Mimo in their mind mode the access points has multiple streams of data at the same time to different clients over the same frequency spectrum in uh 802.11 acmu mimo eight special streams can be divided among up to four clients I think the MU is multiple user yeah multi-user mimo at the bottom and you can see the stream can be broken up you've got a few options you can have a higher stream to one client and then lower bandwidth stream to another clients supports treatment of HD videos which is really handy and to multiple clients because of low latency high throughput and reliability it operates in the five gigahertz band I already mentioned that theoretical data rate of 600 this has been improved on all the time so maybe check up on the um standard before exam day you've got less interference than in the 2.4 gigahertz band which is where you get the increased performance more channels available for data transmission greater number of non-overlapping channels than you do in 2.4 megahertz I think there's a couple of disadvantages as well but I'm not sure I'll put them down here in the slide so the U.S a five gigahertz band has 25 non-overlapping channels whereas 2.4 gigahertz is only three uh Channel bandwidth of the following 80 160 20 it's worth and making a note of all of these in case it's asked in the exam and 40. uh obviously needs to comply with the standard you can see this particular adapter's got it written on it it's got a AC standard written on it to comply with the standard as to support the 2040 80 megahertz Channel bandwidth in the 5 gigahertz band the 160 megahertz Channel bandwidth is optional 80 megahertz channels are formed by combining combining the following following two adjacent none overlapping 40 megahertz 160 megahertz are uh combined to 80 megahertz I think you can see how this works so here I've put um a slide from Wi-Fi Jetty website they've combined two channels here to 20 megahertz channels are made of 40 for channel bonding so Channel bonding was first introduced with 802.11n in Channel bonding two or more channels adjacent to each other are combined to increase bandwidth as you can see in the figure put there benefits 802.11 AC benefits because it supports the following channels 2040 80 megahertz uh although 160 megahertz channels are supported as an option is its availability depends on your geography Where You Are well I just had a bandwidth increases the data rates so um 11ac uses eight spatial streams and 160 megahertz bandwidth to achieve a maximum data rate of 6.933 gig uh data rates vary on the following for 11ac you're given bandwidth and the number of spatial streams used probably worth um writing out this um table here if you want the information or you can do a screen capture 802.11 AC with one spatial stream and for a bandwidth of 20 megahertz can ensure either data rate of 86.7 megahertz and so on and so forth for the others um their data rate increases both vertically and horizontally all right so we've covered NAC Channel bonding that's all for now thanks for listening [Music] plug the module 5 lesson 6 in network segmentation quite a bit to cover and some of this is a little bit esoteric to be honest so um it's conceptual it can be a bit hard to get your head around um in that sense what is Network segmentation what is physical segmentation logical uh the uses why bother and critical situations so we're hitting a few the syllabus topics here in the um Network plus syllabus so in a sense Network segmentation concerns dividing a computer into Network or sub networks not in the sense of um subnetting um in the context of Ip addressing but um dividing our network down so each portion of the network is called a network segment it can be characterized by a physical boundary or logical So Physical something you can see logical something that the network can see but you couldn't see physically you would then have to log in and check the configurations so physical or logical boundary separates various Network segments from one another physical is a bit easier the computer is divided into segments for example with switches routers a group of physical access and assets is part of a specific Network segment so a bit harder to do with switches because you would normally needed to add a configuration because switches are designed to broadcast to other um parts of the network if it doesn't know where that part of the network is or particularly device whereas routers do the opposite computer network is logically um virtually divided into Network segment so this is uh from The Logical standpoint so we could do it with virtual lands or vlans virtual segmentation is done or different connections or the same physical switch so you can have 10 switch ports and the first five ports are in one logical part of the network in one VLAN VLAN 10 for example and the other five in VLAN 20. and you could have multiple vlans depending on your capabilities or whatever switch you're using through through Network segments are isolated although secure communication can be established between them to share network resources we cover that with security and elsewhere you can actually have an internal and external network security it isn't just for example vpns connecting and through from remote offices so why would you bother in a sense it enhances the security of the network you can isolate critical parts of your infrastructure from an authorized access for example if you've got a special service and server you can restrict access to the um users don't access it and they don't have direct access so they'll be in a different VLAN for example or just in it wouldn't appear on the network and you normally or may well have depending on the size of your network a different team or Department managing that part of the network it can be used for reducing Network congestion so you're dedicating certain parts of bandwidth for certain segments of the network and you can even have a high-speed department for example um the company I used to work at we had a design team who all used um high speed high resolution files and graphics and it um they needed um a fast connection so they had their own logical segment and you could also limit traffic as I said faster connection for some slower for others and the available bandwidth is um increased or reduced accordingly uh also useful for load balancing you can distribute the traffic a load based on the for the network certain devices certain devices can be placed in certain segments and network segmentation is also done for the PCI the payment card industry that's different from the PCI bus technology which we discuss elsewhere the PCA compliance standards were created by Major card issuers and you may come across it if you have to take online payments um depending on the processor you use even if you've got a small um Network for your business or shop you um may have to or you will be affected by PCR compliance so this is to ensure that the payment transactions are done in a secure environment if someone processes stores or transmits credit card information it must comply with the PCI Data security standard which is the DSs this is mandated by Visa Mastercard American Express discovering JCB obviously because people will try and capture and credit card information so it needs to comply with the standards um Network segmentation is actually not a PCI DSS requirement it's done to isolate the traffic that stores processes or channels emits the card holder information from the rest of the network and reduces the scope of the network environment subject to PCI compliance if you didn't have your network segmented then your entire network would have to comply with all of the various pcid SS requirements if you segment the card processing and part of your network then only that part of the network needs to comply so it's going to make your life a lot easier um uses the footprints of a sensitive information is confined and this is what I I mentioned a moment ago and you can protect it using firewall or your intrusion detection or Protection Systems and reduces the audit cost as well the audit is done for specific Network segment as opposed to your entire network and again the best example is when you're getting audited for the purposes of of PCI compliance and this is one of the uh topics for these syllabus actually Network segment segmentations in critical situations numerous situations where the network segmentation is critical so the scada the supervisory control and data acquisition and the ICS industrial Control Systems so again you'll see you'll see this on the syllabus when you look the ICS refers to several control systems that are used in the industry in various Industries this is an industrial control system so you may not have heard of this or may never come to deal or support or manage this unless you're part of the industrial Network infrastructure thank you and the additional facilities are electrical electrical power grids water distribution oil natural gas pipeline systems and they're dependent on electrical hydraulic and mechanical equipment this equipment is all monitored by sensors that transform the physical stimulus for example something's broken or stuck or doing too much or too little of what it should be doing and this is um changed into electrical signal and in a basic SC Ada system when industrial operations are performed the information from the sensors is sent to a a controller or a number of controllers the controller is a type of computer that receives the information from the sensor now what happens with this information just depends on the environment and what's required and the sensor type it sends the information to computers with the seada software so this helps the systems monitor interact and control a variety of equipment prevents outside attacks the um seida systems are segmented from the rest of the network and in addition they have the firewalls installed you'd need probably help from a specialist and design company and probably installation as well because it's kind of outside the purview of the normal Network Engineers roles um old and outdated compute systems often referred to as Legacy these May well be running applications and you'll you could see this a lot if you do a new network Consulting you'll go to companies that are just running in Old software and they want to keep it because it still works and it's due to the cost and all of the heartache of having to upgrade and translate all of the data these systems can't be taken out of service usually but because of the age they're more vulnerable to attacks and because of the lack of support and the support means there's no more security patches so basically we'll come back into back to segmentation and it's important to segment these from the rest of the network service in the network for Public Public Access would normally restrict access this is classic example is at a public library where customers come in and want to use the systems but obviously you don't want them to have visibility to the back end systems where customers data is kept and people can get books and make payments and all that sort of stuff so you'd segment the servers and resources used by employees on a private Network public access to the public and net Network segmentations critical situations if a private network is restricted only to employees it's less prone to outside attacks probably certainly obvious here in a public network even if the server is compromised it won't actually affect your internal private Network so you could do your troubleshooting and resolution without worrying about um affecting your critical Business Systems uh testing patches and updates for applications should be carried out in a test the environment it's often called a test bed where you've got a copy of your devices and you could even be running them virtually and it's all done in order to prevent or foresee problems on your live equipment a honey pot is a decoy server set to lure attackers studies there and methodology and how they break into the systems gathers for our zinc forensic information and it can be used in the event that you actually prosecute somebody designed to be a little bit more easily exploited exploited than the actual production server so this would probably be the first device discovered by the attackers has attackers activities logged to get insight into their sneaky little methods okay an early part is a network segment that contains more than one um honey pot or only net sorry so the honey net would normally look like a normal operational Network for the attacker and it'll make the attacker spend more time in the system which gives you more time to analyze what they're doing and where they're coming from all right so we've covered segmentation physically logically uses of it and critical situations that's the end of the presentation thanks for watching [Music] Network routing and IP addressing IP addresses and conversion so welcome to this module we're going to cover IP addresses and conversions and in some of the previous modules we talked about a lot of the Technologies and theories and protocols that make up computer networks and so here we're going to discuss some of the more important aspects of networking specifically the IP address so this module is going to begin by introducing us to some of the specific protocols that are found within the tcpip protocol Suite that you need to know about for the network plus exam and these are TCP and IP and a little more depth we mentioned them briefly when we talked about the TCP model and then we're going to describe UDP which is a connection less protocol then we're going to look at ARP and rarp two versions that allow us to basically or two protocols rather that basically allow us to map Mac addresses to IP address and which are basically responsible for routing in general and after that we're going to look at two management protocols one called icmp which I introduced to you in previous modules and I said it was related to the Ping a utility we're going to learn a little more about that and then igmp which is uh slightly different has to do more with multicasting and unicasting and then we're going to continue by outlining uh IP packet delivery processes and we're going to finish off the module with a bit of an introduction into binary and decimal conversions so that later on we can talk a little more in depth about IP addressing and how something called subnetting Works which is going to require us to understand the difference between these two ways of writing our numbers and after we have covered all these topics we're gonna have a fundamental understanding of Ip that's going to prepare us for some of the more in-depth topics as I just mentioned in the following modules so let's begin by taking a look at two of the most important protocols that make up the suite TCP and IP now in previous chapters we briefly described these two but we still need to take a closer look at them to assure that we have a complete understanding of the many different protocols that are found in our protocol Suite so first for those applications and instances that depend on data to be reliable in terms of delivery and integrity the transmission control protocol or TCP and I'm just going to write out transmission control protocol is a really Dependable protocol and provides a number of features first it guarantees that data delivery and besides um guaranteeing that delivery it also has a certain amount of reliability it also offers flow control which as we've mentioned in the past assists ascending station in making sure it doesn't send data faster then the receiver can handle this function also is going to assist in the reliability of data because it ensures that there isn't any data lost due to overloading um the receiving station now TCP also contains something called a checksum mechanism and what this does is it assists with error detection the level of error detection isn't as strong as that of some of the lower layers and you recall that this is in the transport layer of the tcpip stack but it does catch some specific errors that may go unnoticed by other layers and and by the way this checksum basically it's it sort of has a number that it creates based on the data and it can check that number at the beginning and at the end to make sure we haven't lost anything now this protocol attempts to alleviate MTU if you recall uh what we talked about with MTU there mismatches on the data link layer by establishing maximum segment sizes that can be accepted by TCP this is also going to reduce what we talked about earlier that MTU black hole now further examining IP or the Internet Protocol which is aptly name and exists at the internet layer unlike TCP IP is characterized as being connectionless or a best effort delivery which is also like UDP which we'll see in a second it outlines the structure then of information which is called datagrams or packets and how we're going to package this stuff to send it over the network this protocol is more concerned with source to destination navigation or planning or routing as well as host identification and data delivery solely by using the IP address so this is slightly different from TCP which is doing stuff in a much more different way now IP is used for communications between one or many IP based networks and because of its design it makes it the principal protocol of the internet and it's essential to connect to it so unless we are using IP address in today's day and age we will not be able to connect to this big thing called the internet now the terms connection less and connection oriented relate to the steps that are taken before the data is transmitted by a given protocol whatever that protocol might be with TCP we're looking at connection oriented and of course with IP we're looking at connection less and for instance the connection oriented protocol is going to ensure a connection is established before the sending of data meaning it is oriented towards a connection whereas a connection less isn't going to doesn't matter if there is a connection established already so the next protocol which is also connection last that we want to talk about is something called UDP now since we have many applications and their functions depend on data being sent in a timely manner TCP and its connection oriented properties hinder their performance in these cases we're able to use something called UDP again the user datagram protocol and UDP is connection last just like IP is and it's a that means it's a best effort delivery protocol so with TCP if packets get delayed or if they're needed to be resent due to a collision the TCP on the receiving end is going to wait for the lost or late packets to arrive and with some sensitive data delivery this is going to cause a lot of problems and UDP is what we call a stateless protocol which prefers the packet loss over the delay in waiting so UDP is only going to add a checksum to the data for data Integrity it's also going to uh address port numbers for specific functions between the source and the destination nodes such as UDP Port 53 for DNS which is one that you should remember from an earlier module Now udp's features make it a solid protocol and it's used for applications such as VoIP or voice over IP and online gaming this makes sense because we don't care if every single little packet arrives what we want is we want the speed with which UDP is going to deliver stuff obviously if we miss a couple packets in voice that's okay they drop but we don't want to have to wait until the next packet arrives that's going to actually cause much more of a delay and so we're going to use this one in more VoIP and online gaming purposes now the next protocol we want to be familiar with is called ARP and it's also necessary for routing ARP or the address resolution protocol and the reverse address resolution protocol our request and reply protocols that are used to map one kind of address to another specifically ARP is designed to map IP addresses you need addresses that are necessary to tcpip communication to Mac addresses which are also known as we've discussed in the past as physical addresses and again IP addresses work on the networking layer or in tcpi PV internet layer whereas Mac addresses operate on the network interface layer of TCP which in OSI would be the data link layer layer 2. now in tcpipnetworking ARP operates at the lowest layer the network interface layer in total whereas in the OSI model we say that it actually operates between the data link layer and the physical layer and this is because it wasn't designed specifically for the OSI model it was designed for the tcpip model now ARP and rarp play very important roles in the way networks operate the computer wants to communicate with any other computer within the local area network the MAC address is the identifier that's used and if that device wishes to communicate outside of the local area network the destination Mac address is going to be that of the router so the our process works by first receiving the IP address from IP or the Internet Protocol then ARP has the MAC address in its cached table so the router has what are called ARP tables that link IP addresses to Mac addresses we call this the ARP table so it looks in there to see if it no if it has a MAC address for the IP address listed it then sends it back to the IP if it if it does have it and if it doesn't have it it broadcasts the message it's sent in order to resolve what we call resolve the address to a MAC address and the target computer with the IP address responds to that broadcast message with what's called a unicast message and we've discussed that that contains the MAC address that it's seeking ARP then will add the MAC address to its table so the next time we don't have to go through this whole process and then it Returns the IP address to the requesting device as it would have if it just had it now RP is used to do the opposite that is to map Mac addresses of a given system to their assigned IP addresses and it sort of works in Reverse from all this now that's a very general overview of ARP and rarp and if you were to go into Cisco certifications for instance you go a little more in depth into this but for Network plus this is really where we need to stop with this protocol so the next protocol I want to talk about is icmp which is also called the internet control message protocol it's a protocol designed to send messages that relate to the status of a system it's not meant to actually send data so icmp messages are used generally speaking for Diagnostic and testing purposes and they can also be used as a response to errors that occur in the normal operations of Ip and if you recall one of the times that we talked about that was for instance with the MTU black hole when that icmp message couldn't get back to the original router now many Internet Protocol utilities are actually derived from icmp messages such as Tracer or trace route path ping and ping and we'll talk about these in a little more depth than if you were around for uh a plus we definitely talked about these two quite a bit icmp is actually one of the core Protocols of the IP suite and it operates at the internet layer which as you recall is tcpip second layer now icmp is a control protocol used by networked computers and operating systems and the most common utility that we're going to see is what's called ping which we've talked about which uses what are called icmp Echo requests and they reply to determine connection statuses of a Target system so I could ping a specific system to see if it's on the network of course there are some reasons why the icmp as we've talked about might not make it back to me or it's configured not to respond perhaps through a firewall finally we need to talk about igmp or the internet group management protocol it should not be confused with icmp it's slightly different it is used to establish memberships for multicast groups now multicasting is where a computer wishes to send data to a lot of other computers through the internet by identifying which computers have subscribed or which ones wish to receive the data we looked at this earlier and determined that routers determine a multicast group now in a host implementation a host is going to make a request for and igmp implemented router to join the membership of a multicast group certain applications such as those for online gaming can use igmp for what are called one-to-many Communications the one being the game server and the many being all of those end users that have subscribed to the gaming session so those routers with igmp implementation periodically will send out queries to determine the multicast membership of those devices within range and then those hosts that have membership are going to respond to the queries with a membership report now the process of delivering an IP packet is simple it begins with resolving the name of the host to its assigned IP address like we talked about with arp and the connection is established by a service at if you recall the transport layer now after the name resolution and connection establishment the IP address is then sent down to the internet layer and the next step is where the IP looks at the subnet mask which we've talked about in a plus and we'll talk about more of the IP address to determine whether the destination is local to the computer on what we say is the same subnet or whether it's remote or on another Network after this determination is made then finally the packet is routed and delivered okay so we now understand TCP a little more fully some of the protocols that are dealt with in great detail and how IP packet delivery works so let's talk about binary and decimal which are going to be really important when we get into what's called subnetting and it's just good to know as an I.T professional anyway specifically understanding binary or how to convert binary which is the number of computers the way computers talk to decimal which is the way that we deal with numbers and decimal to binary pertains to a lot of different aspects of as I just mentioned networking so to begin with binary is the name implies from buy is what we call a base 2 system more commonly we used a base 10 system decimal now this means that we have 10 possibilities for every place value we have between a zero and nine you add that up there are 10. now with binary there's only two options either zero or one so we can either have a single zero or a single one and that's what we call a DOT a binary digit or a bit so the binary number has Place markers that are similar to the base 10 system for instance if we have a a decimal base 10 numbering system the second place Mark designates the tens if we imagine that there's a uh period or a decimal right there the third designates the hundreds and then we move to thousandths and ten thousandths and hundred thousandths and so on and so forth and in each one of these we can have anywhere from zero to 9 and that's ten options in each one of those spots now in base 2 numbering system which is binary we have only two options a one or a zero in either one of those places and in computers especially in a lot of Ip addressing we really deal with the difference between uh eight different places so we're going to call these eight and octet so this eight Place binary digit is referred to as an octet because there's one two three four five six seven eight of them and you'll see these numbers pop up over and over again so this is really as far as you need to know for binary although you can go even further so if we look at this octet from the right side to the left the first place Mark is what we call 2 to the 0 power right if we were talking about this in tens this would be the ones place y because it's 10 to the zero power which is ones anything taken to the zero power is one next we have 10 to the first Power which is going to equal 2. if you recall we call this the tens place 10 to the one power means 10 by itself is 10. then we have 10 to the second power which is 4 and if you recall in decimal this is 10 to the second which would be 10 times 10 which is 100 you can see where this is going so 2 to the third is eight two to the fourth equals 16 2 to the fifth equals 32 2 to the 6 equals 64 and 2 to the 7 equals 128. so each one of these Place markers is equivalent to this number whether it's turned on or off now to help clarify this a bit each place here has one of two options correct because it's base two if it's off that means it's a zero as you see right here and the numbered means it's not being counted so we don't count any of these numbers we've just calculated so if all the bits are off that means that we have a number of zero if all of the bits are on then this means we add each of the numbers together so we get 128 plus 64 plus 32 plus 16 plus 8 plus 4 plus 2 plus 1 which equals 255. now believe it or not you can create any combination of numbers from just binary you don't need decimal we're going to see that in just a second so for example let's say the binary number is uh zero zero zero zero zero one one one well in this case the 128 64 32 16 and 8 Bits are all off the only ones that are on are four two and one and if we add those together four plus two plus one we'll get 7. 4 plus 2 is 6 plus 1 is 7. if we take another number say 0 1 1 0 0 1 1 0. then this is going to equate to 102. why 64 plus 32 equals 96 plus 4 equals 100 plus 2 equals 102. so it's pretty simple you just take the number with the ones under it and add them together so now that we've converted binary into decimal a number that we all know let's go ahead and see if we can convert the other way decimal to Binary now for this process we're going to use the same exact chart that we just saw with the binary conversion and this chart is going to help us visually represent all the binary digits which is why I like it in their placeholders and it makes it a lot easier so for decimal to Binary we simply go from left to right and break down the number until we reach the zero so let me break that down a little bit for instance if we take the number 128 right this is pretty easy to convert we plug it into this chart how many times does 128 go into 128 one time if we take all the others and we subtract them we're going to have zero right because now 128 minus 128 is zero that leaves us with our binary number one zero zero zero zero zero zero zero which is equivalent to 128. now if we take a look at a different number let's say the number 218 this is going to take a little more math does 218 go in does 128 go into 218 it certainly does so 218 minus 128 has a remainder of a certain amount which is 90. does 64 go into 90 it does we now have a remainder of 26. does 32 go into 26 no it doesn't so we put a zero does 16 go into 26 yep it does which leaves us with a remainder of 10. does 8 go into 10 it does which leaves us a remainder of 2 does 4 go into 2 it does not so that leaves us with zero we still have our two does two go into 2 yep and then do we have anything left over nope we're at zero now so we have zero if we now add all those up this is our binary number one one zero one one zero one zero now while this might seem like a fairly long process it's important to understand how this works because when we get into subnetting it's really going to become important so we can have a better understanding of networking in general so just to recap everything we've talked about we described these protocols in the tcpip suite first TCP transmission control and IP Internet Protocol one is connection oriented and the other is connection less meaning that it just is worried about delivery remember IP is what is responsible for that IP addressing UDP is also connection less similar in some ways to TCP but it's not connection oriented then we had ARP and reverse ARP address resolution protocol which job is to map IP addresses to Mac addresses we talked about icmp which is what we use when we're dealing with the status of a system internet control message protocol and then we talk about igmp the internet group management protocol which is more dealing with multicast groups we then talked very briefly about the IP packet delivery process which was pretty simple right it's packaged it's sent we determine where it needs to go once it's determined where it needs to go it's sent there finally we explained the binary conversion which is going to be really important for IP addressing including how to go from binary which is a base 2 system to decimal which is a base 10 system and Back Again [Music] Network routing and IP addressing IP addresses and subnetting so having discussed IP addressing and routing in general we're now going to further examine IP addressing and the methods of logically not physically dividing up our networks this way we can keep not only better track of all the devices on the network but also organize them for security performance and other reasons after we complete this module we're going to have a better understanding of how our network devices are identified both by other devices and by individuals such as ourselves since we're not computers so first we're going to identify what a network address is versus a network name one the network address is for other devices a network name is really for us since it would be difficult for us to remember all these numbers much like using a phone number and a cell phone next we're going to describe the ipv4 addressing scheme and ipv4 is important to know because even though we have a newer version IPv6 ipv4 is still deployed in most situations and it's covered to the most extent on network plus when we get to IPv6 which is different version six there are a lot of benefits then we'll describe it later but really understanding ipv4 is really important after we take a look at that we're going to look at subnetting and a subnet mask you might have seen this and these are the numbers and we've probably mentioned to them in the past such as 255.255.0.0 and so on and so forth and we're going to describe how this allows us to separate out the network ID from the node ID or the device's ID or address from the networks address much like our ZIP code versus our street address after that we're gonna just describe the rules of subnet masks and their IP addresses and knowing binary is really going to help us understand all of this stuff after that we're going to apply a subnet mask to an IP address using something called anding which again gets back to Binary and might even remind you of something you learned in high school this ending principle which is really going to come in handy again this is something that we only have to do now with ipv4 IPv6 doesn't have to do it and we'll describe why finally we're going to take a look at what are called custom subnet masks which are slightly different from these default ones the 255 to 255 to 255s and so on so having said all that let's get into it by looking at Network addresses and names so let's begin by looking at how nodes on a network are identified specifically on the Internet or network layer if you recall the network layer is layer 3 of The OSI model and the internet layer is layer 2 of the tcpip model so to begin a network address is assigned to every device and I think we've discussed this that wants to communicate on a computer network the network address is actually made up of two parts the node portion that belongs to the specific device and the network portion which identifies what network the device belongs to I think I've just described this as a zip code which describes the sort of network or the area you're in versus your street number and your street address which is specific to where you live this address is what is used by devices for identification and as it's only made up of numbers whereas a network name is made up of um letters and such the real reason being readability we would have a lot of trouble remembering we already have trouble remembering a phone number but if you imagine remembering a whole binary number a set of numbers where there infinite possibilities unless you're using it a lot it's easier to remember a name such as the conference room laptop or resource server one than it is to remember an IP address which might be something like 132.168.56.43 especially when there are a lot more computers involved the names become a lot easier so the network named is actually mapped to the address or the IP address by one or another naming services and some of these we've discussed now as devices only communicate with each other by their Network address the naming service is a really crucial to the operation of a network there are three different network Services used that you should be aware of the first DNS which we've mentioned before also called the domain name service is an Aiming service that's used on the internet in most networks it's what allows for instance you to type in Google dot com which we would call a fully qualified domain name and it will translate that to the IP address of Google whatever that might be the next naming service is Windows specific and it's called wins or the windows internet naming service it's really outdated and it was used on Windows networks the only reason I mention it is you might see it mentioned in a test question and it might help you but you're really not going to see it used in the field much anymore and finally we have one called net bios which is a broadcast type of service that has a maximum length of uh 15 characters and it was used or still is used to a certain extent on Windows networks as well a good understanding of all of these Network identification aspects addresses and names is important at this very fundamental level so now that we sort of have a general overview of these let's take a look at some of the specific type of network addressing specifically ipv4 now ipv4 ipv4 addresses is a very important aspect of networking for any administrator or technician or even just you know it guy to understand it is a 32-bit binary address that's used to identify and differentiate nodes on a network in other words it is your address on the network or your social security number with the ipv4 addressing scheme being a 32-bit address and you can see if we counted each one of these up remember a bit is either 0 or 1 and we can count up there are 32 of these this means that there are theoretically up to 4.29 billion addresses available now that might not sound uh like we're ever going to hit that but in fact we've already gotten there and so part of the problem is how do we share 4.29 billion devices with our 4.29 billion addresses with even more billions devices in the world so this 32-bit address which is why we've had to develop another one called IPv6 but anyway I digress the 32-bit address is broken up into four octets this makes it easier for people to remember and to read and you can see those here and if you've ever seen like a 192.168.0.1 those are the four octets this system and structure of these address schemes is governed and managed by two standard organizations one is called the a i a n a which stands for the internet assigned numbers Authority and the other is called the rir or the regional internet registry I wouldn't worry about memorizing these I'm just mentioning them so you know sort of who's coming up with all this stuff now every device on the network is going to have its own unique address so there are two types of addresses in general one is called class full and these are default addresses and the other are called class less which are custom addresses we're going to talk about the class less ones in a later module and we're going to Define both of these in Greater detail a little bit later on as a network address it's also made up of two parts the network portion and the node portion let me just erase all this writing here so you can see exactly what I mean in order to tell now in this section you can see the network portion are the first two octets and the node portion of the last two octets but that is not always the case in fact if we were to just take those away for a second uh and this is how the computer looks at them we can't actually tell which is which and that's why we need something called a subnet mask the subnet mask allows us to determine which is the network portion and which is the node portion that way we know for instance where the area code of the phone number begins and the rest of the number ends so the network portion would be like the area code of your phone number or the international code it tells you which network that is on the Node portion tells you exactly which phone on that Network we're going to try reaching out to so we're going to further logically again not physically divide a network into smaller sub networks called sub Nets now this logical division is beneficial because of three reasons one it can effectively increase the efficiency in packet routing because if I know that my information is destined for a specific Network I don't have to bother with asking let's say 5 000 or 5 million or five billion computers if I'm meant for them I can go directly to the network where I want to go just like with area codes and phone numbers the next is it allows for better management of multiple networks within a single Organization for instance if I'm a network administrator it might be easier to have separate subnets so I can organize who's on which subnet so that way not only are things going to be routed more efficiently for that person but it's easier for me to manage on paper and uh in my administrative duties and finally it potentially offers a certain level of security since I'm only going to be able to access easily information that's on the same net work or sub Network that I'm on now a subnetted ipv4 address is actually comprised of three different parts the netid the host ID and the subnet ID now if a device on a subnetted tcpip network wants to communicate it's going to need to be configured with an IP address and a subnet mask and we'll look at these in just a second the subnet mask is what is used to identify the subnet that each node belongs to this also allows us to determine which network it's on connectivity devices such as routers or upper layer switches and we're talking about layer 3 devices here and remember layer 3 devices look at IP addresses not just Mac addresses are used on the borders of these networks to manage the data passage between and within the network that's how we're going to get better routing efficiency easier management and potentially make it more secure because if I have any one network and I have a let's say a switch we'll put this a switch and it has four computers on it and then I have another switch and these are layer 2 switches okay and each of these let's say we have our different subnets then I'm going to divide these up by a router which now is going to make sure that data that's going here kind of gets bounced back unless it's meant for this guy and this way we're really reducing the traffic on it now a subnet mask is like an IP address a 32-bit binary address broken up into four octets and a dotted decimal format just like an IP address and it's used to separate the network portion from the node portion I'm going to show you how that works in just a minute and it involves a little bit knowledge of binary which we've already talked about so the subnet mask and that name mask sort of lets you think of it as being put onto the IP address is applied to that IP address and removes the node ID the subnet mask therefore eliminates removes an entire octet of the IP address by using eight binary ones or 255 in decimal format meaning that this 255 if we add it up in binary would be one two three four five six seven eight one two three four five six seven eight one two three four five six seven eight and then this would be one two three four five six seven eight so meaning that a 255 equals eight ones which is the reason why an IP address can never be 255. and if this is a little confusing that's okay we're about to clarify that in just a second so IP addresses IP address assignments and subnet masks all have to follow a certain set of rules I'm going to describe the rules and then I'm going to apply them so if some of this is a little confusing or over your head keep paying attention keep with me and I think it's going to clarify itself the first is that the ones in a subnet mask will always start at the left meaning the first octet will always be 255 or 8 binary ones so my I my subnet mask I'm always going to start at the left when I'm writing it out this says that the first octet is going to be 255 which means 8 Bits now the zeros of the Mask will always start at the one bit or all the way on the right meaning that I'm going to have zeros from the right and ones from the left and the ones in The Mask have to be adjoining adjoining or con consistent or continuous or contiguous whichever word you want to use meaning once there is a zero we cannot then go back to ones so we're not going to see like this sort of thing happen in fact we have to have continuous ones from the left and continuous zeros from the right this is the only way a subnet mask is going to work and I'll talk about why in just a minute also if there is more than one subnet on a network every subnet has to have a unique network ID and I'll explain this in a bit but it makes sense if I have a different network IDs then I'm not really I'm sorry if I have similar Network IDs then I'm not really dealing with multiple networks I'm dealing with the same network now assignment of IP addresses have to follow a few more rules so these are the subnet masks first there cannot be any duplicate IP addresses on the network this means that every Network every device has to have its own unique IP address we cannot have more than one device with the same IP address if we do they're not going to communicate because the switches won't know where to send packets next if there are subnets every node must be assigned to one of them meaning that every address every IP address has to be assigned to a specific Network now the address of a known cannot be all ones or all zeros remember all ones would be 255. all zeros would be just 0.0.0.0 so I cannot have an IP address that is either 255.255.255 or that can be 0.0.0.0 and you'll see why when we get to the mathematics of this in just a second it's because then I would never be able to determine a network ID from a node ID finally and this is something you sort of have to remember the IP address can never be 127.0.0.1 we've talked about this in um a plus but that's because this is what's called the loopback it's a reserved IP address specifically for yourself be like saying me myself or I I cannot have a a 127.0.0.1 IP address assigned to a device because every device calls itself 127.0.0.1 now besides understanding these rules which are a bit abstract I think we need to know how to apply them and how to apply a subnet mask to an IP address I think it's going to make some of these rules a little clearer so let's take a look at those now when a subnet mask is applied to an IP address the remainder is the network portion meaning when we take the IP address and we apply the subnet mask and I'll show you how to do that in a second what we get as a remainder what's left over is going to be the network ID this allows us to then determine what the node ID is this will make more sense in just a minute the way we do this is through something called anding ending is a mathematics term it really has to do with Logic the way it works is and you just have to sort of remember these rules one and one is one one and zero is zero and the trick there is that that zero is there zero and one is zero and zero and zero is also zero so basically what anding does is allows us to hide certain um address certain bits from the rest of the network and therefore we're allowed to get the IP address or rather the network address from the node address so let's take a look at this for just a second let's say we have an IP address 162.85.120.27 and we have a subnet mask of 255.255.255.0 now let's take a look at how this works when we move it into binary 162.85.120.127 equals this in binary and if we wanted to write out these places again if you remember we had this was a base two right so these are the place settings I'm just going to write these out real quickly and then I'm going to erase it all okay and so we get one two four eight sixteen thirty two sixty four 128 and it's good to sort of commit these to memory therefore the reason this is one one one is we take that 128 we add it to 32 and we add it to the 2 because those are the bits that are on and when we add 128 plus 32 we get 160 plus 2 gives us 1 62. so it works out and you can see my math is correct here I'm going to erase all this now try to remember this and thing in here for a minute now if we convert 255.255.255.0 into binary we've already talked about this we're going to get all these ones and then because this is zero we're gonna get zero now if we apply the anding principle this is what we're going to get anything with one and one turns into one anytime we see a one and a zero we're going to get a zero and if we apply this out here's what we get now because we have all these zeros here it's basically going to block all these ones from coming down and coming through right they all turn into zero so if we convert this back into a decimal we now get 162.85.120.0 basically this is pretty simple to see we can see that the 162 drops down the 8 5 drops down the 120 drops down because of this ending that we just talked about and the 27 gets blocked might be zeros and so we can determine that the 162.85.120 is what we call the network ID Now by looking at it this way we can see then that the network portion of the address is going to be the first three octets as we just pointed out and the node portion is going to be the last octet so this is the first step in subnetting and it tells us a lot of things about the networks just by knowing the IP address and the subnet mask a technician can now discern a lot of things such as what portion is the network ID what portion is the node ID and therefore what is my first usable IP address and what's my last usable IP address that I could start to give to devices I can also determine stuff like what we call the default gateway which we'll look at in a second and the broadcast address which will also look look at not in a second then in the next module now there are three default subnet masks as you can imagine and these have to do with what we call a class uh a class full IP addressing system and we'll talk about that next the next module but the default subnet masks are 255.0.0.0 just going to go with the class A and we'll talk about that 255.255.0.0 and 255.255.255.0 what you can see is if you have a default subnet mask then you know immediately just by looking what the network address is and what the node address is as you can imagine if I have this as my network address I can have a lot of Networks and only so many nodes this one I have more nodes a little bit less networks and this one I have a lot of nodes but fewer networks to divide them up on now would be great if all subnet masks were as simple as this we wouldn't even really ever have to break it down into this binary sort of coding because you could just look at it and say oh it's 255 I know they're all going to be ones I know that's going to end out and therefore I know it's going to end up right here but unfortunately this is not always the case sometimes we have what are called custom subnet masks Now by using a custom subnet mask we can actually further divide or subdivide our IP address and in these cases it can be a little more difficult uh and so converting to Binary is actually necessary to break it down custom subnet masks are created by what we call borrowing bits from the host portion to use to identify the subnet motion so you can see we've just borrowed a bit this one right over here now keeping in mind that the subnet mask rules allow us to borrow bits from the node portion and give them to the network portion the bits from the left to the right of the portion like this are switched on now turning this bit on means we now have different values for the subnet mask instead of just 255 .255. 255. dot zero we know this is no longer zero right so this is actually now going to be 128. and we can have a a number of these and if you keep adding over to the right so 128 and then we added 64. we'd get 192 and so on and so forth so we can actually have a number of custom subnet mask values in the last octet and that's those are these and so you can see in this case uh it's not really going to make much of a difference when I I'll do all the binary bidding because you see that the zero and the zero is still going to become a zero here and so all of this is really going to look the same and so our Network portion is actually going to look the same as it did before we have the same network ID as we did before but let's say that this was actually uh you know this number by the way is the same as the one we had before 162.85.120.27 if this was instead 162.85.120 dot I don't know one 128 we're gonna have an issue because this is going to be on these would say let's be off and when they come down this is going to turn into a zero as opposed to that one dropping down and so it's going to change what our IP address in the end looks like and so we actually need to do some backward engineering to get to our subnet mask now this is all really complex and when we get into if you ever get into Cisco you'd really have to know this but for our purposes you really don't need to know this that in depth all right so just to recap what we talked about here we got a basic understanding of a lot of things not too in depth and you might need to re-watch this video to really get it and maybe even do a little bit of exercises on your own first we talked about the difference between a network address and a network name remembering that the three network name services that match a name such as Bill's laptop to an address which would be something like 192.168.0.1 uh we can use either DNS the domain name service which is the most popular one something called wins which is specific to Windows or net bios also a Windows based naming system the one we want to be most familiar with is this this one's not really used anymore netbios is still used in certain instances especially in older networks we then talked about the IP version 4 address and the things that it requires including and remember a ipv4 address is that 32 bit broken up into four octets the reason it's called an octet is because we have eight times four gives us that 32 and we break it up so for instance 192 is going to break down to a certain amount of bits okay we also talked about defining subnetting in a subnet mask which the most important thing it does is distinguishes our Network from our node ID in other words what's our area code and then what is our phone number we can have the same phone number in different area codes but they go to very different people we also talked about the rules of subnet masks and IP addresses we can only have one IP address on any network and we can not use 127.0.0.1 because that is what we call the loop back address as far as for the subnet mask remember that all ones have to be continuous from the left and zeros have to be continuous from the right our defaults our 255.255.0.0.0 and then 255 I'm sorry I think I just said 255.0.0.0 285.255.0.0.0 and 255.255.255.0 those are our defaults and so we talked about applying a subnet mask using something called anding and we looked at how that divides up again the network ID from the node ID and we saw that in practice finally we talked very briefly about custom subnet masks something that we don't have to get very much into but we talked about how if we had 255.255 .255 dot for instance 128 we could have these sort of sub subnets or these uh we could break it down even further and therefore we could start to do a lot more stuff and in the next module I'm going to talk about this in a lot more detail and why we would want to do it [Music] thank you Network routing and IP addressing default and custom addressing so we described in the previous module subnetting how to determine the network from the node ID and we talked specifically about ipv4 and we're going to continue talking about ipv4 a little bit more first by defining the default ipv4 addressing scheme now some of this we sort of touched on in the previous module and some of the stuff we're going to talk about right now is going to probably help clarify that and so it might not it might even help to go back and watch the previous module after watching this one after that we're going to talk about the reserved or restricted ipv4 addresses one of the ones we've already mentioned is what we called the loop back or 127.0.0.1 that's an example of a reserved IP address a restricted IP address and so we're going to talk about those in more depth and some of the ones that some of the ranges that are restricted and why they are then we're going to discuss what are called the private address addresses and we're gonna talk about these specifically because these are different from public IP addresses uh one you might be familiar with is the 192.168 uh public at a private addresses rather and you'll this is going to explain why every router that you purchase that you know electronics store has this as its default not everyone but a lot of them have this is the default IP address and yet we talked about how you can't have more than one IP address with any device and so we're going to describe why with private IP addresses this is the case and we'll talk about some other private IP addresses as well now we're going to talk about the ipv4 formulas and that's the that's what allows us to determine how many hosts and networks are permissible based on the type of IP address the class that it's in and the subnet mask that's supplied and this will help us also determine and talk about in a second uh why we might want to use custom subnet masks and custom IP addresses so then we're going to talk about the default gateway is this gets back to actually this right here it is the device which the any node needs to know in order to get out to the network and to the rest of the um the rest of the world finally we're going to talk about custom IP address schemes vlsm and cidr these are a little more in depth but these really get back to the subnet masks and why we can apply those uh how we can apply sort of specific subnet masks to things and we'll look at this thing which you might have seen cidr which is has to do with why there might be a slash after an IP address which really gets to the number of bits it has and we'll talk about that just a minute now aside from being an aspect that's covered in many areas of the network plus exam understanding the classes in a default IP address scheme is really important for us and this gets back to uh right here so let's talk about remember we talked about class lesson class full we're going to talk about the classes that exist in an IP address right now so as we learned in previous modules the ipv4 addressing scheme is again 32 bits broken up into four octets and each octet can range from 0 to 255. now the international standards organization icann which we've mentioned in a previous module is in control of how these IP addresses are leased and distributed out to individuals and companies around the world now because of the limited amount of IP addresses the default ipv4 addressing scheme is designed and outlined which what are called classes and there are five of them that we need to know now these classes are identified as a b c d and e and each class is designed to facilitate in the distribution of IP addresses for certain types of purposes now the First Class A Class A allows you to have is designed for really large Networks meaning that it does not have a lot of networks because we only have a few of them and that is because a Class A Range goes from one to 127. in the first octet meaning that the remaining octets are reserved for nodes and so we see that we don't have a lot of networks we only have 126 networks one to 127. but we do have up to 16 .7 or 0.8 around about million net I nodes that can be on this network and so uh we have so many nodes for so few uh networks and so this is really for very large large networks and there are some specifically reserved addresses in this as well we'll talk about those in just a minute now with class B here we have 128 to 191. and these are called Class B they allow for a lot more Networks and fewer nodes which makes sense Now the default subnet mask for class A which might make this a little clearer 255.0.0.0 whereas for a class B it's 255.255.0.0 now as you can tell the class is actually determined by the very first octet the number in the first octet and it's important to then therefore memorize these numbers because you'll see on your exam they'll ask you which class is this IP address a part of if it's between 1 and 127 you know it's a Class A if it's between 128 and 191 you know it's a Class B if we get to a class C now we have a lot of networks and not a lot of nodes and you can see that these are 192 to 223 in the first octet and the default subnet mask for this is going to be 255 to 255.255.0 and if you remember that gives us only this octet for nodes and all of these octets for networks this is usually one of the most recognizable for home networks because we have the 192.168.0.1 for instance that is going to obviously fall into this class C now there are two other classes they're not very common but they're important to be able to recognize they're a Class D i p addresses which are only used for what we call multicast Transmissions and these are for special routers that are able to support the use of IP addresses within this range you don't really need to worry about this for much application unless you're dealing with a lot more advanced stuff and these deal with 224 to 239 finally we have class E which is from 240 to 255 and these are really for experimental reasons so we're really not going to see these in much play the ones you really want to be familiar with are these first three classes a b and c remember 1 to 127 is a class A 128 to 191 is a Class B 192 to 223 is a Class C if you can remember those ranges I would commit them to Memory you'll be good to go for the exam now within each of these classes there are a number of addresses that are not allowed to be assigned or leased for specific reasons these are what we call reserved and restricted IP addresses now we've mentioned the 127.0.0.1 or the local loopback or the localhost i p address before which can't be assigned because it's reserved for me for myself from for I this means that this address is used when I want to address myself so if I wanted to for instance assign myself my own name via DNS and my name was me me would link up to the IP address 127.0.0.1 and that way it's going back to myself now we're really going to use this for mostly diagnostic purposes if I want to double check to make sure for instance that tcpip is running correctly and it's also going to be used for programmers and such like that now the address 10.0.0.0 is also restricted and it's not available to use because again this a host address can never have all zeros conversely the addresses that have all ones for instance 255.255.255.255 cannot be used for um uh addresses obviously this one can't because it would sort of ruin the use of a subnet mask but even if I had something like 192.168.0.255 I can't use that because that's what's called a broadcast address and so it's just simply reserved for that this means that if a message is transmitted to a network address with all ones in the host portion or 255 that message is going to be transmitted to every single device on the subnet it's called a broadcast and we talked about broadcast before finally the address 1.1.1.1 cannot be used because this is what's called the all hosts or the who is address so these basically what whereas 127 is for me 1.1.1.1 is for everyone so these we can never use the important one I really want you to remember here is this one and you're going to want to remember that for instance 255 in the host portion can never be used again not only because that's going to ruin a subnet as we've talked about but also this is reserved for what's called a broadcast address now there are portions of each class that are allocated either for public or private use private IP addresses are not routable this means that they are assigned for use on internal networks such as your home network or your office Network when these addresses transmit data and it reaches a router the router is not going to uh route it outside of the network so these addresses can be used without needing to purchase or leasing an IP address from your ISP or Internet service provider or governing entity so this is how I could create an internal Network in my home and I don't need to go register it and I might not be able to access the internet but I don't need to register if I want to go out to the internet then I can share using devices and resources we've talked about previously and we'll talk about later a public IP address with all the internal devices that are configured using private IP addresses now since these are not able to be used externally to our Network these IP addresses can be used by as many devices as necessary as long as we never double over one IP address per device so the class a private IP address range remember we talked about 10.0.0.0 because we cannot have zeros right remember 10.0.0 and 285 we actually cannot assign but any address in between that so 10.1.126.5 would fall into what's called a private address range and you might see this in your home router as well so this makes it easily discernible from other addresses in its class anything that has the 10 to begin with cannot be used on a Class A Network or any network except privately we also have a class B uh Private Exchange which is 172.16.0.0 through 172.31.255.255 and Class C which is 192.168.0.0 through the 255 to 255. this one you might have seen the most this one I'm guessing you've seen the last this one's probably the second most common the 10 dot so if you have a internal Network at your home you might have your address on your computer right now for instance if it's not connected directly to the network if it's connected to a router might be something like this or like this or even like this all right that's because these are each private addresses it's important that you commit these to memory as well because these will appear on the exam and remember the important thing with a uh with a private IP address as I mentioned right here is they're not routable and I don't need a lease to use them so when tasked with subnetting a network you need to understand how to calculate how many hosts and how many networks are available if we want to determine the number of hosts that are available we apply this Formula 2 to the x minus 2. and this is where X equals the number of node bits and that's after we break it down from decimal to binary now the reason for the minus 2 here is because again we cannot use a DOT 0.0.0 address or a.255.255.255 address which would mean all zeros are all ones in the subnet and so we need to make sure uh rather in the um uh in the bit right when it's broken down and so we need to make sure that um this is the case we also need to know the number of networks and to do that we're going to do 2 to the Y minus 2 where y equals the number of network bits so let's take a look at this if we have the IP address 162.85.120.27 and we have a subnet mask of 255.255.255.0 by the way we can look at this and we automatically know that 162.85.120.27 this looks like a class b i p address and the 255 the 255 to 255 is actually our default Class C subnet so this is not the default that we're working with here so we need to figure out uh some information here so let's break it down into bits and I'm do that here and if you wanted to check my math you could now the number of network bits is right here the Y and the number of node bits is right here the X so if we pop this into our equation the number of possible hosts we have is 254 and the number of possible networks is over 16 million if we go back to that table we saw a few slides ago we'd see then that that's why we have a default for class B and Class C networks is we can see how many networks are possible and how many hosts are possible now why would I want to know this well let's say that I have to divide up my network and I want to have a certain number of networks in a certain number of hosts well if I only need five networks but I need 30 000 hosts I'm going to be in major trouble here because now I have to divide this up so much I'm wasting a lot of networks and I don't have enough hosts so we want to determine how we can do this to reduce the amount of waste we're going to talk about that in just a bit going back to something called a default gateway for a second device that wants to connect to the internet has to go through what's called a default gateway this is not a physical device this is set by our IP address settings it is basically the IP address of the device which is usually the router or the Border router that's connected directly to the to the internet for instance we had other routers in here this is going to be the Gateway and so three things need to be configured on any device that wants to connect to the internet we've talked about it we need to have an IP address a subnet mask and this is the new one a default gateway so this is the device that's used when I want to communicate with the internet and it's not used when communicating with devices on the same subnet this is why it's called a Gateway think about it as your gateway out to the network most often and more often than not as I mentioned this is going to be the router so if you have at home for instance a router that's 192.168.0.1 that is also your default gateway and if you went and did an ipconfig all something we'll take a look at later and command prompt you'd be able to see then your default gateway is this address basically it means hey I don't know I want to get up to the internet I don't know how to get to Google I'm going to ask my default gateway the default gateway then takes care of everything else and then the information comes back and it sends it out to you again now there are a couple different ways of implementing custom IP addresses we previously described how we could use custom subnets and with that method a custom subnet mask and an IP address is what we call anded if you recall and together they allow the node to see the local network as part of its larger Network now each customized subnet is configured with its own default gateway allowing the subnets to be able to communicate with each other now another method of doing this is called vlsm or variable length subnet mask and by using this we're going to assign each subnet its own separate customized subnet mask that varies now the VLS MF it allows for a more efficient allocation of IP addresses with minimal address waste which I was just talking about so for example let's take a situation in which a network administrator wants to have three networks and I have a class c space now just so you know some of this is very outdated and we're not going to see it used a lot of the time that being said Network plus really wants you to know about it so we're going to cover it so I know I need to have three different networks or sub Networks and I know on the first Network I want to have four hosts on the set network I want to have 11 hosts and on the third network I want to have 27 hosts now in order to accomplish this I could use the subnet mask 255.255 the 255.20 that 224. and for each of these subnets if I was to add this out right one two three four five six seven eight that's 255 one two three four five six seven eight that's 255 one two three four five six seven eight that's 255 let's write 224 in bits all right let's go through our calculation again here I'm just going to do this because it never hurts to do this a couple times so let's write all of these out great all right we have one two four eight sixteen 32 64 128. now we remember that subnet masks have to have continuous ones so that's 128 128 plus 64 is 192 plus 32 is 224. so then if we broke this down into bits this is what it's going to look like okay so let's write that out here and if we do our calculation we know we need to have how many hosts when we need four so let's do our calculation 2 to the 1 2 3 4 5 power right we're going to figure out how many hosts that equals we already know it's 32. minus 2 means that we can have up to 30 hosts on this subnet so I'm wasting an effect 26 addresses on this subnet 19 on this one and three on this one I'm not really doing a good job because I've had to apply the same subnet mask to every single IP address and in doing so I'm wasting a lot of my possible addresses now if I used vlsm instead it's going to erase all this I could do 255.255.248.240 and.224. now remember uh 248 if we route that out I'm just gonna really quickly all right and you can double check my math here if we do 248 that is going to be one one one one one one zero zero zero all right and then if we do our calculation two to the 3 because we have three host bits what does that equal eight minus two well now we have a possibility of six hosts so what is our waste two because six minus four equals two a lot better right if we do the same thing with uh the next one and you were to do the same thing I just did that would look one one one one zero zero zero zero we did the calculation again two to the four because now we have four bits minus two which equals 16 minus two which equals fourteen so now I'm only wasting three bits because 16 sorry 14 minus 11 equals three and finally 224 is the same remember that was 30 bits or 30 hosts rather 30 minus 27 is 3. so doing this variable we are a variable subnet mask we're no longer wasting as many host addresses so by utilizing this we're going to appropriately plan and Implement a scheme and it allows us to use our space much more effectively of course the negative aspect of this is it's a lot more harder to scale and if I want to add nodes to these customized networks I might have to go around and change all the subnet masks as well now cider which is cidr which stands for class less enter domain routing is also commonly called super netting or classless routing it's another method of addressing that uses the vlsm but in a different way is at the 32-bit word so the notation is much easier to read because it combines the IP address with this Dash after it for instance the number is what denotes the amount of ones in the subnet mask from left to right so if we look at this notation right here we have 192.168.13.0.23 well the 23 means there are 23 ones from left to right in the subnet mask okay and now if we were to convert that this allows for a possible amount of host addresses 2 to the ninth minus two which equals 500 and 10 addresses so this allows for more than one class full Network to be represented by a single set basically we can now break it up further into smaller sub networks if we look at three of the most easily recognizable ones I'm just going to erase this so we can get a better look here uh the slash eight the slash 16 and the slash 24 we can see that these translate basically over to the basic Class A Class B and Class C networks right because slash eight Class A that means it's one one or one two three four five six seven eight dot zero dot zero dot zero which would mean 255.25.0.0.0 which is our default subnet mask for Class A because again this is my network ID is the first octet and the node ID are the last ones and you can see that that would fall out for the next ones as well so because of the ease by which it is we can subnet networks this way because of readability and efficiency cider notation has become extremely popular and wider widely adopted most of the internet in fact has become class less address space because of this meaning that we don't really use classes and we get to IPv6 we're not going to see it at all now again this is very complex the important thing I just want you to remember on this whole thing is that if you see this Dash after an address here you know exactly what the subnet mask is and then you can backwards engineer or forward engineer the IP address or the network ID or node ID so just to review some of the points that we covered here we started by outlining the ipv4 addressing scheme we looked at the five classes the three I really want you to be aware of are a b and c remember a is anything in the first octet that's one through 127 with class B we're looking at anything from 128 to 191 and with class C we're looking at anything from 191 or rather 192. to 223. anything else here we're really looking at experimental and stuff that we don't really need remember these ranges for that first octet it's easy then to determine what class we're looking at okay so we also described the reserved or restricted IP addresses for instance we can't have anything with a zot 0.0.0 or with a 255.255.255. because these are a multicast addresses and we also can't have anything with 127.0.0.1 ever or 1.1.1.1 because these are both ones the localhost one is the who is address we then looked at uh private IP addresses remember we had three different ones each for each class for class A it was anything 10.x.x.x with class B it was one seven two dot sixteen dot x dot X through 172.31.x.x and the one you're probably most familiar with is the class C which is 192.168.x.x remember that you can see what class they're in by looking at this and most importantly class a private IP address can allow for the most networks the fewest I'm sorry the most nodes the fewest networks Class C is going to be the complete opposite I'm going to allow for the most nodes the most networks rather but the fewest nodes okay and again remember these ranges because they will come up what is make a private IP address it is not routed past a router onto the public network okay we also talked about the ipv4 formulas which allow us to determine how many hosts or how many networks are allowed on a network and that is where the x or the y equals the number of hosts or network bits we defined the default gateway which is what I need to get out to the WAN it's what a local device a node on the local area network needs to go to this default gateway and finally we Define the two custom IP address schemes the one which allows me for variable subnetting and the other cider which allows me to use a slash and then put a number that number representing the number of Network bits in the subnet mask right so the most popular of course 24 would be for a class C 16b for a class B and 8 would be for a class A because if we had a slash eight that would mean the subnet mask is 255.0.0.0 [Music] foreign Network routing and IP addressing data delivery techniques and IPv6 now we've talked a lot about IP addressing when it comes to ipv4 or the Internet Protocol version 4 but fairly recently IPv6 or IP or Internet Protocol version 6 was released and has now begun to be implemented across the world in every Network situation so in this module we're going to discuss the Core Concepts that are involved with IPv6 addressing and some of the data delivery techniques as well so at the completion of this module we're going to have a complete understanding of the properties of IP version 6 or IPv6 and we're going to be able to differentiate between IPv6 and ipv4 which is the one we've been talking about up into this point as a reminder ipv4 is that IP address that is 38-bit 32 bits and divided into four octets and we're also going to outline some of the improvements in the mechanisms of IPv6 and why we needed to have another version of Ip addressing we're also going to cover the different data delivery techniques as well as what a connection is different connection modes and we touched on these briefly such as connection oriented and connection less and they're transmit types finally we're going to go further into data flow or flow control which we've talked about a bit and we've mentioned a bit buffering and data Windows these are all techniques that allow data to be sent over a network in varying ways and finally also we're going to talk about error detection methods that way we know when data arrives on the other end we can double check it to make sure it is the data that was in fact sent so in the last module we learned about the ipv4 addressing scheme and we talked about some aspects of How It's implemented now IPv6 is the successor to ibv4 and it offers a lot of benefits over its predecessor the first major Improvement that came with this new version is that there's been an exponential increase in the number of possible addresses that are available several other features were added to this addressing scheme as well such as security improved composition for what are called unicast addresses header simplification and how they're sent and a hierarchical addressing for what some would suggest is easier routing and there's also a support for what we call time sensitive traffic or traffic that needs to be received in a certain amount of time such as voice over IP and gaming and we're going to look at all this shortly so the IPv6 addressing scheme uses a 128 bit binary address this is different of course from ipv4 which again uses a 32-bit address so this means therefore that there are two to 128 power possible addresses as opposed to 2 to the 32 power with um IP address 4. and this means therefore that there are around 340 undecilion I'm going to write that out so that's a word that you probably haven't seen a lot on decillion addresses and to put that another way it's enough for one trillion people to each have a trillion addresses or for an IP address for every single grain of sand on the earth times a trillion Earths give or take a bit so if the 128-bit address were written out in binary it would be 128 ones and zeros because that is binary and even in decimal form that's a pretty hard to read and keep track of so because of this we use what's called hexadecimal as the format in which uh IPv6 is written and if you imagine from the name hex uh binary is a base 2 system meaning that we take everything to the power of two so we have the ones place and then we have the two place and then we have the fourth place and so on and so forth with decimal which is a base 10 system we have the ones place the tens place the hundreds place which is ten times ten the thousands place and so on with hexadecimal though we're looking at a base 16. so every single digit has a possible 16 different options so we'd have a ones place which we always start with a ones place and then a 16s place and then so on and so forth now the way we do this is that every digit as opposed to decimal where we have zero to nine options for every digit and binary where you have either zero or one with hexadecimal we can either have zero to nine or a through F if we add this up we have 10 options here 0 through 9 and then a through F we have six so a hexadecimal number is going to be a combination of anywhere from 0 to f uh a would be 10 B would be 11 C would be 12 and so on and so forth so when you see uh this written out that's what that means okay now the address is broken up into eight groups of four hexadecimal digits and these are separated by colons now uh I'm going to show you this in just a second but there are also a couple of rules when it applies to when we come to readability so the first rule is that let's say this is our hexadecimal IPv6 address you notice first of all one two three four five six seven eight right there are eight groups of four hexadecimal digits each and of course each one of these digits has 16 possible values okay so let's look at two rules and these are also not only readability rules but what we call truncation rules meaning this is how we can shorten an IPv6 address since they can get quite long the first rule is that any leading zeros can be removed so if we imagine any leading zeros I'm going to circle them right there right here right here and if we wanted we could even consider these leading zeros and therefore if we rewrite this out below you'll see we're going to remove all the leading zeros and that allows us to shorten our address now we could also if I was just going to take this one step further I could also shorten these zeros if I so wished and just leave one zero there now no matter how you write out the address the rules are put in place in a way that you can always go back to the main address and so you don't have to worry about you know you can sort of pick and choose there are best practices but the computer is always going to be able to figure it out okay now the second rule is that successive zeros or successive sets of zeros can be removed but they can only be removed once so any sets of successive zeros and here we see one set or two sets rather successive zeros can be removed and replaced with a double colon now the reason we can only apply that once is let's say these zeros were we had another set of zeros over here and we um truncated those we can add up right we know there's one two three four five six sets here so we know that this represents two sets of missing zeros but for instance if we had you know two other sets here and we remove those we might not know whether it's supposed to be one set and three sets or two sets and two sets and so on and so forth so we can only do this once because when we add them back there's no way to know um uh you know where that would sort of lie now uh I'm just gonna erase this for a second because we can even truncate this more we've applied this rule so this applies this rule this one is applied this rule but we can apply both rules right so we can remove these leading zeros here and actually write this out as 2001 d8 eight eight a three double colon which means that those are successive zeros three e seven zero seven three three four now let's just I just want to uh sort of follow up and explain write out what I was just talking about with why we can't have more than two sets of successive zeros okay let's say that we have zeros here as well okay so I'm gonna rewrite this out we have zero zero zero zero colon zero zero zero zero colon zero eight A3 colon zero zero zero zero zero zero zero zero eight c three e zero zero seven zero seven three three four okay let's first apply our first rule which is that leading zeros can be removed so we rewrite this and we're going to get this okay now we're allowed to remove one set of leading of successive zeros only which is the second rule okay but let's do it twice and just see what happens so let's say we have a double colon here 8a3 and then we have another double colon 8c3e seven zero seven three three four now let's say we want to expand this back out to its full version well if we have the successive zeros here we don't know if this would be written out zero zero zero zero dot 883 because from what we're seeing here theoretically we could put three zeros here and one zero here right or we could do it the other way around so the reason we can only do it once is because then mathematically we know exactly how many belong when we do that all right so hopefully that helps clarify the reason behind the success of zeros being removed all right now uh what this also means is that if you remember a loopback address an ipv4 the loopback was 127.0.0.1 while we also have a loop back when it comes to IPv6 that's all these zeros to one but because we can apply all of these rules we can truncate this to Simply this all right so uh this is important to remember these rules are important to remember the other thing I want you to remember is that hexadecimal zero to nine a to f so they might show you something and say which of these is not a valid IP if it has a letter say G or an H then you know it's not going to be valid and here we can check here's a d That's good here's an a that's good C good e good so this is good to go right if we had an H or a g or an X for instance then we would know that the um IPv6 was incorrect because there's no hexadecimal symbol X so the ipv4 addressing method is is really different from IPv6 addressing and it's comparatively it's lacking in many areas first as we've talked about we're using a 32-bit binary address in ipv4 versus a 128-bit binary address in IPv6 and of course this greatly increases the number of possible IP addresses I think around February of 2011 all of these IP addresses had been leased and uh so there weren't any addresses left I think we had something right like 4.8 0.7 billion right and all those were gone and so we were depleted of all of our IP addresses so this is why we had to transition to IPv6 because now we have that undecillion uh address which again is if every there were a trillion people they could each have a trillion addresses now another major difference between these two is that uh ipv4 utilized the classless inter-domain routing notation if you remember which had that slash and then a number of bits well in IPv6 this isn't necessary and IPv6 actually has a subnet size of 2 to the 64 power now if you remember that the total IPv6 is 2 to the 128 then what you realize is that the first half of the IPv6 address so if we were to write one out again let's say 2 0 8 a 3 6 4. uh nine two B f one zero zero zero right okay so then we're gonna have four more on this side the first four which again is the first 64 bits that's the subnet so now we've integrated the subnet into the IPv6 address which is the benefit now we don't have to sort of have this extra uh uh written out cidr thing so it's been standardized it's always 2 to the 64. we always know the subnet or the network node is on the first section and the node ID is on the section the second section the other two to the 64. so this really help helps us simplify things to a great extent now obviously one of the issues is we're going to under use a lot of the addresses we're going to under use many of our addresses because we're never going to have to really use this many subnets or perhaps not even that many networks right but um there are so many other benefits that it has with routing and efficiency and simplified management that it it sort of um makes up for it and so that's why we're going to make that sacrifice now in terms of domain name systems uh with DNS when we talked about for instance a google.com going over to say you know whatever that IP address is I'm making this one up obviously it's not a real one because we're in a private IP but this was called an a record right so a server would have something or a DNS server would have something called an a record and that a record had this information in it all right now when we're dealing with IPv6 we're utilizing a quad a record for this mapping now we can also use the same a record but this quad a record can be used as well so if you see Four A's what we call a 4A record or a quad a record then you know we're using IPv6 it's one of the differences and again these are the records that are used to map IP addresses to what are called fully qualified domain names now while comparing these two schemes also ipsec which stands for IP security is another aspect that we need to consider in ipv4 ipsec is optional it's widely used for secure traffic over ipv4 Communications but when we dealt with IPv6 ipsec was designed for it and so uh it's required from the original specification and therefore all Communications that are working over IPv6 are automatically falling under ipsec so it can be considered in some ways optional I guess but it is required use from the get-go because it was built into IPv6 now the IPv6 scheme can also handle a much larger packet size the packet size for ipv4 is 65 535 octets payload when we get to IPv6 we're dealing with a 4.295 billion octets of payload so obviously these are a lot bigger these are what we call jumbo grams as a result you can imagine that if we want to deal with ipv4 and we're on an IPv6 Network we're going to have to make up for this now if you recall we were talking about ethernet we also were talking about the header sizes and all the information that was contained in there well the header size for ipv4 and IPv6 is also very different which actually makes these two protocols not compatible with each other so IPv6 is not compatible with ipv4 and so the way we're going to communicate with an IPv6 over an ipv4 network if we need to is by tunneling the packets in other words we take an ipv4 packet I mean an IPv6 packet and we literally wrap it around where we wrap around it in ipv4 packet and so we tunnel the IPv6 packet inside of the ipv4 now this allows it to communicate but this is also what we call a dual foreign in some cases we can have what's called a dual stack where we have an ipv4 and an IPv6 and so we can choose which one to go over and then this tunneling is not going to be necessary now we don't really want a tunnel because obviously the payloads are so much different in size that it's going to cause all sorts of trouble so what we'll try to do is create this dual stack in which we have one network and the other and they're both operating sort of side by side if we can't do that then we have to use tunneling in order to move the IPv6 data over an ipv4 Network which might be necessary even if the IPv6 data is traveling through an ipv4 Network all right so we've compared these let's talk about some of the improvements that ipv4 did not have that IPv6 does uh starting with some security and privacy measures if privacy extensions are enabled with IPv6 then we have something called an ephemeral address which is created and this is used as a temporary and random address that's used to communicate with external devices but the external device doesn't know the true address of the internal device and so this improves the the privacy and security for the user and this is what we call a privacy extension and it does have to be enabled some sort of a router point of view now another Improvement is a better composition of what we call the unicast address what this means is that IPv6 uses a unicast addressing structure to replace the classful addresses of ipv4 this offers a lot more flexibility and efficiency with addressing and depending on the category of the unicast address used there are different functions for each meaning that there are different types of addresses that are used and that way the computer automatically knows what the function is the first is called a global address which is sort of like the public or routable addresses uh in ipv4 if you recall most addresses could be routed those are what we call Global addresses we also have site local addresses which are essentially like the private addresses or non-routable addresses that are not routable to external networks if you recall these were for instance the 10.0.0.0 through 10.255.255 at 255 and then the 172.16-32 and then the 192.168 those are the private addresses well in IPv6 we call them site local addresses we also have something called link local addresses which are basically comparable to a pipa addresses in ipv4 and we're going to talk more about what those mean in just a little bit later but just to give you a little heads up and we have talked about it with uh uh a plus if you around for that this is automatic private IP addressing and we need because every device needs an automatic IP address if it's not given one by a server then it's going to give itself one what we call an apipa address and so in IPv6 these are called link local addresses finally there are IPv6 transitional addresses which are basically going to be used in the time being until we phase out of ipv4 these are used to Route IPv6 traffic across ipv4 networks through tunneling much like I've just described in the previous section now a mechanism uh built into IPv6 addresses is a field located in the IP header that's designed to guarantee network resources be allowed allocated to services that need time sensitive data such as voice over IP right we need that that is time sensitive because I'm talking and I want the person to hear almost as soon as I talk and so this time sensitive stuff is built into IPv6 one of the reasons that we use it now another improvement with this scheme IPv6 is called hierarchical addressing this eliminates the random allocation of addresses so connectivity devices such as top level routers are assigned a top level block of ivv6 addresses and then segments are added to those with blocks of addresses that are assigned at that level so basically it looks like a hierarchy from an IPv6 standpoint you remember we looked at an uh this sort of topology earlier now ibv6 scheme also has a much simplified header and it's going to make addressing a lot easier to read this improves the speed packet routing on an individual packet basis so obviously if we can simplify how information can get read it's going to simplify how routing can occur now data in transit is susceptible to a variety of things that could cause it to be delayed lost or damaged and these things can occur on the transmit side and quite commonly on the receiving side as well so the method the data is delivered makes a huge difference in whether the data is going to arrive at the destination correctively and efficiently so depending on the method of delivery there can be error detection which would mean we detect that there are errors and error correction which means we not only detect but we fix the errors when these recovery mechanisms are used now an important aspect of the data delivery begins with the actual connection itself so depending on the type of connection service used is going to give us an idea of what sort of delivery options are available so a connection in terms of networks is The Logical joining of two network devices through a specified medium that is established and maintained for a period of time during which the session exists in other words the connection is what allows data to be transferred between say my computer and a server computer now in networking and specifically in IP networks there will be connection services that attempt to provide data integrity and reliability now there are generally three types of connection services that we see when we discuss certain protocols and we've talked about these in some way shape or form but it doesn't hurt to sort of go over them in a little more specific detail first is an acknowledged connectionless service in these the connection isn't created however when data is received by the destination there is a acknowledgment of a receipt so website Communications use this type of service a great metaphor to think about this would be for instance a delivery receipt with regular mail so it's not certified we're not going to get a signature but what we do is we get a receipt that it has been delivered now with unacknowledged connectionless Services there's no acknowledgment sent unless the application itself does this this could also be considered Simplex Communications which we'll talk about in just a second so this is just like regular mail we send it we drop in the mail there is no acknowledgment okay acknowledged at least has uh and acknowledge that data has been sent but there is no connection made right there is no established session made between the receiver and the sender finally we have connection oriented services and by the way when we talked about these connection lesses we recall this is like UDP which is connectionless and IP here connection oriented we're looking at TCP now these are where error detection and correction are available as well as some flow controller packet sequencing in other words this would be like certified mail now there are also three types of connection modes that we're typically going to use they're Simplex half duplex and full duplex with Simplex this is one way communication only this is sort of similar to FM radio broadcast right you turn on your radio you tune in and you can receive but you cannot send data now we also have half duplex this is two-way communication but only one at a time this is like a pair of regular walkie-talkies only one device can transmit at any one time which is why we have to use those code words right over over over and out so this is like a walkie-talkie finally we have full duplex which is two-way and both ways simultaneously this is similar to the telephone in which we can talk and listen at the same time in some ways we have trouble understanding each other as a result of it now in networking devices are designed to receive and transmit data at different speeds and with different sizes of packets as well so certain devices are not going to be able to handle as much data as others at one point or another we talked about this briefly with mtus and MTU black holes so flow control is the managing of amounts of data and the rate at which the data is being transmitted emitted over a network connection flow control is necessary to help prevent devices from being overflowed with data some devices when there's too much data is received are going to potentially shut down to prevent certain attacks or simply are going to drop packets that are too large because they're going to cause delays on the other side of the scale if too little data is being received by the device it may just be sitting idly by waiting for the remaining packets in this case it's simply a matter of efficiency so there are two main types of flow control that are covered on the exam buffering and data windows buffering is a flow control technique where a portion of the memory either physical or logical via software is used to temporarily store data as it's being received in order to regulate the amount of data that's being processed buffering may be used to maintain data consistency as well as minimize overloading now Ram uses a type of buffer when data is being read from its cache right so remember we talked about RAM and that was what we called Cash now with buff bring there is a potential concern because what if the buffer becomes full well when receiving nodes buffer reaches a certain capacity it actually transmits a squelch signal I'm going to write that out just not only because it's a great word that says stops transmission or slow down your transmission so I can catch up now a commonplace we're going to see this type of flow controls when we're streaming movies you might have seen buffering when you're using movies for instance on YouTube or on Netflix or any of these sites the idea is if there's a problem with our communication we have a little buffer of data so that way we're not going to see a dip in quality of the film now another type of flow control is called Data windows the data window refers to the amount of data being sent and it can either be a fixed amount or it can vary and these are fixed length windows or sliding very sliding Windows rather if you think about the window and I put the data inside of it we can either have a window that is a specific length like this or a window that can't possibly get smaller based on the data and that's what fixed length and sliding windows are so to go a little more in depth into these with fixed length Windows the size of the packet of the data being sent is determined by the sender and the rate of transmission is determined by the receiver so the size is typically going to be pretty small and overall this is going to be fairly efficient the other thing to remember is that the packet size is always going to remain the same it's never going to change so if I need to send 10 packets they're all going to be exactly the same size or as much as I can draw them as such and so on and so forth now with a sliding window method it's a bit different the sender begins to transmit data typically with a small number of packets and with each transmission it uh waits for an acknowledgment or act packet receipt now with each receipt this contains the current maximum threshold that can be reached and then the transmitter is going to begin increasing the number of packets by a specified amount in other words it's going to start sliding that window from here over now it's going to continue to increase this over and over and over until we reach a maximum potential at this point we're going to start getting some congestion and so the receiver is going to send another act saying listen you need to slow down now and and this is a good rate this method is really going to allow for minimal data traffic congestion and a lot of throughput depending on the amount of traffic the size of the window can really vary dramatically and so this really gives us a lot more flexibility if you imagine if I have a home that has a whole bunch of irregular Windows I'm going to want sliding Windows now if I have a home with all these similar Windows everything built the same then I can use a fixed link window but this one's going to give me a lot more flexibility now error detection and correction is an important aspect of how we know our information arrives at the destination unhindered and unaltered one method achieves this by attaching supplemental information at the end of the footer that pertains to its contents and the receiving station is going to look at that data and compare it to the data it received the data matches it's going to consider it error free if not the data is going to be requested to be re-transmitted now when an additional Correctional component is added that allows the data to be rebuilt in the error in the event of an error this is going to become an edac or error detection and correction now parity check is a process where an extra bit is added to every word of data the receiving station can look for the bit on this word by word basis remember we're talking about words we're not talking about uh language we're talking about words as far as data goes and so it can look at these and therefore it can determine any errors that are built in because parity adds this extra bit to every word this method takes a little bit of overhead so it does ADD not only extra resources but some more data in there now with something called CRC or cyclic redundancy check a code is added to every block of data through a mathematical operation which is also referred to as hashing now this code is added to the end of the block and then it's transmitted when the receiving station applies this hashing method this mathematical operation to the code then it can should get the same data and if it doesn't then it knows there's a problem and it can request it to be resent like parity CRC is also going to add a certain amount of overhead because it takes data and calculation time all right so now just to review some of the topics we talked about we talked about the IPv6 addressing scheme specifically we talked to that it's a hexadecimal 128 bits divided into eight sections we also compared and contrasted IPv6 with ipv4 we saw that IPv6 for instance has ipsec built in and has a whole bunch of other improvements and mechanisms such as data delivery time sensitive and so on and so forth the important thing I really want you to know about IPv6 is that it does not require a subnet and we need to recall all of the truncation or readability rules which include removing leading zeros and combining successive sets of zeros but only once we also explained the different data delivery techniques and we defined a connection the different connection modes whether they're acknowledged connectionless simply unacknowledged connectionless or connection oriented we also looked at the different transmit types including Simplex which is one way half duplex which is like our walkie-talkie and full duplex which in effect doubles our bandwidth we also explained flow control buffering and data windows we use buffering a lot when we're talking about videos in data Windows remember we talked about the fixed and sliding windows finally we outlined error detection methods including parity which adds an extra bit to every word and CRC or cyclical redundancy check which uses hashing a mathematical operation so that we can ensure the data that was received was also the data that was sent [Music] welcome to module 6 lesson 4A IPv6 Concepts now we actually covered IPv6 earlier however as per usual some new ideas have been added to the syllabus so what I'll do here is I'll review some areas that you've already covered with Josh with my own take and then we'll go into the new stuff so IPv6 addressing address types new is a neighbor Discovery protocol which is part of IPv6 built in the eui 64 addressing is new tunneling types is new so ipv4 which is obviously the precursor to IPv6 it created a long time before we had home computers computers were pretty expensive and big probably the size of any room in your house so no um nobody foresaw that people would be using uh home computers just like when the telephone was created I think uh one of the first comments was why would I I don't need to phone anyone so uh there we go uh so it was just the scheme was designed just to cater for commercial Enterprises only so we didn't think we were going to run out lack of a simple Auto configuration mechanism so I eventually we had um DHCP was uh created which works well obviously it's got some drawbacks an ipv4 has no security built in again nobody realized that well there was no such thing as hackers obviously when IP was brought out because they hadn't been invented yet so nobody thought that we needed to have it built in ipv4 is hard to use with mobile devices especially when we're using the cellular Networks ipv4 needs massive writing tables required over the internet internet service providers have huge tables for routing all the IP traffic uh there's only around four million addresses available we actually ran out of ip4 addresses some time ago and around 50 of the traffic going over the internet at the moment is IPv6 which is why yeah we need to know about it so IPv6 uh there's that many addresses I don't even know what the numbering system is called for calling out that many but for every person alive there's many millions of available addresses now and that can be used with IPv6 and you'll read some documents about an app PT not really used and there's no need two and not because there's just no shortage of addresses really security is built into one of the fields in the IPv6 packet we have addressed Auto configuration which um is a major part of IPv6 and it's plug and play as well so things like when you enable IPv6 on an interface with most devices now it actually self-configures an IPv6 address we do not have broadcast and IPv6 we'll come to that later uh it's built to work plug and play with mobile devices again which is Handy so the address is there's several rfcs one of the main ones is 1884 if you want to read it it's a 128 bits each of these bits is divided into into eight groups of 16 bits and then each of those bits is separated by a colon which is a DOT on top of a dart HEX number it is used because it's just a lot easier to write out that many bits using hex and it is in um binary it would take forever the address is when you're typing them out on interfaces is not case sensitive so you could use caps lock or lowercase and the address will work fine and be accepted here is an example of an IPv6 and you can see if we just come over here so eight groups of 16 bits which you'll go into into a minute uh divided here by the colon and another 16 bit 16 16 16 16 and so on so if you wrote the address out in binary just for the I don't know why I should have said D here sorry Eed e e d e but if you change the hexadecimal here so this is the hex into the binary value it's one in the uh if I go one to I know you already know how um binary works for eight so one in the eight column one in the four one in the two so eight plus four uh it's twelve eight nine ten eleven twelve thirteen at fourteen so the E is number fourteen here uh 14 here in HEX now we've got the D so we've got uh one plus four plus eight so eight nine ten eleven twelve thirteen so D is 13. and then we're back to another 14. 16 bits two bytes in total so four bits uh four bits eight and then another eight 16 bits so that's two bytes we can compress the address so you can remove the leading zeros leading zeros are numbers that appear before and so this is a leading zero leading zero this is a trailing zero so we can't remove these because they've got numbers uh prior just before so if we get rid of the leading zeros for example here zero zero zero one becomes a one zero seven eight nine becomes seven eight nine and this is uh to save space and for when we're writing out the address is zero ABC becomes ABC and you can get rid of the trailing zeros here and just have one zero so this address is uh legal to write that out you could possibly have questions in the exam uh asking you to choose the correct compressed address you can use a double colon wants to represent consecutive zeros so here we go we've got all these consecutive zeros here for some reason well we've got rid of them just by having the double curl on here and we've got a double coal on here between the one two three four so what we've done is just compress all of these zeros and we've done it again here and then just to we could have put it in the second set of zeros but just to save space we've got rid of all these zeros here so practice this work out your own numbers because this is a typical exam type question main IPv6 address types Global unicast unique local link local and multicast you'll note we don't have broadcast that isn't a legal address and we also have any cast which I'm not sure if I mentioned here so the global unicast the this is allocated by the ISP and then you will get a mask Associated whatever the mask may be these are routable on the internet so you can send them out of your company and um they're legal they're legally recognized the numbers range from 2000 to 3 FFF in the first 16 bits current allocation there's there's trillions of these addresses so the current allocation has come in from 2001. this will this will last quite some time obviously there's a 48-bit provider prefix and if you uh check the images of the address packet you'll see the 48-bit uh there's a subnet ID you can submit inside the organization if you wish subnet to IPv6 is a topic but it's not in the CompTIA it is in the Cisco ctna and then the rest is the host portion of the address now I'm sure most equipment can actually do this but Cisco routers can self-generate this part here so what you would do is if you configure an interface you would you would basically configure whatever the address is dot b dot whatever whatever and then the host portion here the interface would um self-configure so um I've issued oh this is on my um Windows computer for the looks of it I've just issued an IP config or forward slash all and I've seen the IPv6 address that's been allocated here and I think Windows self-allocates these addresses also uh link local address the prefix for link local addresses are feat these are only valid between the link between two IB V6 interfaces so you've got an internal router and say for example an ethernet connection here then these addresses will be valid and these two IPv6 routers can communicate with one another using this link local address what it can't do is this address in here it can't be used to reach another device out here now if you've got another device the link local addresses of these two facing interfaces so for example fast ethernet here fast ethernet here they will communicate between one another here automatically created once IPv6 is enabled now these are used for writing protocol Communications IPv6 protocols mentioned in the syllabus but I don't think I've left it out for now because looking at all the official guides there's no um questions yet I will add it later on if um if that changes though traffic isn't forwarded off the local link certainly not using the link local address so here's a configuration for a Cisco router you I've enabled IPv6 routing I've gone to the faster ethernet interface all I've done is turned on IPv6 for this interface here the fast ethernet zero slash zero I've typed end and then it I've said show me this interface it's down I haven't connected it to anything but as we can see this address this link local address has been allocated self-allocated this is an important bit here FFF as we'll see in a minute but basically this is my IPv6 address I have an app to write it out manually at all I've already um shown you the windows one yeah unique local uh it's the IPv6 version of private IP addresses so you can use all of these on the inside of your network you wouldn't be able to Route them onto the internet don't think these are used anymore I think they're actually been depreciated if you get a question in the exam here it would be something like this what prefixes link local addresses are taken from fc00 uh forward slash seven for your subnet mask these depreciate site local addresses oh sorry so site local addresses that have been depreciated and overtaken by link local a unique local so you'd use this on the inside of your network if you want to do any internal routing what you couldn't do is use it out on your on the internet though multicast addresses are still used very much in IPv6 this is the prefix so write it down and put it into your studying crumb notes and multicast replaces address resolution protocol for IPv6 a use for duplicate address detection so when you first fire up your interface I'll talk about neighbor Discovery in a moment but I'll say just to save space I'll say this is the address obviously it would be the IPv6 address it will this interface will advertise out this address to um the network this multicast address saying I want to use this address X and if any of the any of these interfaces are using that address so this is using Y that's using Zed it will come back and say no you can't use that address but in this case my example here nobody's using it all routers must join the All host multicast group of ff02 and then whatever in the middle uh one so it'll all be zeros and then one and the all routers multicast group this is how enable Discovery protocol works so it must be allocated and listening to these two addresses and if I issue a show IPv6 interface fast ethernet 0 0 you can say you can see that it's joined these two groups appear the um the F2 and the F1 eui 64 addressing is the new part in the syllabus yeah so I've issued a show ipv IP interface sorry I've didn't do IPv6 because I want to see what the MAC address is because this is how eui 64 obtains the um eui 64 address so this is how or one of the ways you can self generate an interface it uses the MAC address the 48-bit MAC address obviously we need 128 bits 48 bits isn't enough to generate this address but what it does it takes the MAC address it inverts the seventh bit and adds FFF Fe in the center so right in the middle of the MAC address it's going to add fffe make sure you take a note of this for the exam so uh we've got zero zero one one hold cover white it doesn't say zero zero one one here and then here's the a here and then you can see the fffe has appeared he has inserted it and then it carries on with the rest of the MAC address BB c c d d so b b c c c m c d so this is how it pads out the address so there's two bits Mac address plus this but then it does this other bit here which is inverting the seventh bit so just to recap what I've already said we're looking at this part now zero zero one one well instead of that now we've got zero two one one all right so going into the seventh seventh most significant bit so this is our sample address here the first two nibbles uh or is one byte so this is 0.0 so a nibble if we have one two three four five six seven eight so eight bits is one byte which we've covered already oops one byte one byte eight bits but what we can do is kind of subdivide it in the middle here and we can have a nibble here and a nibble here all right so our first two nibbles one byte here is zero zero which would have all the binary bits basically pretty easy to work out so this here if you write it out with a nice uh font is zero zero zero zero zero zero zero zero so what we need to do is flip the seventh most significant bit so what we've done is one two three four five six seven eight so this is the seventh most significant bit and what we've done is gone all the way over here to find the seventh bit and we've flipped it so whatever it was here in binary we flipped it so one flip two sorry zero flip to be a one now if you wrote that out uh this part here you'd have um your zero would be covered two that's the one two four eight one two four eight Okay so we've uh enabled this column here and our zero has flipped to A2 and you can see here zero two one one and then um this is the MAC address we've got the fffe in the middle and then the rest of the MAC address this is how you work it out you might get a question on this so this is why I brought it to uh your attention and you just need to practice a few examples so what would this address be changed to if you write it down all right so I've just carried it over to the next slide here so Charlotte IPv6 interface we've got this address here and we end up with this global unicass address here and you can see already we've got the fffe created here so and because it's it might not show you another vendors but you can see here there's a clue it says eui so we know eui 64 is addressing well C2 in decimal is 192. or um in binary here one one zero zero double one double zero in hexadecimal is C and if you've just got a one in the uh two the two column here so one two four eight you can see uh that's a two see in hexadecimal is 12 so we've got 8 9 10 11 12. so I think we've covered hex earlier so you swap the seventh bit so one two three four five six seven this bit has to be swapped if we're doing the UI 64. and then it becomes a zero if you work this out zero zero zero zero the second part is uh C zero so here we go c0 and then it carries on as normal zero zero instead of C2 so I know it's a lot to get your head around just practice it watch this over a few times and then practice some of your own examples applying it enter your desired subnet and then add the command the tag eui 64. this is how you do it in Cisco you won't be asked about vendors or how to apply it I'm sure I'm just telling you how it works so I've added this address I want to say we're using um this subnet here this address and uh double colon so I don't care what goes there 64 and then I add the tag basically saying you um you allocate uh using the MAC address plus the seventh bit rule which will swap the seventh most significant bit from a zero to one or one to a zero and here's the command on an actual router so yeah you have to you can't just say create the entire address for the routable address um you have to add this tag here all right next is the neighbor Discovery protocol which is a major feature of uh of IPv6 this allows other routers on the link to be discovered there's a couple of messages you you need to be aware of which is RS router solicitation like are are any routers on the link this is the router solicitation message and it's sent out saying what what else is here the router advertisement is the reply you'll get from the routers IPv6 routers uh yep I'm here R A I'm here it just give us prefixes so whatever your prefix is on the network Etc these routers will say we're using this prefix and then this will be able to Auto allocate an address so it can communicate communicate on the subnet so this replaces our we don't have ARP working on the uh on IPv6 subnets also works to duplicate address detection which I've already mentioned the device the ipvx ibv6 device will say I want to use address X are any of you using it and then there'll be a reply if it is in use so there was solicitation asking for a neighbor's information their neighbor advertisement you advertise yourself out to Neighbors the solicitation asks for information about local routers these are the four types that you need to know about router advertisement advertise yourself as active these are the four types so make a note of them the idea I've already mentioned the neighbor advertisements are sent to check if your address is unique this is the address it's sent to which is the um save as a broadcast address but we're multi-cat we're multicasting in IPv6 no reply means your address is available to use the amount of air seconds should vary from vendor to vendor I haven't read the RFC actually but if you really wanted to you can read it so you can see the advertisement is going out with this address reply if you are this address using the icmpv6 packet um and then the advertisement here I am this address so basically you can't use it DHCP version 6 is used for IPv6 this is for auto allocation of addresses also used with uh it's used in conjunction with DNS for IPv6 and here's the RSC if you've got some spare time in your hands allocate IPv6 information to hose obviously the IPv6 is um the Gateway the the DNS server and another DHCP information host can request it with an outgoing router advertisement message allocated and requested using UDP bear that in mind because some people think it's TCP it's Port 546 and 547 the other subject you need to be aware of now is if you're running uh IPv6 on your network and then ipv4 nobody is going to come into work one day and have ipv4 taken off and only even in IPv6 you're going to have a transition period where you're running both of these protocols so what's going to happen is somehow IPv6 host reaches an ipv4 router and what you're going to have to do is tunnel the IPv6 information inside an ipv4 packet with a header and the trailer running ipv4 there's a few versions isotap uh 64 to the link dual stack is when you're running both at the same time there's a static to null I think yeah that's different to GRE you don't have to know the config so don't worry about it generic routing encapsulation has been around a long time but you can use that for tunnel in automatic as another type you can choose from if you want to study more I recommend everyone needs to do about uh four hours studying to IPv6 this is for interviews technical jobs uh technical interviews and just to do your day-to-day job you do need to understand it there's a course on them cartoon network.com it's 16 hours in total but I broke it down into I think the beginner course is about three there's an intermediate with loads of routing and then maybe I think five or I'm trying to do my math now six to 12. seven hours extra which is Advanced so you could just do one part and then when you come to do something a bit more difficult do the second part and if you want the third but um you really do need to know IPv6 I've been talking about this for about four years now and it's becoming more and more urgent so you I used to recommend it and now basically the the level of uh understanding in the the level of adoption is basically you you have to know it it's just like not knowing ipv4 now if you go into it um if you go into an interview so please do learn it and we've covered IPv6 address types Navy Discovery eui 64 and then tunnel in that's all for now thanks for listening [Music] thank you Network routing and IP addressing IP assigning and addressing methods so having discussed both ipv4 and IPv6 and the difference between these different types of IP addresses we now want to talk specifically and in more depth about how IP addresses are assigned to a specific node or client or server so in this module we're going to look at the two different ways that IP addresses are assigned this involves defining the first static IP addressing static meaning that the IP address is always the same and dynamic IP addressing which means that the IP address can change we also want to talk about the strengths and weaknesses of each of these addressing methods and we want to compare the features of one and the other we're also going to identify when we want to use Dynamic IP addressing as opposed to static IP addressing and Define when we're talking about Dynamic IP addressing the terms DHCP the server and protocol that are responsible for allowing Dynamic IP addressing to work something called the scope which lets the DHCP server know which IP addresses are up for grabs and then the lease which just like the lease on an apartment lets the both the server and the client know when a IP address can be used and for how long we also want to talk about when static IP addressing would be preferred and as you can probably tell from the way this is worded we generally want to use Dynamic IP addressing as we'll talk about but there are certain instances in which a static IP addressing is the best method for us and we'll talk about those as well so first let's talk about static IP addressing it's done manually and that's what this really means static means manual assignment which means that I literally have to go to the computer and type in what the IP address is and how I want to use it so there are two major flaws with this first it can be very time consuming because it has to be done manually and each address has to be entered individually by hand in addition this takes a lot of time and it's prone to a lot of Errors human error is often a factor when we're configuring addresses for a large amount of systems and if you can imagine I'm working in a system of say 5 000 computers then I'm going to be typing in IP addresses a lot now while this may be a worthwhile method when assigning a very small amount of addresses it's obviously not very practical when I'm talking about large quantities and the other major flaw is that it has to be reconfigured every time the address sync scheme changes so for instance if I was going from ipv4 to IPv6 on my internal Network I'm going to have to re-change everything once I've switched over or let's say I want to change my naming system maybe I want to go from a Class C to a class AIP addressing system if I'm an ipv4 and in this case I would have to then reconfigure everything on each computer and you can imagine the amount of time that that's going to take so due to its many flaws we're really not going to use this method static IP addressing which means again manual assignment the way you can remember that is that static does not change right it remains constants and the word static meaning not changing is what tells us that so we're only going to use that in specific instances and I'll talk about that a little bit later so as a result it's very rarely used except in very specific instances I'm guessing you've never had to enter the IAP address on your Soho router or at your computers at home and that's because we're going to use this other method being Dynamic addressing now as the name Dynamic implies the IP address can change which means that it is automatically assigned now this is a lot more useful of the of the two that we have for many reasons it's done automatically through a protocol called Dynamic host configuration protocol or DHCP so you ever hear DHCP that is what is referred to when we're talking about Dynamic IP addressing this is part of the tcpip suite and it allows a central system to provide IP addresses to client systems now since it's done automatically there's no possibility of human error and it's also a lot more efficient than static IP addressing as a result it's a lot more common of a method uh it also eliminates the need to reconfigure a system if the addressing scheme is changed so it's far more commonly used because of all these reasons like we just said it's more practical and more efficient because I don't have to change every computer all I have to do is tell the DHCP service computer we'll talk about that in a second that we're changing everything and all the underling computers automatically are going to change so if we move over real quickly into our Windows system and let's go into our Network properties and we'll go ahead and go to change adapter settings I'm going to right click on this and go to properties now we'll see over here if I click on tcpi P4 and go to properties it says obtain an IP address automatically so through DHCP the IP address is being automatically obtained just like DNS is also going to be given out automatically now if I wanted to do it statically I would have to manually assign an IP address a subnet mask and a default gateway for each device so you can see where we're not going to want to do that so let's talk a little bit more about DHCP or the dynamic host configuration protocol this is the protocol which assigns IP addresses and it does this first by assigning what's called or defining rather What's called the scope the scope or the ranges of all of the available IP address on the system that's running the DHCP service and what this does is it takes one of the IP addresses from this scope and assigns it to a computer or a client so for instance let's say that we're dealing for simplicity's sake with a uh 192.168 Class C Network so the scope might be something like 192.168 dots one dot 10 through 254. this means that of the IP addresses it's going to assign it's not going to take anything in front of the 10. so this gives us dot 1 through dot 9 to use for static IP addressing so what this ensures is that the DHCP server is not going to assign an IP address that we have already manually or statically assigned to another device we'll talk about why we would want to do that in a minute but this ensures again that the scope uh that the DHCP is not going to assign an IP address outside of its scope then what it does it takes this available address and assigned it to the client for a set amount of time and this is called a lease so the lease says how long the IP address is going to last now the reason that we had leases is because remember if I turn off my computer it no longer needs an IP address it also means that let's say I'm taking a computer away I don't if I have a if it has a lease of forever then that computer now has one of my available IP addresses so sometimes we'll have an IP address with a 24-hour lease or maybe a two day lease but whatever that lease is at the end of that lease it's going to have to re-again ask for another IP address this is also the way that we can share a limited number of IP addresses with a lot of uh computers or nodes so when we had the internet we used to dial up to the to our ISP or Internet service provider what this would allow is it allowed our uh ISP to provide us with one IP address that only lasted for a certain amount of time and then when we disconnected the IP address or disconnected from the server and therefore didn't need the IP address it could assign it to someone else and it didn't have to worry about us coming back on and wanting to use the same IP address because remember one of the rules is you cannot have two devices with one IP address all right now let's talk about how this works from the client's point of view basically what happens is I have a DHCP server here and it has what's called a trusted connection to the switch we'll defined what a switch is previously and we'll talk a bit more about them later as well but it has a trusted connection this computer say comes online and says hi can I join your network can I get an IP address it sends its request through what's called an untrusted connection to wherever the DHCP server is now the DHCP server at some point finds this because this is generally a broadcast because again it's not a unicast it's a broadcast because this computer coming on doesn't know where the DHCP server is so it sends a broadcast message out the DHC per P server then responds and offers a lease on an IP address at which point this untrusted or unassigned connection becomes a trusted one now when the lease goes out it's again untrusted and so it needs to repeat the entire process again now so far we've been pretty fair to DHCP and expanded on the benefits for dynamic addressing but there are some exceptions when a network is configured uh for DHCP and we don't want every single device to be automatically assigned an IP address for instance um the DHCP server itself needs to have a static IP address this is because we don't want the DHCP server to be changing addresses and what's going to happen is if we have a lease theoretically the DHCP server could change its IP address and since every computer on the network needs to know where to go that's going to have to remain the same this is going to go the same with the domain name server so the DNS server which allows us to convert between say google.com and the IP address so we don't want to have to find this every single time and we have to set it as something specific meaning static we're also going to put our web server as some static IP address this is the reason why if you wanted to get an account with your ISP or internet service provider and you wanted to run and web server from your computer at home you would need to ask for a static IP address be because that's the only way that someone can link through DNS to your web server and so our web servers always has to be static because when I type in google.com I always wanted to go to one of a few different IP addresses finally printers are something else that we want to have the printer we don't want to move around we want to be able to lock it in when we install it on the computer same with any servers also routers the Gateway computer or the Gateway device that allows us to get out to the network we need that to remain the same so that's why when we Define the scope and in previous example we defined it as any IP address between 10 and 254. we don't want it to change because we want these nine IP addresses to be ones that we can assign now sometimes we're going to make this a little larger so that way we can assign a lot more static IP addresses so also maybe a wireless access point we might want to be static etc etc and all of this again is done through a web interface or through some sort of router device or through a terminal or something so this is not something we're physically hard wiring onto the device because again that's that's a MAC address a physical address but this is something that we want to set through a software of some sort all right so just to recap what we talked about we defined static IP addressing again static means that the IP address does not change it also means that it had to have been manually assigned okay now we also talked about Dynamic IP addressing which DHCP allows us to do and this means that the IP address can change because it is automatically assigned one thing I didn't specifically talk about what we referenced in previous modules too is that a pipa address that automatically assigned IP address which if the dynamic IP address system is not working so the DHCP server for instance is down and it can't get an IP address from the DHCP server it's going to assign itself its own IP address if you remember that was 169 about 254 dot x dot X so if you see this is your IP address then guess what your DHCP server is down we also identify the strengths and weaknesses of each of these so um we Define the static we Define dynamic and then we identify the strengths and weaknesses of each remember the strength of dynamic is that it's easy and it requires less work if we change anything of course the Dynamics or the the downside of it could be this apipa or we don't want um the IP address to change we also talked about when to use Dynamic IP addressing which is in most cases we Define DHCP which allows a dynamic IP addressing to work scope which is basically the range of IP addresses and the lease which is how long the IP address is going to be sent out for and then we recognize when static IP addressing is preferred for instance when we're dealing with printers or routers or even the DHCP server itself which we cannot have change [Music] welcome to module 6 lessons lesson 6 DNS the name naming system covered up we're going to cover a lot of stuff in this presentation but I'll try and get through as quickly as I can what uh we need to know what DNS is what our domains the fully qualified domain name the DNS root servers so what happens or how does the system actually how do we interrogate it and how does it update itself what are DNS records as well this is stuff that's actually in the syllabus now I'm sure you've already heard of domain name system or DNS you can see in the um output here the image we've got.com dot org.us there's actually loads and they're added um quite rapidly and as each country has um appealed for their own top level domain more and more have been added so there's lots of countries now that you can register domain names for some of them are protected for example um if we go to.com dot a u for Australia you actually have to have a business uh number so even if you live in Australia you must have um it's called an ABN Australian business number so not you can't just have anyone having a DOT com.eu other countries have got restrictions some haven't so it just depends on where you are so it's the name of a computer it's got a an IP address on the internet now these can actually be shared you can have some of the same domain names if you buy cheap hosting and they'll all be sitting on the same IP address but this DNS can deal with this so yep that's just what I've said if you uh for example I used to host of these but not anymore uh what was it called HostGator I'm not recommending these by the way you could have this guy's website somebody else's another person another person but they're all sharing the same IP address but that's easily taken care of so what is it it resolves the names associated with a server to its IP address so you can see on my home computer here I issued a ping cisco.com well this a URL is sitting on a server somewhere and probably on spread among quite a few servers actually but somewhere from my home wherever I am I've got to get through to my ISP and then obviously we've got a whole bunch of other hosting companies wherever they may be and then finally we get to the building hmm that Cisco owned maybe Paulo Alto or somewhere else but there has to be a result between this and what actually comes back because tcpip doesn't ping names it pings uh IP addresses so 172 163 4.161 that could have changed but something has to happen before the icmp packet can be built and as you know from other lectures he's got to have uh inside their Source destination and their data whatever else inside the packet so DNS will take care of the uh resolve for us when we tried to access a samplecompany.com from the web browser DNS translates the domain name into an IP address so I've just put an IP address if you're super super smart and got a great memory you could basically browse the entire internet just using IP addresses however if it's something new for example if you want to go to xyzsite.com you're not going to know obviously the IP address and this can change over time by the way they can move to another company and assimilate with someone else or buy them out so that IP address is used by our computer to communicate with the corresponding server on the network as a database DLS knows about the relationship between the domain name and its IP address it's a distributed databases spread across the world I'll come up to this morning here but um you've got your ISP which will probably have several thousand of the most common DNS addresses and and mappings in there if there isn't one there then when you do your search at home if it's not there then quite quickly it will be forwarded to like possibly it might not be the um one of the root servers which I'll come to but it might be an authoritative DNS server that will hopefully resolve if not then it can carry on it uses UDP Port 53 just uh bear that in mind because you could come up in the exam uh just people argue that it DNS doesn't use UDP it does for our for our purposes DNS uses UDP now if you happen to be working for an internet service provider then um TCP is used but it's used for Zone transfer so all the domain names that um will be transferred across that obviously has to be done reliably or large requests it can also be used if there's multiple this depends how you've got it all set up if there's multiple failures looking for xyz.com then it could also move to TCP this is because it could be caused by a UDP dropouts or fragmentation but we probably wouldn't need to worry about that for our day-to-day jobs our DNS database or the DNS database divided into sections called zones these store name information about one or more domains and the domain is included in the zone The Zone becomes an authoritative source of information about that domain so as I've already said we need our routers and multiles which is we we concerned about IP addresses to make forwarding decisions so we had to have this service created uh you we know this stuff already difficult to remember kind of alluded to it so the IP address with the domain system we don't need to go through the headache of remembering the IP addresses a little flogging the flogging the point a bit here so the DNS name system is based upon the domain name space collection of unique names that denote other kinds of information such as the IP address now there has to be certain rules in place obviously and these rules have been added to and amended if you if you've got the time and the inclination to read through the rfcs and certainly when we come to see Name Records conical names I'm not saying that twice they had to issue an update on the RFC because people were getting a bit confused about what it what it did and this is one of the things about when you when you create something and you write the rules of the documentation you you presume people already understand stuff because it's in your head this is why it's handy to get other people to write the documentation and then you read it and I'm saying that because documentation is included in the network plus the exam so the namespace is a hierarchically there's too many long words today structured and has rules to uh that let the namespace be divided into subsets so in the land uh the domain is a sub Network consisting of a group of clients and servers I'm not talking about the um your internal um intranet for example I'm just talking about the day-to-day lands of IP addresses you could have the intranet or obviously um Microsoft also has a naming system the active directory so we're not talking about that so Internet domain is a descriptor of The Logical grouping of names and it indicates whether the names belong to the following commercial entities and non-non-profits I'm not sure what the non-profit is.org isn't it which isn't isn't really the case because um I've got a DOT org website so it's not protected you don't have to be a registered uh charity educational is dot uh Ed I don't think it's dot EU it's dot e d u now I you can't get these as far as I know certainly not for USA you have to be um a uni College something like that so I presume you have to have some sort of documentation or number government agencies.gov and so on you can subdivide the domain into groups called subdomain so the DNS domain can also contain hosts these refer to computers and services so we've got an example here training.samplecompany.com so this is the first obviously the top top level domain which we talk about then somebody's registered this but then when you go into your admin panel you can add these sub domains here for example my I think it's called rack start how to network.com I've got the same sort of thing I created this subdomain which has got its own IP address at howtonnetwork.com is sitting somewhere um actually know where it is it's sitting on a server say say no I IO the the um racks are sitting somewhere else because I've used DNS records that sit in in um oh I actually remember where it is up at Nevada just so you get the point anyway so samplecomedy.com the.com is known as the TLD top level domain okay so you could be asked this in the exam this is ISA the fqdn the fully qualified domain name is a complete domain name for a specific computer or host so it's got the host name and the domain name so for the fqdn for a hypothetical main mail server might be mail one and you probably have this if you're in a reasonably sized company that's got a dedicated Mouse server so you're handling all your mail most of these services are named you know mail one mail two whatever and then your company name so you're managing all of your um incoming and outgoing mail which is probably um a good idea so you can Blacklist and and comply with other legal requirements so mail one is a host obviously you can use more than one server you can use virtualization whatever you want but um hypothetically speaking it's a a server dot com is the TRD as we mentioned so DNS root servers these are the contain the top level domain registry that maintain the global domains so at some point if you register a brand new domain name you'd register it with your um it could be with your hosting company I'll just put HC and then that eventually will get forwarded to the um the TLD and then that will be forwarded to non-root service So eventually your ISP will probably get a copy so as of first of August 2018 root server consists of 933 instances these are operated by 12 independent route servers if you're interested in more information you can go to root service.org and have a read up and they've got some maps on there of where all these root servers are some examples of globaldomainsr.com or netgov.edu country codes US Canada CN oh I don't know Denmark France Japan CN oh that's going to annoy me now I'll have to look when I finish this presentation if he comes to me I'll say uh you wouldn't be tested on that by the way uh DNS root servers also known as root name servers if anyone says that to you it's perfectly um fine for them to say that and it describes where the authoritative did a service for the T top level domains are located please give answers for specified set of zones from its own source so it doesn't have anywhere else to go if there isn't a response something's gone wrong or the domain doesn't exist at the moment and you'll you'll get some sort of timeout message on your web browser non-authoritative servers these provide cash dancers or Cash Aid I know some people say that are obtained from another name server so as I said you've got the uh the root servers here and then other companies large organizations just to save traffic and time can query these and then if they so wish they could also be queried by other servers and so on and so on and so on the DNS is composed of a namespace this is distributed database it contains the data that includes the host names if you recognize the structure there it's similar to a file system in Unix the name server translates the domain name to its corresponding IP address and we've seen an example of that does the response to the DNS query it receives from resolvers or the name servers I'm going to talk about um to our resolvers in a minute I think I'm not sure which slide it is so the answers to the DNS queries are based upon the contents of the name server database so obviously the database is full of records of um mappings so um x.com and it will be mapped to there's a lot more than this but as a simplified illustration cached information is learned by the name server from other name servers how often they update the cache uh just depends on obviously their local configurations now you can get an authoritative answer this is based on the contents of the name server database if it's a cached answer it's known as non-authoritative now on your PC you can issue ip config and this has worked for me before and forward slash flush DNS say I've moved my my website from one hosting company which I have done in the past to another I can um I can force a flush to find out where to to see if this um it's been moved correctly and obviously I could put the IP address in but this is quite a stressful time if you own a business because you've got your website um technically in two places although this is the old version and eventually the records will update but uh could possibly be asked in the exam ipconfig uh forward slash flush DNS and try it at home if you like what's the DNS composed of as resolvo is the next part which I mentioned it's a software component that comes bundled with your operating system also in network Hardware the internet applications such as web browsers and email clients need a domain name lookup so this is a piece of software that um issues the DNS request the resolver accepts the DNS queries and if the required information is available in the local cache it returns that data to the client so your PC will use the resolver a piece of little piece of software somewhere then it will go out to the internet and obviously return it so then you can issue the ping which we already saw and it's not available it sends the query to the name server when the resolver resumes the name server's response it hands the result to the application that initiated the request so this will be your web browser email um email package whatever you've already in obviously most of us are in our email off the cloud now like um Gmail so internet application sends a query for translating the sampler company resolver checks the local cash so you you could actually check your DNS cache on your home computer if it's not available then it hands over to the result the resolver hands it over to the nearest name server which would be normally your ISP name serversy determines whether it can provide the data if it's not available then it goes all the way off so PC resolver which basically just checks your your DNS cash on your home computer if not it'll go off to your ISP if the ISP doesn't know it could query another server but let's just say it goes off to the the air route there so this would all happen pretty quickly obviously you've you know yourself you've put in a URL and just sat there in how we're so impatient nowadays you sat there in any more than five seconds you start hitting the refresh button all right so the name server ask the.com name server and gets finally gets the IP address since the sample company has the IP address in its own database uh this this would be for a new domain I guess the name server that requested the IP address now gets an authoritative IP address as the answer and that's all finally relayed you could have a couple of query types a query received by the name server this is a recursive query this is received by the uh received from the resolver non-recursive is received by other servers so they could just be doing an update of their own records uh probably in the exam you'll be asked a little bit about what are DNS records what do they consist of also known as resource records these have the information that we need to do the resolving the records map a domain to its ipv4 address these are a records so this is the type of question you might get asked what has an a record it maps The Domain to its high people for address so here's an example you would put these in when you register your domain name if you host with the same company that you register so there's a company called one two three reg dot Co dot UK that I used to register my names with and host so I think it was all done for me there now some of these domain names um say in 60 days.com I um had it registered here but it's actually hosted somewhere else now so about to go in and um I actually put the name server that's the only part I've put in but there's a there's other records I can manipulate and as the owner of this domain I can do that but just be very careful what you do if you don't know what you're doing then you need to ask for help because things can go wrong because as I've told you you can split your mail to go to oneip address your um your web server can be hosted on another IP address you've got to have records for all of this so example of an a record first is used to take care of situations when someone tries to access the domain name without typing www most of us don't bother now so it'll resolved correctly the the first one being they say ah sorry so somebody hasn't put www and this is um this is a wild card so anything before your domain name is just going to go to and whatever server they're hosting it on here the second record we saw is the wild card it will direct any subdomains to the hosting server if you so wish you can then point it off somewhere else or you can add it into the DNA DNS records the quadrupalade if there's any quick way of saying this actually AAA oh could you play because um over in Australia this means the Australian um Automobile Association I know it's Triple A we've got over here so you're just gonna be careful what if anyone else is using these uh letters this is an IPv6 address that maps The Domain to its IPv6 address obvious obviously because um we need to be we're moving to IPv6 now so the 128-bit address there's an MX record which you probably won't be touching unless you're doing your own mail stuff to Maps the domain name to an email server if you're working for a big company they'll take care of that but looking at the MX record we could identify the mail server to which the emails are sent uh C name conical name record used to specify a domain name or subdomain as an alias of another domain so it allows the mapping of a domain to another domain so for example um you complete subdomains such as the mail or your FTP to your main address and you can do you could do this to make your company look bigger and I think my FTP certainly just points to my my normal server yeah but obviously when you're doing FTP you need to specify um in your software that you're using FTP so this that was that's how it would work so there must be an a record for the hosting server before aliases can be added so cname aliases must point to another domain so if somebody types um bar.example.com there's a cname record that basically says that is actually on um the C name is food.example.com then the the search takes place the DNS search takes place for food.example.com there's an a record so IP B4 record and it's saying yeah this is posted on this particular server PTR records pointers Maps like pv4 address to a clinical name for the purposes of the reverse DNS lookup so this is uh the reverse so normally we do um xyz.com and that goes to but the reverse can happen somebody could type 192.1.1.1 when you type that in your browser I think you um I need to test that actually it won't stay so if you if you type that you may well see it actually resolves to this might depend on your browser software SOA State start of authority record it's the first record in the zone file it declares it contains the most authoritative information for the zone information is the email address of the administrator you normally have to put something in unless you want it to be private the name of the primary DNS server there's a serial number time Fields when it was all registered and on their last updates uh two of the types of Records static is when it's done manually here and dynamic it's automatically updated there's two types of Records and Dynamic DNS this is a process of automatically um updating a Dynamic DNS record in the name server what can happen is this is all almost in real time could well be used if you're using cloud computing and your setting up servers tearing down servers moving information Dynamic DNS will update the lap information and the um names so useful when the IP addresses of our devices keep changing uh whenever a client computer using DHCP gets a new IP address it can use Dynamic DNS all right so we covered a lot of stuff you know the core stuff about root servers and AE records and quadruple a records I think that's the type of stuff that has questions on DNS domains fully quite fully qualified domains root servers records a lot of information and thanks for watching [Music] thank you welcome to module 6 lesson 7 proxy servers objectives we're looking at what a proxy server is an introduction uh the uses of proxy servers and forward proxy servers reverse proxy servers so you may have actually heard of these before especially if you've worked in an office whereby instead of connecting directly out to the internet your settings will be searched that you'll connect to a proxy server especially um for getting out to surfing websites the proxy server will do a few things which we'll look at in a bit so it's in a mediator or an intermediary between you and some other service you've got the client computer the destination server and then obviously the proxy in the middle here's an illustration here which we'll talk about the caching and web filter in so it's mainly uh used for uh surfing when you want to go out and surf the web for whatever reason it can then filter what sites you can and can't connect to it's um caches some of the content so it's got a copy of regularly visited our websites to speed up the um the surfing experience for you makes requests on behalf of the client computer so you're sending the request out to you to what you think is the internet but it's going to the proxy and then the proxy design your behalf the proxy receives a response from whichever server say the web server on the internet and then sends that information back to you so it intercepts the communication between the client's computer and the destination server I've already mentioned that you don't actually directly connect to the destination you can have different proxy servers to serve different traffic needs you might have a proxy server to handle only HTTP and then if you're doing FTP then it may handle those requests and on a different server what does it do it increases performance so um it's mainly due to caching or you may have quite a powerful proxy server that's done doing all these requests for you increases security because what the outside servers on the web see is the connection coming from the proxy are not actually and the uh the client device or the host device it also as I said caches content so it can serve up and saved copies of a website it could be a News website or something else that may not um be updated too regularly and then whatever these rules are on that proxy server it will refresh that content at given intervals so you've got to be careful sometimes you can actually be served up a cache of a web page and the actual live website has changed so it's something to bear in mind when you're configuring this on your network if you do it crazy security as well filters our unwanted web traffic malicious files before sending that onto the end client if the client tries to download a malicious file unknowingly the proxy server can filter it out and you can have a firewall in between your proxy server and a client or between the proxy server and the internet or both depending on what your requirements are so already covered that actually a forward proxy server is a new thing on this syllabus it acts on behalf of a client computer it gets the requested information from different servers servers on the Internet only interact with the proxy server and they don't know about the client's existence which is the concept we've already been discussing now there's something um known as a reverse proxy server and the clues in the title I suppose it acts on behalf of the servers on the inside of an organization but you can see here some host on the Internet is trying to access your web server internally and the proxy server will act as the intermediary deciding what does and doesn't go out and also obviously it will could have cached copies of what's actually on the web server the actual web server on the inside so um since the service is behind the proxy server the following is true the client is not aware of the services existence this is the internet client wherever that may be and it treats a proxy server as the origin foreign it can also be used to balance the load under server farm so it can pull different servers at the same time or load balance now the servers are considered to be on the server side of the internet because of the following The Intercept all the traffic coming from the internet they make it more difficult for hackers not impossible but more difficult to get to get the details of the internal Network all right so in brief we've covered proxies and introduction the uses of them forward proxy servers and reverse proxy servers all right that's all for now thanks for watching [Music] welcome to the lesson on network address translation on Nat for short and a look at what it is ipv4 addresses IPv6 addresses benefit of having NASA using it Source Network address translation destination that and port address translation or also called Pat or Nat overload so what is in that it basically translates in private IP addresses into public IP for addresses the private IP for addresses um RFC 1918 I think it is these provide addresses that you can use internally on your network but they can't be routed over the Internet so all of a sudden you've got a problem so this helped solve the issue of running out of ipv4 addresses however then we have to resolve the issue of not being able to wrote route those addresses so and that is a router function actually these routers and firewalls can do nothing so normally it's enabled at the boundary where your local area network meets your internet connection you don't need to bother not in usually internally on your network no particular reason and we use Nat with ipv4 addresses ipv4 has approximately 4.3 billion unfortunately the DraStic growth of the internet due to affordability of and and user equipment basically I mean maybe we were running out of ipv4 addresses so Nat was a temporary solution to a permanent problem IPv6 is the replacement obviously for ipv version 4. now this is the long-term solution there is a version of nat available for IPv6 I don't even think Cisco included on the syllabus anymore the reason is there's an almost inexhaustible number of available IP version 6 addresses um I think something like Millions per every per every person in the world so it's pretty much inconceivable that we're going to be running out of them anytime soon certainly within our lifetimes anyway so it benefits as well as using it so we don't really have addresses it actually hides our internal addresses on our private network from the internet which is pretty handy so it's a security feature these are the private addresses which hopefully you're already familiar with you need to know this range of addresses because this is a favorite exam topic for comtier and also Cisco and Microsoft these addresses you can arbitrarily inside them with the dhp server inside your network or um yeah you'll have DHCP server somewhere usually I wouldn't let any users assign their own IP addresses so let's say we have a lan with computers that assign these private IP addresses and internally we've got a PC one the data back it goes to our router the router will Nat to this address for a routable address which you've added to the configuration somewhere and it's one of the addresses you've been allocated the packet goes out to the internet somewhere comes back your router will have a table and that translation table and it will recall which address on is on the inside which is on the outside and then um re-nut it so it populates the packets for the correct header and then forwards it back to the um PC on the inside of your LAN so in this case this is in Long longer version of what I've said really this case the hudternetwork.com so if I have the server on the right there a scene that it's coming from a routable IP address it just wouldn't get routed by your um ISP otherwise you can tunnel addresses but you still need to Tunnel them inside a routable packet Source Network address translation a bit of a strange term this but comps here are coining it basically it means the um Source on the inside of your network is being nattted out to a routable address so you're initiating the connection from your source so you've got a 192 Network and it's been translated to a range of addresses on this router probably not a good idea to have one routable address because you can only ever have uh one connection live from the inside to the outside so I've covered that and since the source private IP address is replaced with an external public address it's called sourcenat to be honest I've only heard um the term that's used in all my years on networking but you need to be familiar with this because they've put it in the syllabus for some reason okay so I've covered this the other thing is destination Nat this is where the connection has been initiated from outside the network and say you've got some sort of internal um web server that serves members of the public who want to find out more about your company you normally have this off a DMZ on a router interface also or a firewall somewhere so this time the packet has come from and the in the internet and it's hitting your router and your router has a map in so this will be a permanently permanently featured address um a mapping inside your router or firewall now if you look at this image it's probably would make more sense just to have a routable address anyway on the inside of your um Network somewhere in the DMZ the demilitarized zone which is a safe zone for external hosts to access that isn't on the same interface as your local area network that would probably be a better idea but otherwise this destination that is an option here so I've mentioned dmz's uh through our public facing server Although our public facing server has an internal IP address the users on the internet obviously cannot connect to it which we've already covered so dnat to destination that is the solution there you can use destination app for load balancing um the traffic coming to servers from the internet so you could have three servers low balancing um lots of web connections coming in and there's different types of device you can actually use for this um and so it's all getting load balanced to one routerable IP address but then two three four or more and non-routable addresses on the inside of your network so when the user sends a packet it changes the destination public IP address and to one of the internal private IP addresses the last thing is Pat which is actually used more often than that port address translation normally when you have a small company you'll be allocated a single IP address but you still want to do nothing so what this does is it uses your oneop address but uses port numbers after the IP address for source and destination so this is the this is the solution normally um for this solution here you'd have a static IP address in one to one but you can't afford that for whatever reason so you've just got one IP address externally but several hosts on the inside so what we have is a port number for example 192 168 1.3 and then a port number your connection would go out on a specific port number for example Port 80 if you were doing a web connection but it would come back in and then get changed to a a random port number or you can configure a range of usable port numbers that are outside the well-known port numbers of m0 to 10 23 I think it is when the internal host of the private IP address initiates the session it will generate a TCP or UDP port and that's just unique to that session so you can see here internally we've got Port 15345 externally two zero two zero one to be honest it would normally be a well-known port number such as a FTP DNS or web traffic yeah this port um mapping is kept on a table inside the router it does expire after a while just to clear the table but normally um more than enough time for you to complete all of your sessions but that end table expiration time can be altered on the router all right so now at ipv4 IPv6 which is a solution to address to depletion but we don't really use that much at all with IPv6 some of the advantages remember security and also you get to use lots of addresses on the inside of your network and and up and and one address or more on the outside of your network all right so that's all for now thanks for watching [Music] tcpip tcpip simple services in the previous module and lesson we discussed the way that IP addresses are assigned now in this next lesson we're going to be talking more about the tcpip suite and specifically in this module I want to discuss some of the simple services that are in the tcpip suite what they do and what some of the output might look like for some of the services and why we might not see output for some of the other services now you might see this on the exam and you might not but either way it's a good thing to know about and just in case now first we're going to talk about all of these different simple tcpip services and in some cases we're going to demonstrate them and just to give you an overview of what these are these are cargen or charge in or character generation the daytime service the discard service the echo service and quote of the day service now some of these happen in the background are sort of embedded into other protocols and services that we might have seen but these are important again to know about in a sort of General way so the five uh simple tcpip services are listed here along with the description of what it is they do cargan or character generation or charge n or whatever the uh preferred way that you want to pronounce it is is essentially what you get anytime you choose the option send test page to a printer it's made up of ASCII characters and ASCII again stands for the American Standard code for information interchange so this is usually used as a debugging tool when you're uh creating or troubleshooting printers or print test pages and so what it does it literally just generates characters and we'll look at this in a little bit the next one is the daytime service that ATM service is usually used for checking errors or changes that happen within a system's internal clock it presents a message with the exact time that a change was made or an error occurred and we'll look at this format in just a minute but basically what's important here is that the output from this can be used for for instance the Event Viewer sort of what provides information to that and if we're going to see it in a um text based mode you will see exactly what that's going to present in the next slide now the discard service so we've talked about character generator and daytime the discard service is basically used for messages and information that are not important and therefore should be disposed of it discards these messages automatically when they enter this port or the port that discard is working off of this can be useful when you're configuring a system and using test messages that you don't want necessarily to display so note that because the messages are immediately discarded there's really no response message that's issued and therefore I can't show you an example of one but just realize that discard is going to usually be used for network setup and configuration and is going to make sure there is no response or acknowledgment now echo or the echo service sends an exact copy or an echo hence the name of any message that enters its port to a place in the system where the message can be monitored so this is often useful for when you're monitoring things that are going on in a network because the echo service simply Echoes and copies and forwards any messages it receives there's really no way to show what an example would look like because they each look very different from each other but basically in many cases we're going to get some sort of message that happens internally and we want the computer to tell us that message once again so we can see what's going on internally and that's when we're going to use the echo service finally the quote or the quote of the day service sends a short message that's been selected by the administrator of the system to a client's device now this service is used primarily for checking the connection to client devices so it's really similar to like Echo the content of the message is not this is not what's important what's important is that it is sending something and that way we can make sure that the service is working and that the um troubleshooting is sort of easily solved now as it mentions here it can be taken from a specific file right in here which is where random quotes can be taken of if you remember or if you know the hosts file it is also located in this folder so let's take a look at this character generator uh and some output that it might give you now this is what a test code page would look like these characters are used uh and they are the 95 printable ASCII characters as you can see from here and basically What's Happening Here is that when I uh for instance and this is someone going into telnet so they've talented in they have connected and now I've told it basically to create some characters and that's what it's doing here and it's using all the characters that are available to it in ASCII and you would usually use this when you're setting up a printer testing a connection to a device or printer it doesn't really have much of a function otherwise you can see that the content is not very important but all it's doing is basically creating characters or content for us to test with the next one is the daytime service report and this is what it looks like and you can see that it's presented in the following order it's going to show us the day of the week the months the day the year the hours minutes and seconds in that format and finally and very importantly the time zone the reason the time zone is important is let's say that we're looking at this daytime in an email and sometimes the headers are going to use this same format all right that's provided by the daytime service and tcpap well I can see that oh yeah it was sent at 1845 which that's military time so this would be 6 45 PM in sort of our lingo but by knowing the time zone I can actually determine where in the world it was sent from and therefore for instance this was sent on Pacific Standard time which is in the U.S then uh I would know that this is three hours later or 9 45 in the Eastern Time Zone now none of the other uh as we've mentioned none of the other uh Services have any sort of output I can show you but just to recap what we've talked about we described and demonstrated really briefly the TCP simple services and these again include a character generator we're really going to see this a lot when we're dealing with printers it's just generating ASCII code we looked at the daytime service which is presenting the day the time and also don't forget the time zone which is really important we looked at the discard service which automatically deletes messages that we don't need and so there's really nothing there Echo simply repeats or Echoes any services or a message that are happening internally and finally the quote of the day takes a random quote selected by the administrator or taken out of a etc folder in the system 32 quotes area so that would be if we had the root which would be like system 32 and then Etc and then quotes that's where it's going to draw something from and again this is also used for troubleshooting purposes I showed you examples of these two because they're the only ones that have their own format all of the others the form is not as important all it does is take other information sort of regurgitate it now in the next module we're going to take a step further and talk more about some of the tcpi tools and commands and get into the operating system when we do so [Music] thank you tcpip tcpip tools and commands so in the last module we talked about the simple services that tcpip provides and those you may or may not see on the network plus exam however in this module we're going to talk about some of the most essential tools when it comes to the tcpip suite and I can almost guarantee you you're going to see these on the exam so we're first going to discuss and demonstrate all of the tcpip tools and some of these tools include the Ping command and some of these we might have seen previously as well perhaps an A-Plus and some of these also I'll go into the operating system and show you so we're going to see the Ping command which basically tests for connectivity we're also going to look at the trace route command which basically traces a ping route and remember when we were talking about um uh protocols previously we mentioned the icmp protocol the control messaging protocol and that is what a ping and a trace route command use or these types of packets so we're also going to look at a protocol analyzer not necessarily a command line tool but something that allows us to analyze the protocols uh or rather the packets that are going in and out of a network or system we'll get a port scanner sort of does the same thing we'll talk about the difference between these two we'll also get something called nslookup and NS doesn't ring a bell with you that is like DNS or name server lookup how we convert between an IP address and a fully qualified domain name such as Google we're also look at the ARP command which allows us just like NS DNS which does a name to an IP address ARP is what is responsible for routing and allowed us to convert between an IP address and a MAC address or physical address so you can see where this is really going to come into uh into handy when we're talking about routing and switches finally we're going to look at the route command which can present us with routing tables and it's specifically more or less used when we're dealing with routers not so much in Windows all right so first the Ping command the Ping tool in the Ping command are extremely useful when it comes to troubleshooting and testing connectivity basically what the tool does is send a packet of information in that packet again is icmp through a connection and waits to see if it receives some packets back this is not unlike when you used to see the radar screens on a computer on a TV or program we're talking about with um uh submarines for instance and you would see basically a submarine here and you'd hear a ping coming off of that so it gets its name from that sort of sound so the data literally bounces or pings right back if there's an established connection can be also used to test the maximum transmission unit or the mtus and remember we talked about that when we dealt with an MTU black hole was in a previous lesson this is the maximum amount of data packets that can be sent over a network at any one time or the maximum size of that data packets so using this you can test the time it takes in milliseconds for data to travel end to Android to other devices on the network this can also be done on the localhost and you remember the localhost is 127.0.0.1 that's the IP address for it and we can test this all by opening the command prompt and typing in ping and then the IP address so let's take a look at this uh for just a second if we're here and we have our Command Prompt and I wanted to type for instance ping 127.0.0.1 which would be the Local Host I can tell that my time is less than one millisecond which makes complete sense since there should be no loss of data it should take no time and you can see that no loss of data right here right because we're sending it there and back and obviously we're dealing with ourselves the local host or the 127.0.01 so it shouldn't be an issue and if we do that notice that when I use localhost I'm using my own name and and it's also giving the IPv6 IP address here now if I clear the screen for a second I can also for instance ping google.com and you'll see that it actually sends first it figures out what the IP address is and then sends that and it gives us the time that it takes to get there and back it also gives us some statistics for instance it was sent four of them were sent for them received zero lost and so we know that on average this is taking 13 milliseconds to get from us to Google and if you imagine that this was a local host uh or rather a sorry a local uh server on my network and I was rebooting that server this could help me tell whether the server is back up again and one of the things I might want to do with that and I'm just going to use The Local Host right now is use the slash T um switch and what this will do is it'll continually ping the same IP address over and over again now I so for instance if I was waiting for a server to come back online this would be an easy way for me to tell whether it's come back online or not and I could exit that by pressing Ctrl C all right so the next one I want to talk about is trace route which actually goes hand in hand with ping because he also uses that icmp data packet or protocol it basically tells us the time it takes for a pack to travel between different routers and devices and we call this the amount of hops along the uh the network so not only tests where connectivity might have been lost but it's also going to test um the time that it takes to get from one end to the other end of the connection and it's also going to also show us the number of hops between those computers so for instance between me and Google there might be four different computers and so each one of these is called a hop and we can measure how far the packet is traveling before it gets back to us now I can also use this to test where a where a downed router might be or where in the connection a down to router might be so if we go in here for a second and let's take a look at the command prompt here and let's say I go to trace route google.com now what's going to happen is it's going to start saying all the different hops going to tell me how long it takes to get from one place to the next and we can see also where it's so right here we're still in New York let's see NYC I can probably guess this is some place in my ISP and now it looks like it's starting to go out get further out and we can see that the amount of time it's taking is also more and more so between getting between me and and Google you can see how far we're having to go until we finally get to the google.com web uh server which would be right here and we know it took about 10 hops now you can see it has a maximum of 30 Hops and we can actually set that in the switches if we need to but I wouldn't worry about that for the exam and just to show you what it looks like if I'm tracing the Local Host you can see it only takes one hop obviously because or not even a hop because it's myself I should be no route to get to me now going away from the command line for a second I want to talk about what's called a protocol analyzer or a network analyzer this is an essential tool when you're running a network it basically gives you a readable report of virtually everything that's being sent and transferred over your network so these analyzers will capture packets that are going through the network and put them into a buffer zone now this buffer zone just like the buffer zone we're dealing with YouTube or Netflix and buffering a video is going to hold on to these packets and we can either capture all the packets or we can capture specific packets based on a filter it can then provide us with an easy readable overview of what is contained within each packet this allows the administrator total control of what does and doesn't pass through the network and can also stop potentially dangerous or unwanted pieces of data to pass through the network undetected and so what you can see here is if this is our cloud or our Network we're going to call this a TCP Network just because this is basically our our Wan and here let's say I have one Lan and another land I'm going to have a protocol analyzer a network analyzer in between my network in my land that way I can analyze exactly what's going on some ways this might also take the form of a firewall now this is different from what's called a port scanner a port scanner does exactly what it sounds like it basically scans the network for open ports either for malicious or for safety reasons so it's usually used by administrators to check the security of their system and make sure nothing's left open oppositely it can be used by attackers for their advantage so uh if a poor if I'm on the internal I might use a port scanner to scan my firewall to see what's going to be allowed through I might also put my port scanner over here and have it try to come in alternatively a hacker could use a port scanner to go through and scan for open ports if there are any open ports it can then use those to try to get into my system so I can use it either as a white hat or as a black hat white hat means a good hacker black hat means a bad hacker now let's get back into uh our command line for just a second here the name server lookup or NS lookup and again whenever you see NS as in DNS domain name system you can think that has something to do with name server or name system it's used to basically find out uh what the server and address information is for a domain that's queried it's mostly used to troubleshoot domain name service related items and you can also get information about a systems configuration now dig actually does the same thing but it's a little more detailed and it only works with Unix or Linux systems so here's an example of what the NS lookup would look like and you can see if NS look up here and then what did we do well we asked it for Wikipedia's name and up it pops the IP address and it also tells us when whether it's authoritative or non-authoritative authoritative would be a DNS server that's somewhere out on the internet that is definitely has all the information non-authoritative means it might be a local one so if we were to look at this for a second for ourselves let's do NS lookup to go into the utility and now we could for instance look up uh google.com and it'll tell us all the different IP addresses that are available for google.com yahoo.com maybe even microsoft.com CNN.com etc etc so you can see all these different ones that are coming through now notice that CNN.com actually wouldn't let us out and neither would microsoft.com that's because they're actually blocking the they're filtering out the type of uh ports or protocols that are going to be allowing uh that are going to allow like the icmp Ping so if we were to go out of this for a second and by the way you do that as Ctrl C and if I tried pinging microsoft.com you'll notice that it actually doesn't come back and that's because they're actually shutting out icmp packets from going in now another one related somewhat is what's called ARP or address resolution protocol we actually talked about this previously and it's you really use to find the media access control or Mac address or the physical address for an IP address or vice versa remember this is the physical address it's hardwired onto the device the MAC address is the system's physical address and the IP address is the one again assigned by a server or manually assigned in a way this would be like your phone number and this would be like your social security number which is given to you by the government the way it does this is we're actually going to send out Discovery packets in order to find out the MAC address of a destination system and once it establishes that it sends that Mac address to the sending or receiving computer now the two computers can now communicate using IP addresses because they can both actually resolve to IP addresses so basically I want to send something right so what I'm going to do is I'm going to go out hit a router the router uses arp in order to get the MAC address to the sending computer and now we can talk directly because now I know what your Mac address and IP address equal finally the route command is extremely handy and can be used fairly often it basically just shows you the routing table which is going to give you a list of all the routes network connections and so on that the user has the option to then edit now the reason you might want to edit it is if for instance in your router you want to tell it to use one route instead of another so an example here shows us The Gateway the mask so draw these really quickly and the interface and the sorry the metric as well as the interface and these are all numbers so these might not mean a lot to you but if you had a guide and you knew where they were going if you knew what your interface was for instance is it a wireless internet base or was it a your wired interface that would prescribe a specific number the Gateway is going to say what Gateway you need to get out and the subnet mask and you could actually add specific information to this to create your own routing table and this you would do really not so much on your computer but more if you're working on a router say Cisco router so you can do to tell it exactly where you want information to be routed so just to recap we discussed and demonstrated several TCP tools including ping which we're really going to use to test connectivity and remember you want to hold on to the Slash t-switch which is going to do it indefinitely trace route which is going to measure the Hops and can also tell you where uh connection has been lost a protocol analyzer which is going to look at or network protocol analyzer we're going to look at all the protocols coming in and can actually filter them in or out a port scanner which can be used to show open ports either as a security precaution or if I'm trying to infiltrate your network the NS lookup which is that name server could also be dig by the way which is on Unix systems and this is going to allow me to get my IP address to a fully qualified domain name ARP address resolution protocol which is specifically going from IP address to MAC address it sort of really allows routing to occur this is really a principle in routers and finally the route command which allows us to edit the routing tables and would be really useful if I was using one of my servers as a router you're not really going to see routing a route command on the network plus exam but I guarantee you'll see all these others mentioned so uh now that we've finished up this very brief lesson on TCP the tools and the simple Services we're going to go into Lan Administration and implementation a bit more in depth [Music] thank you foreign Network Administration and implementation so in previous lessons we've discussed a lot of the tools the networking fundamentals the theory and so on and now we're going to get into a little more of the Practical side and that's in creating and maintaining a local area network wide area network and so on and so forth this module is certainly just an overview of local area network and some of the best practices that go along with it as we get more in depth over the coming lessons and modules we'll talk more about the specifics and what we need to do so in this module we're going to talk about an overview of a lan kind of go back over what it is and also um when we'd probably want to use one and then we're going to identify the steps to setting up a lan including using a network plan having backups creating proper documentation auditing and security so first what is a lan well there are two types of networks as you recall one is a lan and the other is a Wan a land stands for again a local area network and the local area network is really any sort of local or geographically um uh specific Network now Wan stands for a wide area network and we're going to talk about that in more depth in the future so because Lan is restricted to one geographical location such as a school or a small office building it's a lot easier to administer and requires a certain specific set of skills since it's so localized it also has higher speed capabilities than a Wan and it's often a lot less expensive so here's an example of a local area network the internet connectivity comes from the server which is going to also go out to the WAN which would generally be represented by a cloud the WAN being the internet and we can see that there is a switch here which connects each one of these PCS wirelessly perhaps has a PC connected through it thanks to a wireless access point perhaps connected to the switch or router by the way here this server is acting as a router and we might also have the network connected printer very simple but effective Lan here now at the heart of every network is a server the server is really what powers the internet connection to every device that's on the network and provides um devices on the network with resources and other sorts of information now in some cases we're not going to have a server network but we're going to assume here that we're talking about very technical Network okay and the first step to implementing a local area network is to generally set up the server or if we don't have a server to set up the router or the Soho router in a small office home office remember the server is really going to serve up resources it's going to serve up a DHCP server so on and so forth so the word Server doesn't necessarily mean a freestanding personal computer or a more powerful computer it's really just the device that's at the center of our Network now usually we're going to do this with some sort of professional setup sometimes we'll have someone else come in and sometimes we're going to do it ourselves now the network topography and design is also pretty important we need to figure out how we're going to set up the network we talked about different topographies previously so we probably are going to want some sort of star Network if you recall what that is we might for some reason have a ring if we have a really intense local area network all this is usually going to be used in a Wan setting so really what we're going to see usually is a star and as you can see everything is hardwired and this is a bird's eye view of how we're going to connect this network so you can see we see each device plugged up we see where every device plugs in for instance this printer plugs up directly to Mike's PC so if you're having a trouble problem with the printer we know that actually the PC could be the problem not necessarily this chord here and so knowing where everything is set up and how everything is set up is really important as you go forth and of course important before I start to create a huge Network by the way your network and your plan probably a lot more complex than this but try drawing out your network at home and see if you can do it as well now backups are extremely important when I have especially Enterprise setup the loss of data that can occur could take us out of operating and if I'm talking about a network that is running Bank information or health care then I really need to potentially stop or avoid this critical loss of data so regular backups are key now there are a lot of different ways to do this and we'll talk about specifically some of the difference between an incremental backup and a differential backup disgusting a plus as well but there are some other Surefire ways that we want to do this first all users on the networks need to be regularly saving and backing up their own work then we might want to have an outside service also taking care of our backups so I might want to have the backup going out to a cloud or to a Wan in this case I probably have and this computer is representing My Lan all of the information going to a central service and then going out if I have a server and all of the devices are hooked up to the server then they're going to feed the server with the information once that information is on the server then I can make sure that battle goes out to the cloud the important thing is to centralize where your information is being saved if I have for instance data being saved to various computers and those computers don't have a central place to store all the data then backing up simply the server is not going to do it a map to go back up every individual computer and that really doesn't work so what we really want to have is a centralized backup system and sometimes we want to have redundancy in this system by not only backing it up locally but backing it up out to the WAN or alternatively having tapes that we're going to take off site in case God forbid something happened to my backup plan now it's also important that we document our Network and once we've documented it we need to continually audit where our Network's weaknesses and strengths are so I want to keep track of everything that's on the network including the hardware the software diagrams that we have numbers serial numbers Etc we also need to audit the network for security strengths and weaknesses we might do this by using a port scanner by having some sort of centralized virus scan program like we'll see in a minute and maybe even by hiring an outside security firm to try to hack into my system so I can see where the weaknesses and strengths are all this information is going to be key in recovering in case of major data loss and that's the reason I want to always just keep a nice long paper trail sometimes you might want to print this stuff off too because again the computer goes down I can't access anything that's digital or throw it up in the cloud then I don't have to worry about it now when we kept the management and troubleshooting we always want to make sure the network is running smoothly and since you're the administrator you're the person who has to be monitoring and managing everything that's going on now when there are issues you want to troubleshoot and solve the issues where they arise using the OSI model can be really helpful in this case because you can determine where the issue is occurring for instance if I'm having a trouble getting out to a certain website but everyone seems to be getting out to information then maybe the DNS is the problem if for instance new devices can't get on the network but if I manually assign them an IP address it does work well then probably my DHCP server is is getting funky again this is just an overview we're going to talk about all this in more specifics as we go forward so I need to take a look at what the error is figure out what the problem is and get to the root issue especially because what I'm really going for here is what's called five nines which means I want to be up 99.999 of the time that's like five minutes of downtime per year that five minutes however can be really a big issue this also means I want to be updating with Windows updates and I want to be providing as much information as possible to my network and my network staff and even the individuals who are using the network as possible finally when it comes to security and virus protection I want to make sure to audit and protect prevent the attacks before they can happen so I'm going to audit it and once I audit I can see what sort of the issues are if I notice that there's no Virus Protection Program then I'm going to want to use some antivirus software if I notice that there are open ports getting out to the server through the firewall then I'm going to want to use that if I notice there isn't a firewall I'm going to want to have to put a firewall up so basically all the things I can do there's no one size fits all practice what you really have to do is use the skills that you have in order to audit the system and then prevent the attacks before they happen using a number of different tools might even use something called an IPS or IDs which would be uh intrusion protection or intrusion detection service or scanner all right so just to go back over this it was a very broad overview of what a local area network is and some of the things that we need to do in setting up maintaining a land including creating and having a network plan performing regular backups providing documentation keeping holding on to that documentation auditing our Network to identify weaknesses which is the main reason for an audit we also might want to use the audit to identify bottlenecks or slow issues that are going to cause speed issues so on and then of course having proper security such as virus scan programs intrusion detection prevention systems firewalls and so on we're going to talk all about this and more in the coming lessons but this was just a broad overview to get a sort of set up [Music] thank you local area networks switching so in the last module we talked about local area networks in general what they do how we set them up how we administer them but in order to have a functioning local area network one of the most important developments that we had was called switching if you recall earlier on we talked about the OSI model and if you recall the OSI model went from level one all the way up to level seven now level one was the physical layer and on there we talked briefly about a device called a hub now the problem with the Hub was whenever data went from one computer into the Hub The Hub spouted all of that data out to all the other computers on the network this created a lot of broadcast traffic because the Hub itself worked on the physical layer all it did was repeat all of the bits that went into it out to all the other devices but now we have something and we've had for quite a while a thing called a switch and this allows for switching which operates mostly on level two of the OSI model which if you recall is the data link layer switching allows us to have a fully functioning local area network because it allows devices to talk using the MAC address or the physical address of the computer so in this module we're going to talk more in depth about what a switch is how a switch operates which I just touched upon a bit and then I'm going to talk about a couple Advanced switches you need to know about for the network plus exam these are the multi-layer switch also called a layer 3 switch or a Smart Switch and then we're going to talk about a Content switch which as the name implies deals with the content in the packet not just relaying the packet of data itself so a switch is an extremely important part of a functioning Network so let's look for a minute about a light switch a light switch essentially has two pieces of wire attached to it if we look at like so I'll put the little switch right there and when the switch is flipped in One Direction the circuit is completed when it's flipped the other way then the circuit is sort of broken and so the light turns off in a way an ethernet switch follows the same principle except it's not only attached to one single wire and cable but to many some switches can even have upwards of 200 cables attached to them now these ethernet switches are used to connect many if not all of the devices on network and it establishes a flow of data between them this switch like a light switch makes a connection between two different cables and allows the data to flow specifically between those two devices now Lan switches are used to send data from a single device to another sometimes uh the and sometimes even multiple devices there are devices as I said called hubs but these do something different so what the switch really does here is it allows data sent from one device to go specifically to the other device that it's meant for and it does this because it knows the MAC address that it wants to send to now it doesn't necessarily know where that Mac address is on the network all it knows and it puts this into the packet remember we talked about that it puts it into the header of the packet the address which would be sort of like the phone number or the social security number of the computer that wants to receive the data the switch then has a table that says in each port so if we had Port 1 2 3 4 and 5 it would say the MAC address connected to each port and so when Port 1 sends data meant for a MAC address it knows oh I'm going to send that to Port 5. now it could also do this for multiple for instance I'm going to send it to Port 2 and port 5. the key difference here as I pointed out in the very first slide was rather than a hub which broadcasts out to all devices the switch creates a single switch between two specific devices and closes a connection what this does in effect therefore is reduce broadcast traffic and allow the network to run much more efficiently than a hub allowed now there was a time when networking devices only served one purpose and their functions were specific to that type of device but over years things have evolved so now devices can do multiple things now we see this multi-layer switch or what you might also see as a layer three switch or a Smart Switch what it does is it is not only a switch it's also a router this is the reason why it's called a layer 3 switch I brought up the OSI model on the very first slide layer 1 physical layer 2 data link and if you recall layer three let's use our mnemonic device please do not throw sausage pizza away so this is the network layer if you recall we mentioned briefly that routers which we'll talk about in more depth later operate on layer three that's because IP addresses operate on layer three so a switch can not only look at the MAC address but a multi-layer switch one that operates not only in Layer Two but also on layer three can also look at IP addresses so because this switch operates as both a router and a switch it can send information between several different networks so here for instance I have Network a and network B and let's see this PC wants to talk with the server on network B in the old system uh unless network uh unless the server was actually connected directly to the switch there would be no way for the two networks to sort of speak to one another but because we have a device here that's perhaps operating as a switch and a router it can route the data onto a different network using an IP address in some ways you could think about this as the Advent of the area code when we had a phone number which was only five digits or uh sorry seven digits such as um seven two three five four one one we could talk to anyone within our local network if we knew this number when we added the area code we were allowed to then dial out to other states and then we were allowed by putting an international code to dial out to different countries so we're allowed to go then outside of our specific Network in this way we're not just dealing with Mac addresses we're dealing with IP addresses and as we've talked about IP addresses are assigned by for instance a DHCP server and so as a result they're more temporary they're not hardwired onto the device and it not only allows for routing but it makes it a little more complex to figure out where a device is at any one time we'll talk more about that in the next module the important thing here to realize though is that a multi-layer switch operates both as a router and as a switch because it works on layer 3 and layer 2 which means it not only reads Mac addresses but also IP addresses now the next type of switch I want to mention is something called a Content switch the name content should give away what we're about to talk about here now these are not really used as much as we see in today's networks because they're quite costly but a Content switch will actually analyze the data it receives and forward it based on its content only so rather than dealing with simply an IP address or Mac address it actually looks at what's inside of the of the packet if we have a MAC address here and then we put an IP address on the outside of that in order to tell where to go it's actually going to look inside and look at the data and determine where that content is going to go these switches are also sometimes called load bearing switches because they can evenly distribute data based on the type of data there is in the appropriate destinations which can alleviate stress on a single server or device so for instance if I erase all this for a second let's say we have for some reason and let's say we have a router right here which allows us to connect out to the internet and then information comes in straight from the router to the content switch and we don't know where the information is set for or let's say we have six different clients or servers it doesn't really matter that each could operate under the same sort of IP address for instance we're going to put them all together or group them the content switch can say which one it's going to go to based on the type of information it's receiving so for instance email is probably going to go to one computer whereas web is going to go to another whereas the FTP might go to another and the packet itself doesn't have to know which computer it's going to the packet just has to have an IP address and or Mac address and then the contents which itself based on the content is going to send that over another way to think about this is if I'm dealing with some sort of firewall and I want the firewall to put certain types of data into a um filtered area that needs to be scanned for viruses so this is really going to help me alleviate uh certain processes and also help keep my network safer and we'll talk about other devices that do this as well but when we're dealing with the content we're dealing with further up on the OSI model so we're not just dealing with layer one or two or three even we might even be dealing with layer four to some extent so just to recap we first talked about what a switch is a switch again allows for a direct connection between two devices or more the important thing to hear to realize is that the devices communicate directly because the switch creates a circuit between those two devices Within a box based on ports now how it does this is it creates a table defining which ports are connected to which Mac addresses again a MAC address is the physical address that's built into a device when it's made this is different from a hub which just broadcasts everything so if we were to create an analogy we could say broadcast which would mean all the data going out to every other device is to a hub what unicast or multicast is to a switch we also looked at some Advanced switches you need to know about the first is a multi-layer switch which operates on layer 2 and 3. our usual switch because it's only dealing with Mac addresses is dealing with the data link layer which on the OSI model is Layer Two a multi-layer switch is also operating on layer 3. it also routes so it is not just a switch it's also a router a Content switch is even going further up the OSI model and analyzes the content in a packet to determine where to send it this is also why it's called a load bearing switch because it helps reduce the load on a specific node by sending the data out to several different devices that can all deal with the same content in a device now we're going to talk further about routing in the next lesson [Music] spanning tree protocol so what is spanning tree it's defined by the IEEE 802.1d standard and basically it allows switches to communicate in order to prevent loops on our switch Network it runs a mathematical algorithm it finds out on blocks which ports would be the possible causes of layer 2 loops basically a loop will occur on our switch Network when there's more than one path for a frame to take and this could cause obviously confusion as I'll illustrate in a moment so it's a real simple illustration here with our diagram so switch one for example will receive a frame on its fast ethernet zero slash one and it will flood it out of its next interface fast ethernet zero slash two and remember if there's 24 interfaces then it would be flooded in them out of all 24. now switch 2 would receive this um and the address would be for host a and it would be firstly received by switch a switch one and recognize that host a was connected to fast ethernet 0.1 unfortunately that address would come out of the bottom of switch one go around and reach the bottom of switch two switch two then thinks that it knows the way to get to host a and the direction to go is through fast ethernet zero slash one it will send that out of fast ethernet uh sorry first ethernet 0-2 and it will send that to zero slash one now we have a problem in that the ports on the switch all think that they can release reach host a and that isn't in fact the case now there's no time to live field in layer 2 frames so that would go around around the network until every single switch thinks it knows how to get to host a and it would bring your network to a grinding halt so there's a mathematical algorithm was created and it's based on two key components the bridge ID for bridge ID you can basically read switch ID it's the same thing and the path cost so these are contained inside the frame Bridge ideas and eight byte field consisting of the bridge priority and the MAC address the base Mac address of the switch the default Bridge priority is 32768 and then this is added to the MAC address now I've issued a show version on a switch and it showed the base Mac address among other information and each one will be different so the path cost is used to calculate the proximity to neighbor switches the higher the bandwidth the lower the default cost so we can see the 10 gigabit connection here has got the lowest forecast allocated to it so there's a four-step path selection process so the lowest route to bridge ID the lowest path cost to the root Bridge the lowest sender Bridge ID and the lowest Port ID and it will go through this four steps until it makes a decision this all happens after the exchange of bridge protocol data units which are called bpdus so let's have a look at our diagram we have three switches here and just to keep things simple we've given them the Mac addresses of all A's or B's and all C's they're all connected so we could possibly have a loop here unless something is done to close down one or more of the ports so there's a root Bridge election firstly then there's root Port selection then there's a designated Port election the bridge with the lowest Bridge ID is selected as a route and remember it's a combination between the priority and the MAC address in this case the lowest Mac address is going to be the one with all of the A's because that's a lower number in hexadecimal so root Port is the port closest to the root bridge now the route bridge will not have any root ports because it is the route Bridge so its ports will all be known as designated ports you can see switch two and three has elected its closest port to the uh route Bridge as fast ethernet zero slash one every bridge you set the root Bridge must elect the root ports and each interface adds a cost so as it goes as the frame goes through different interfaces the cost is added you can see fast ethernet 0 1 is 19. as it gets to fast ethernet 0 2. that Port cost is added again and 19 plus 19 costs have been 19 each uh comes up as 38. so fast ethernet 0 1 wins the designated Port election and designated report sends it receives traffic on the segment to the root Bridge only one designated Port per segment you can see there's a segment at the bottom here if I see Zero slash two on switch two and three the toy goes to the lowest root Bridge ID lowest root path cost lowest sender Bridge ID and lowest Port ID and you can see on switch two and three the lowest out of the two would be the switch with the number MAC address bb bb and so on the port States for STP can only be one of the five following it's forwarding it's learning it's listening blocking or disabled all right so we've covered a fair bit there I only wanted to give you a taster STP and um there could be a lab on this I haven't decided yet obviously you'll be digging into a lot more detail when you actually come to do the CCNA thanks for listening [Music] welcome to modulate lesson 2B power over ethernet or Poe what is poe the benefits components the power supply equipment we love our abbreviations there PSE n-span mid span power devices modes in Poe standards how does it work what is it first Poe is a technology that allows a um a device connected to an ethernet cable to receive the following electrical power and data now obviously a device connected to an ether cable was already going to be receiving data because that's what um ethernet was designed for however what it wasn't initially designed for and some very clever people [Music] um found or realized away and tested it is to deliver power and it's got all sorts of uses we're talking in the context of networking however I recently bought a guitar effects board that plugs into the back of my amp using a ethernet cable and I thought it was going to come with a power supply but as soon as I plug the ethernet cable in it actually powered up the pedalboard and the pedal board offers a whole bunch of effects you can record about five minutes of Music Loop it add other tracks onto that Loop and a whole bunch of stuff so um very clever technology and it's got a multitude of purposes and it's just one of those things when it's invented you think why didn't somebody think of that earlier the power devices that support Poe only operate from the piracies through the ethernet cable obviously there's a finite amount of charge or power that you can push through the cable because it's quite a thin strand of metal but um obviously avoid the need for additional electrical wiring are you your power supply unit and all the wires that come with that and as we all know every single power device has got a different and socket a jack on it and it just makes it very awkward to keep a track of which is which and then obviously your power supply can die making our lives a misery so what is it we're supplying electrical power through the electrical ethernet cable in order to power devices I know I'm stating the obvious here and of course is uh designed for beginners as well very handy for voice over IP uh telephony very useful indeed because it just um saves those extra wires and cables wireless access points network cameras um very big in the field of security especially industrial security and shops and warehouses since the devices can consume the required power from the ethernet cable there's no need for the separate local power supply if the device is an outdoor wireless access point or a WAP it supports then we can do the following we can send it electrical power and we can send data through the cable eliminates the local power source it's saving you money no great no need to upgrade the existing CAT5 or coccyx cabling which is another Lifesaver and a wallet saver for companies no need to purchase the power outlets electrical wiring I'm not sure if I'd talk about that in a moment as well but it's just another thing uh that that wouldn't possibly go wrong I can't remember if I've put this in a slide somewhere so you've got one less um point of failure there very easy to install basically you just plug it plug and play you can install it even though locations that are hard to reach because there's no need for local power increase reliability um less risk of power interruptions caused by human interference because the device is essentially powered a lot of the time our networking equipment has a redundant power supplies as well and backup generators especially if it's an ISP so they'll keep working enhanced Operational Support and monitoring and Remote Management we can do through SNMP so we can power the devices and perform different operations over the network very handy I know I could remotely reboot different devices on my remote rack um if I couldn't reach it and I didn't want to pay a tech to go and power cycle stuff I could just send a message for the power unit to reboot if it needed to all right two basic components your power supply equipment and your powered device your PSE is the a unit that adds electrical power to the ethernet cable you've got n Span and mid span the end span is it refers to a switch that supports Poe in addition to its switching role so we can do both these switches are capable of sending electrical power and data to the device mid-span refers to a standalone inline injector that provides power to the Ethernet cable so it's not built into a switch this is a situations where a switch doesn't have the built-in Poe it could be an older model or a cheaper model for whatever reason so you can pass the data coming from the switch to the inline injector and can output the same data but it adds power to the um points of the cable there the power device supports Poe receives the power via an ethernet cable now in Poe there's two different modes for combining the following data and power of the ethernet cable the two modes are not very imaginative unfortunately mode a and mode B suppose it could have been one or two or Jack and Jill mode a the electrical power and the data are combined on the same wires over the ethernet cable this is called Phantom powering mode B the electrical power and data are carried on different wires which is more common separate the data and power inside the ethernet cable so in the internet cable if you've got a pair of wires carried only the power then the other pair of wires would carry only the data uh First International standard was 802.3 AF ratified a long time ago June 2003 and it defines um a power supply of up to 1.54 watts of DC uses 48 volts as growing demand for more power over Ethernet cable so the standard was updated and 802.3 Poe Plus this was adopted back in 2009 and it defines the following a power supply of up to 34.2 watts of DC power using 48 volts both the I um IEEE 802.3 AF and 80 are now included in the ethernet standards they've all been combined together as we know from earlier presentations the ethernet cable has four pairs of Twisted wire this is cart 5e and Cat6 uh for and we already covered earlier that 10 base T and about um 100 base T ethernet only use uh two pairs of wire to send the data so this leaves us some spare wires two pairs of spare wires so electrical current flows in the loop powering the electrical components such as bulbs and fans the loop is an electrical circuit and since the electrical current flows in the loop we need two conductors to deliver power over an ethernet cable uh typically we use 48 volts that says sufficient power to transfer over the cable and it's safe for users so it's not going to injure anyone now if you plug a Poe device into one that isn't designed for use with Poe then you could cause damage and fry it and in other words and the PSE sends a lower voltage to a device to detect the characteristic signature of a compatible PD if he takes a signature then it knows the 48 volts can be applied the PD lets the PSE know how much power it requires to operate so this is to save a surge basically on the um line now too much power has been sent the requirement of power is classified in the power classes shown below probably worth making a note of these write them down just in case it comes up in the exam difference between the following power supplied by the PSE power received by the PD account for lostpower now there is a maximum distance which matches in with the ethernet standards and maximum support distance is 100 meters there's a new standard which increases the power available and uses a wide range of the following devices Thin Client Terminals and pointer sales stuff in shops video conferencing so I think that's all we need to know we've covered Poe the benefits the components the PSE end span mid-span the power device the the modes for Poe which is a and b uh the standards and how does it work so that's all for now thanks for watching [Music] local area Networks routing so in the previous module we discussed switches and as you remember they're very important for the functionality of a local area network now when we talk about connecting several different local area networks together through the internet we have to deal with how a switch which again is based on Mac addresses the physical address on a computer can find the MAC address of a computer halfway across the world and the way it does this is by assigning each Mac address uh an IP address now when we start dealing with IP address we deal with a completely different type of device one which is called routing and the process of routing is what really allows the internet to work and so in this module we're going to talk more about the devices that allow routing to work called routers so first of all we're going to Define what a router is and then we're going to talk about how it functions which is also called routing then we're going to identify something called static routing just like we've talked about dynamic versus static IP addresses we also have Dynamic and static routing obviously one is more resilient than the other but there are certain instances in which we want to always go to the same location and that's why we're going to have static routing then we need to cover some terms that you might see when you're dealing with routing these terms are hop counts costs latency and convergence so we're going to cover all those terms so you have a good idea in case you see them on the exam what they're referring to so a router is essentially like an extension cable an extension cable connects two sources of power and in this case a router connects to networks together in order to make a larger Network in networking the router is used to connect two networks together and give a clear route for data to travel between these two devices now in smaller settings such as houses or a small office home office or Soho the router connects the device is to the Internet so for instance you have uh your computer and you have a laptop and perhaps you have some sort of Apple TV device or some device that's connecting to your TV and the internet and all of these connect through what you call your router now this Soho router is actually doing several things it's not just a router but one of the things that it does is it allows you to connect all of these devices in your internal Network otherwise known as your Lan out to the large Wan or wide area network that exists in the world this is called the internet so in a larger scale environment the routers are used to make bigger Network pieces so if you can imagine that instead of just having my own home I have say a number of buildings across a city or a number of buildings across the world and I want them all to talk to one another and be able to locate one another as though they're sitting right next to each other this is where routers are going to come into play this is also why routers do a lot more and are more expensive than switches it's also why we need fewer of them now in modern networking the router is either going to be a dedicated device or it could be a server with a routing functionality meaning it's a large computer with two or more network cards or Nicks in it so that you can have traffic going in and then traffic going out now when a router receives a packet of data from a client device it reads the information in the packets header and determines what the destination of the packet is after it finds out what the destination address is it looks at a routing table in the router in order to determine where the packet is going to go in its next route so for instance let's say this PC here which for sake of ease we'll call pc1 wants to talk to PC2 now it has an IP address in mind and so what it does is it goes perhaps through a switch but eventually to the router at the end of its LAN and it says hey I'm looking for this specific PC now this router has what's called a routing table which sometimes we're going to call an ARP table because ARP again the address resolution protocol is what allows routing to occur it's this protocol that we've talked about which allows for a table that would say for instance one goes to IP address 192 whatever whatever Etc and so this router would look for this information if it doesn't know it it's going to say I don't know it but I'm going to go to the next router that might goes to this router and the second router says oh yeah I know where that computer is and then can forward the packet onto the computer it also tells this router the first one which we'll call let's say router a and router B where that destination was so it can add it to its ARP or routing table and if you imagine this is only what we call one hop because there is one hop between these two routers but you can imagine in the entire world if I'm traveling from say here in New York City all the way to Australia for instance I might have to take several different Hops and also if you imagine there are probably many different routes that I can take to get to a specific computer if we imagine that the circles are the two computers and the squares are the different types of routers and we have them connected like so well there are a lot of different routes that a packet can take to get from point A to point B and so we were allowed on WE rely rather on routers to tell us which path it's going to take it could take this path or it could take this path and so on and so forth and so uh depending on the number of hops and a number of other things we'll talk about in just a minute it'll determine where the packet needs to go in order to get from point A to point B some other things it's going to determine too or what if there's a cut in the line well now it can't get here and so instead it'll say well let's try one of our alternate routes as well now in the previous slide I talked about how routers might talk to one another in order to automatically update their routing tables this way two routers always know how to communicate with each other or one computer on one side of the world can always get routed or the information sent from one computer on one side of the world can always get routed to the information on another side of the world but in some instances we want to tell a router exactly where to send information destined for a specific Network now it might not always be the most practical way but sometimes it's necessary so static routing is when a routes and routing information are entered into routing tables manually and this can be time consuming and because it's prone to human error it can be error written and can cause some problems so this is why it's only done on very small systems or on ones that are very internal and controlled now in order to statically add a route we're usually going to use something called the route add command now this is the sort of thing you might use if you were adding a route to a Cisco router or to a Windows machine for instance that was acting as a router or even a Windows machine that's at the edge of a network and needs to go out to another the way it works is we use the route add command with the network name The Mask or the subnet mask and the IP address of the Gateway so this tells us if we want to get to the network 192.168.2.1 we need to go to the subnet mask 255.255.0 and the Gateway 192.168.2.4 now all this information would automatically be done uh dynamically by most routers but in some cases we're going to want to add it or statically now this isn't something of necessarily seen come up on the network plus exam but I did want to clarify it and go over it just briefly in case you ever saw it in the field since this might be something to do something that your administrator or your boss asks you to do for whatever reason or maybe something you want to play around with if you need more information simply Google the route add command but again I don't think you'll see it on the network plus exam finally I mentioned that there were some important terms we had to mention when we talk about routing the first is the hop count this is the number of hops it takes to reach a connection or before an appropriate connection is made if you remember when we used the trace route command remember that was trace route it went through a number of hops or a number of routers until it got from our computer to for instance Googles so if our computer and the destination computer are represented by these two circles and let's say we have our internal router so for instance perhaps we are in a 10.0.0.xnetwork and then they're on their own network as well let's say that this is a for instance uh 124.68.24.3 Network now we need to get from hours to theirs and so let's say there are a number of different routers in between well in this case we have one two three four five six hops between us and the destination so if there are an infinite number of hops that means that the destination is unreachable or that for some reason we're getting caught into some sort of loop so the Hops keep coming back to itself one another way that this can you can see this as I erase this is for instance we have A system that looks something like this and these are each routers so what might happen as I draw out all the connections is the route might go from here one hop to here and then instead of going to the destination it simply goes like this because this could be a valid way of getting to the router right we could hop here and then we could go over there but instead it hops and then this one sends it along this route so we move here and basically we create a loop in which the destination is never reachable now this could be because of some sort of poor uh routing table and what you would need to do is basically tell one of these routers that the destination goes over here the next term is What's called the cost this is the number of uh or these are the numbers rather that are associated with traveling from point A to point B generally this means Hops and several different links along the path the lower number of of hops the better we are so the cost would be how many hops total we need to travel from point A to point B generally speaking we're going to look at the lowest number of hops possible but there are some instances in which we could want to go more hops or have a higher cost through hops in order to save on something else for instance latency latency is the time it takes from a packet to go from one location to another so to give you an example of what I was just talking about sometimes we go route specific which means that it's going to choose this route because this is only two hops however let's say let's say that instead of traveling this let's say this was a dial-up connection right here and this was a broadband connection well obviously even though we have to go one two three four hops as opposed to three on this one we would want to take the four hops because the latency is going to be less and so the cost would be determined based not only in hops but on latency as well now convergence is the process of routers discovering the network structure has changed in this way it updates the routing tables to the knowledge of the networks so for instance if we have two different paths that a route could take it could either go like this or like this we would want to know if one of the connections had been severed and then this routing table would be updated to know don't go on this route instead go on that route the process of this happening is called convergence so although this module might have been short and a brief overview of routing we went over some key things first of all we talked about a router this is the device that generally allows us to connect our Lan out to a Wan it does this by operating on layer 3 of The OSI model which again is responsible for IP addresses as opposed to switches which work with Mac addresses and therefore operate on layer 2. we also talked about how a router functions in this case we talked about the fact that a router has what's called a routing table which can sometimes be called an ARP table the ARP table tells it where an IP address goes to get to a specific place so it Maps basic IPS to Mac addresses and then the routing table would say how many routes you take to get to a specific node on the network we also looked at static routing which is manually updating the routing table so that way you can tell it where to go we also talked about some key terms including hop counts which would be like the number of places we're going to go if we're going to take a trip this would be for instance the miles we looked at the cost which basically means we're going to take several things into consideration when determining our trip for instance if one has a highway whereas the other are a bunch of local roads with stop lights then even though it might be more miles to go on the Highway we're going to go there as opposed to this one with the stop lights because we know we're getting there faster finally convergence is keeping all these routing tables up to date that way we know which route is the most effective at any one time in the next module I'm going to talk more about how all this works in Dynamic routing and the protocols that are involved with it [Music] thank you welcome to module 8 lesson 3A on routing metrics or if you're in the UK routing metrics so this is a little bit esoteric in as much as you're better off configuring routing and playing with this and doing Hands-On labs which you don't do for the content Network plus but if you're doing a CCNA exam for Cisco for example you'd actually have examples where you could see this and been affected as you configure the different routing protocols and add more hops or other devices but we'll do our best we're going to look at routing metrics the MTU metric costs latency load reliability so routing metrics and tables on a router and it's actually the same for servers as well and the writing table can contain a field known as the metric now a metric is a value and that value can be made from a number of different factors depending on the route the routing protocol this is used by the router when it runs a mathematical algorithm to work out the best path to get from a which will be the local router 2B which is the remote router now I issue the show IP routes on a router in the image here and I just highlighted MD if you did look at the table there is short for eigrp on Cisco routing tables it'd be different if you're using Juniper or a different device but just for your information the different numbers there are the routing metrics the ergrp is calculated based upon the location of the different networks which are 34 uh 4.4.4.4 the 23 Network 24 and the 12 Network don't worry too much about that but I just wanted to show you that you can actually see it in a routing table and the number 90 before the the routing metric there is the administrative distance that um is is allocated to the protocol and for ergrp it's um 90 internally ergrp so if a router has different routes to the same network the routing metric helps the router decide which of these routes to choose because you could have 30 40 50 plus ways to get from A to B and the writing table will just be too big and the router would crash so it uses the best path and inserts the best path in the routing table all right each writing protocol uses a different metric I think you probably need an overview just for the network Plus so we've got two routers a router one and a router 11 between these two routers you've got nine other routers that connect to different Networks and you can see the different routers there path x y and z are the different paths in order to get to router 11 and of course you could make it more complicated by connecting all of the routers in between the paths which may well be the case so you want to get from router 1 to router 11 and there's three different paths to choose from sake of convenience as I said x y and z are the different path names writing protocols will choose a route with the lowest metric now if we use rip routing information protocol it only uses hop count it doesn't care about the speed of the link or if the Link's reliable or anything like that it's um a fairly old writing protocol and it was built for quite small networks because all networks were small at the time and so you can see there that there's uh one path has got three hops one has got one two three four hops in the middle if you're not counting the um source and destination the other has two routers nine and ten so that's going to be the shortest amount of hops two hops four or three so if rip chooses the route between router 1 and 11 it will choose the best path as path X it's got the lowest top count now I've introduced a problem here I've actually shown you the speed of the links and the speed of path X is only 56k which is a crazy slow when you compare it to path Y which is one Meg however rip won't understand this now you can configure it and and do extra configurations to um force it to take path y but by default it um it won't it won't use path y because the volt counts so different routes and protocols use different metrics and since the link speed affects the throughput writing protocols such as ergrp which is an advanced writing protocol take into account now it can take into account Cisco's version of vrgrp only uses two of the possible values um that um are usable Within ergrp and Cisco have their own version of ergrp now considering now ergb ergrp can actually use five but we've only listed the two used by Cisco devices here which are bandwidth and delay now considering the link speeds path Y is better because we want to take the faster um route there routine can be based on the following factors the MTU the costs cost latency administrative distance shortest path bridging uh the MTU um is one factor as I've mentioned stands for maximum transmission unit this is the largest size of the packet that can be transmitted across the link without that packet being fragmented fragmented means it gets chopped into different sizes and numbered sent and then reassembled on the other side of the link and obviously this can introduce the scope for errors and obviously there's delay while this fragmentation takes place thank you also overhead involved because of the acknowledgments each packet is sent and received as it goes along and it could be requested to be re-transmitted also largest packet you can send by an Ethernet Network because of the way the technology is designed is a 1500 byte now cost I actually did an output here of a router running ospf or an interface running ospf here and you can see the other information is irrelevant for our purposes but the cost has been allocated as 64. different interface speeds are given different costs by ospf total cost so this link and the other link and all the other links between and the hosts are added up together and then the best cast which is the lowest one is installed into the routing table and the other costs um can be put into the topology table for use if the best path goes down so you can have second best third best and so on a router protocol can also use delay or latency as a metric delay refers to the delay of the links across the route so is there any delays to the packets been sent and received a load I've actually issued a show interfaces serial zero slash one on this router and you can see some of the metrics that are allocated to this particular interface the mtus 1500 the bandwidth is 1544 so one Meg delay and twenty thousand millisecs a reliability 255 out of 255 is the best it means um it's very reliable and that if there's problems then the number goes down like 10 out of two five five is very bad the transmission load is low it's the lowest one out of two five five receive load is one out of two five five which is an arbitrary value so load is the measure of traffic consuming the links we don't want our package to be traveling along a path with high traffic so the past with the lowest load would be the best path if we're using load as a metric of course reliability is in there also which I've discussed we want to take into consideration the reliability of the path reliability metric has a value that denotes a number of times any of the following occurs the link goes down or had errors at a certain period of time the router protocol may use the following one metric as in rip multiple link characteristics to calculate a metric for example ergrp which is bandwidth and delay of the line ergp uses characteristics to calculate a metric for best path I've actually done a output of a Cisco router here for ergrp and you can see the different metrics here some won't be used you can actually affect this if you want in the configuration normally best to speak to a Cisco engineer before you do this so some of the delay characteristics are delay bandwidth reliability load and you can see others in there but again it's bandwidth And Delay the line is usually used uh summary so far we've covered routing metrics the MTU metric costs uh latency load reliability so that's all we need to know for now thanks for watching [Music] welcome to module 8 lesson 3B routing tables another hard one to put in perspective if we don't configure live routers but we'll do our best we're going to look at routing the routing table static routes and a static route example and dynamic routing protocols only an overview really and then an example and physically connected Networks so routing is the process of sending a packet from a source Network to a destination in another Network we actually have to differentiate between routing and packet switching writing is a process where the router actually decides the best route to get from A to Z and then switching in the in the context of sending IP packets is actually pushing the packet out of the correct interface I just want to do highlight the difference between the two and obviously we're looking at Network plus level stuff here so there's two aspects determining the optimal route which is the routing part and then pushing the packet through the network which is the switching part so routes are based on networks we don't really um we don't want to concern ourselves with host on networks because if you can imagine even an Enterprise Network for some large company could have thousands of hosts it'd be pointless every router having thousands of hosts listed so what it wants to do is focus on Networks and then it will then switch the packet to the correct Network and another router and then finally the host address in the Mac part of the address will be taken care of by the Lan switches so a route is not based on the host because the packets are routed through the networks it doesn't use the physical Mac address of the hosts so here's the example we've got a a few different I've shrunk down each switch would have it could have a 12 or 24 host connected but I've just added one and you can see we've got three different networks listed here the 192 a 10 and a 172 Network so the MAC address of the destination host is only used for the final delivery so the switch if these are layer 2 switches which are my examples they are it won't understand the IP address portion of the packet because we're looking inside the frame and it will match the MAC address to the correct port and then deliver the frame to that particular Port this is what our switches are concerned with whereas all the routing between the three routers in the diagram here they're concerned with which network or which Port which network is connected to of the router so the switch down here on the right if you issue a show Mac address table on a Cisco switch at least you'll see a map in and you'll see which Mac address and each one's unique is connected to which physical ports and this particular one they're all in the same VLAN because we're not worried about um into VLAN any any VLAN stuff here so gigabit zero slash two zero slash two zero slash two and fast ethernet zero slash one if you see more than one host connected to one port it means it's a trunk and it's connected to another switch somebody somewhere so this switch down here would be connected to another switch via a gigabit Ethernet port and it's learned a few host addresses that are connected to that all right so when we send packets out to the internet the following is true the routers have a database of routes stored in a table called a routing table it could actually be a database consisting of one route or just connected routes depends how we configure stuff really the writers use this information in the writing tables and they make a decision based upon the next hop this is what routers all do they send a packet to the next hop unless they are the the last hop in the journey so there's a routing table here you can see uh there's a network been learned and if I just put the text here the routing table contains the following the network ID here the network is three zero zero zero and it's actually found a host on this network destination Network address and subnet mask I'm not sure how this is been configured because I pulled this one off the um off the internet you can actually see at the bottom 10 10 23 0 is a network found by ospf and it will have the next top and Gateway so if we go to the bottom 10 10 23 0 110 is the administrative distance for rspf 20 is the cost and it's been learned via the address 10 10 12.2 which will be another router interface somewhere connected it was actually learned one minute and 17 seconds ago via the fast ethernet 0 0 interface all right so these the router has enough information that if it wants to send any packets to any host on the 10 10 23 Network it knows where to send it and it also knows how fresh that route is all right the metric metrics used to decide which route is to be taken if if multiple routes exist for a given destination Network so we can see some metrics here in fact um squared in the yellow highlighting you can see two routes have been learned to the same network the reason is the metric is exactly the same so it must be exactly the same cost to reach the destination via two different IP addresses one seven two twenty four one two two and one seven two twenty four one three four so as long as the costs are the same then ergrp is configured to load balance over those I think with um Cisco ergrp automatically load balances over up to four links and you can change that value up to 16. but this could change depending on your platform all right so the administrative distance when a router's right running two roads right on protocols such as rip and SPF and everything else is equal so for example rip and SPF it will use the ad administrative distance to determine which route to choose I've configured uh two routers up here just connected by a gigabit zero and zero slash one the top Network for the top link is 192. the bot and it's using rip the bottom is rspf and it's 172. and at the end we have another Network a Ted Network that is advertised via rip and ospf so rip I know the administrative distance is 120 ospf is 110 so routes to get from router 0 to the 10 Network should use ospf and if the ospf network goes down or the interface is really no SPF then the rip Network could be chosen this is a part of the output from a show ospf you can see 120 is the ad one is how many hops and under the 810 is the ad Slash 2 is the cost because rspf uses a cost not a hop value so it's the um the calculation is used looking at the um speed of the link is put into a formula and each link between source and destination is added to the cast so the cost is only two which is the gigabit Ethernet speed there and it'll be the speed of the interface that the 10 networks connected to so if if I try and Trace traffic going from router 0 to the 10 Network you can see it's traced and it's used the next hop address of 172.16.1.2 which is the gigabit uh zero slash one of router one and so that's basically the preferred path if for some reason that path went down it would start using the next best a next best ad which is Rip writing table writing information is populated through a few different means it can be a connected route actually a static route I I suppose I said connected there or a dynamic routing protocol what you can figure depends on your network if it's a tiny little Network or if it's in a remote office somewhere then you probably use a static route to just send all traffic to the next top router so this is the show IP route and I've highlighted in red the connected routes for router 0. it's a 17216 another 192.1681 network is showing as C connected are in Cisco at least that's for it oh stands for ospf and L stands for local static route is a route that is manually added to a router by administrator so you can see here router 1 on the left has got a default static route which you can recognize it because it's all zeros I'll give you an example in a moment if router 1 receives traffic destined to any network other than a local one are you one that's connected it should really know where to send that traffic if there's no entry listed then it by default routers will drop the packets since R2 is the next hop for router want to reach the internet what we can basically do is put a static route on router 1 saying send any traffic to any network over to R2 and let R2 worry about where to send it when our one receives the traffic for a network it's not available it will now send it out of its interface using the default static routes I've actually configured a static route here on a Cisco router iprout000 and then zero zero zero zero so any and IP address and any network go out to our gigabit Ethernet interface instead of g00 I could have put an IP address for the next top router as long as the router knows how to get there and for the R2 you can do the same thing you could have a static route as long as you know your next hop which would be your ISP router let your ISP take care of any routing decisions all right Dynamic routing practicals this is a routing protocol that dynamically builds routing information such as the following the network the next harp and it will build a topology table and from the topology table it will choose the best route to put in the routing table and the topology table can supply second third and fourth best routes and so on static routing does not do well in large networks because you would have to manually add 5 10 15 20 routes per router so you can imagine you're going to have a lot of work there if you decide to change the IP address and or even add one device so you don't want your routers to automatically learn the routes update any changes without you having to worry about it and this is where routing protocols make our life a lot easier once you've configured which networks you want to advertise then depending on which protocol you're using and the writing protocol will go ahead and run on automatic settings unless you change the settings for whatever reason the routers use the router protocols to learn about available routes to build a routing table and the routing protocol communicates with the same router protocol on another router you can't have rip on one router communicating with rspf on the other because they work in entirely different ways and use different protocols and ports to um send their information so this information is placed in the writing table so as an example here router one two and three you've got some different networks connected a pc1's default gateway because PCS won't do the routing will always be router one you'll just send all traffic to whatever the IP address is of the router there normally in In fairness the PC is connected to a switch and then a router this is just a simplified diagram so if router one has two routes to the internet then it will choose the best one depending on the routing protocol unless you've changed the settings you can obviously manipulate things if rip has been used then it will choose a hop count and it will choose the lowest top count so it will be router 1 to router 3. even though it's 128k the link there if rspf is being used um then it will choose R2 that might not be correct actually if I look at the diagram you'd have to add up the um speed of the links but the speed between router 2 and router 3 is being put as 128k so um that isn't quite correct say you've got a one Meg link between router one and two and then two and three then ospf should choose the um that link even though it's more hops because it's only looking at the costs so Dynamic router protocol also allows a router to reroute around a fellow link and this is where the topology table will come in it will have a um ability or most advanced protocols do to have some backup routes in the topology table that will quickly take over uh physically connected networks routers interfaces physically connected to a network it obviously knows how to reach that Network since r1's interface is directly connected to these networks it already knows how to reach them all right so we've covered routing just in an overview the routing table static routes an example of a static route autonomic routing protocols as an example and then physically connected Networks now your physically connected networks you don't have to advertise but obviously if you want traffic to be able to reach that Network then you're going to need to add a dynamic or static route but that's all for now thanks for watching [Music] local area networks Dynamic routing and protocols so in the previous module we discussed what a router is and how it functions and we discussed static routing which is the process of manually creating a routing table so in this module we're going to Define in more depth Dynamic routing which is what allows routing just like with DHCP and IP addresses to be dynamically up kept which is going to allow for a much more flexible Network now although this title of this entire lesson is local area networks in some ways we could extend this to wide area Networks so we're going to talk about Dynamic routing and then we're going to talk about two different types of dynamic routing these are distant vector and Link State now we sort of alluded to the difference between these in the previous module when I was discussing Hops and simply relying on the number of hops to get from one place to the other versus looking at for instance if one link was a dial-up or Broadband or if the link was even shut down completely and so there are two different types of protocol sets we're going to look at there are distant Vector protocols these are the protocols that allow distant Vector routing and then there are link State protocols you'll see them listed here and we'll talk about each one in depth and if the acronyms are already starting to freak you out don't worry about it what we want to do is just know which ones are distance vector and which ones are link state so as you can tell if you can remember that these two are link State you'll be fine for the network plus exam which again is multiple choice and will ask you to recognize it but we'll go over them in a little more depth than that so Dynamic routing uses a series of protocols to establish the routing table as opposed to the route add command all of the routers pass information about themselves along to the other routers and they use this information to establish a routing table based on certain specifics of the other routers now there are two different types of protocols that are used like I just mentioned there are the distance Vector protocols which in some ways are older and the link State protocols which are newer the reason being that distance vector looks just at the number of miles we have to travel and the link state also looks at the traffic so it can tell us if although we'll have to go further miles it's going to be quicker based on traffic just like our GPS system so let's talk about distance Vector first in distance Vector routing the routers on the network are only aware of the routers that they are directly connected to so if this is one router let's call this router one and there's a router two a router three and a router four router 1 is only aware of routers two and three so these routers don't know anything about the rest of the routers on the network unless of course they're directly linked now they can share route information with these directly connected routers but the flow of communication is limited as a result the spaces between distance Vector routers are known as we just talked about this hops now each router along these paths represent a hop for example a network with a five distance Vector routers has four hops from the first to last router if we have one two three four five routers there's one two three four hops it's also important to notice that convergence that's the updating of all of the information to the router table is going to take longer with this set of protocols than with link state which we'll look at in a second this is because the routers don't have the knowledge of the entire network so it takes longer for them to become aware of a change in the network so there are four main distance Vector protocols that are still in use today the first one is called the routing information protocol or rip routing information protocol version 2 there's the Border Gateway protocol or bgp and finally the enhanced interior Gateway routing protocol or eigrp you see how these two sort of have some similar names in them and these two are obviously related rip or routing information protocol is limited to only 15 hops originally it required the information that updated every 30 seconds and on a small Network this wouldn't have been a problem but if we're talking about a very large Network which is where networks went there was going to be a large amount of traffic being sent between routers at any one time and so this became not very useful because of speed and also the protocol itself was just not very secure and it was very vulnerable to attacks and it didn't support authentication of any sort now remember we want something like authentication which would be a username and a password so I can make sure the router contacted me is the one that I wanted to talk with so rip 2 came out and this featured authentication so it added it for better security and it also was designed to reduce traffic flow but it only supported 15 hops because it had to be backwards compatible with the previous version and since the previous version was only 15 hops so was this one so again not very useful for very large intense networks such as the internet now bgp is often associated with the internet and the reason is because it can be used between internet gateway hosts as this name implies so it examines the routing table and decides what is the best route for data to travel based on the connections the distances and certain addresses now the enhanced interior Gateway routing protocol are eigrp draws upon information that its neighboring routers have so it would look at all the routers that it's a neighbor with now route is configured with eigrp would use that information to determine the best path for data all determined by what all these other routers know so that's one of the benefits is it went outside of itself so here's an example of basically distance Vector routing the router on the top left over here has no idea what's going on with the routers over here it can only make a routing table based on the routers it's connected to just like the one on the right can only make uh routing table based on the routers it's connected to therefore these two are unaware of each other's dis of each other's existence because they're not connected to each other now of course they can still communicate because there's probably a router some place that one of these is connected to that will connect them but you can see how this is going to make for a lot less efficient routing so unlike those distance Vector routers routers configured with link State Protocols are aware of every other router on the entire network they use each other to build an enormous Network map and then this network Mac is shared with each other unlike distance Vector link State routers will update with less frequency so there's less traffic on the network now if a change in the Network's topography occurs then they automatically update with each other and share the map with each other so instead of Simply updating at a certain interval of time they're going to update whenever there's a change now though this seems like link state has a better set of protocols link State routers also require a more powerful system components such as better Ram cetera then distance vector and that's why we still see distance Vector used quite a bit in some cases we don't need link state so it offers quicker convergence as a result of this automatically updating but this also means it needs more power so there are two protocols I want to go over with this the first is the open shortest path first or ospf and the second is the intermediate system to intermediate system protocol these are really similar and they both use a shortest path algorithm to determine the shortest way for the data to travel however we're generally going to see this one the OS PF on medium networks and Isis on larger Networks another benefit of this is because it knows all of the routers on the network it doesn't just think about distance it also looks at what type of connections we have it looks at the state of the links and therefore it can make give you in some cases the best route available not just based on the number of hops but on a lot of different factors so here we can see what a link State protocol might look like the two different groups aren't connected directly however they're both aware of the entire network layout as you can see if we imagine that this was a map inside of the router and then they can then share that Network layout with all of their other routers in this way they create a massive Network and massive routing map on their Network and can communicate much more efficiently and quickly so we've just talked about Dynamic routing which means basically that the routers builds their own network map or routing table this is much more efficient than static routing we also compare distance Vector to link State again distance Vector is focused very much on Hops and isn't aware of all of the devices on the network only direct connections link State on the other hand looks at other features so for instance traffic latency Etc and has a huge Network map of course the downside is that distance Vector is going to be a lot more efficient with the resources it has in the router than link state which requires uh perhaps better or more powerful system components we also finally talked about the different protocols rip rip version 2 bgp and eigrp were our disinspectors and our two link States again ospf is for medium Networks and Isis or Isis is for larger Networks we still see all of these used but these are newer perhaps a faster at convergence although perhaps not the most ideal for our Network or necessary for the network we have so now that we've talked about switching and routing I want to talk about something which is a little not so much complex but allows for more organization within our Network which is called vlans or virtual lands [Music] welcome to module 8 lesson 4A igp and EGP all right so we're going to look uh this is an overview really to put things in context a dynamic router protocols interior Gateway protocols autonomous systems bgp in brief obviously how the protocol works much so we can classify Dynamic writing protocols into interior uh and exterior the interior protocols these are the ones that we'll be using mostly As Network Engineers on a day-to-day basis unless we end up working for an ISP an internet service provider so in order to understand what we mean by the inside of a network we actually need to understand the term autonomous system which we generally shorten as an m2as so an AES is one or more networks that are governed by a single Administration so it could be a company Network or a large company Network and you can see here we have um three different asses now these as could actually all belong to the same company and inside you've got a different administrative domains for example the large Cloud as200 could all be running ospf and you could have bought a company on the top left there that um is running ergrp or just has a different set of administrative principle principles and roles in this particular example you can see as100 on the top left and as300 on the top right are actually isps these are internet service providers so um even though it says here that the as within is under the control of a single Authority you could have various teams managing different parts of the network however it's all under the same administrative control as is actually defined in the one of the rfcs 1930 if you wanted to Google that but it'd probably be a fairly long and boring read I think according to the definition of the as it's a set of routers under a single technical Administration uses an igp interior Gateway protocol and common metrics to Route packets within the as you would you generally use an exterior Gateway protocol an EGP to Route package to other autonomous systems The ROC says that the as a single and clearly defined routing policy which makes sense if your company is running the administration now routers within an AES use an igp which I've already said so here's um an image from Microsoft's tech net you can see there's two different autonomous systems here they're running an igp and is here we Gateway protocol doing all their ospf routing whatever they need to do and then in order to communicate with another autonomous system it's running in the EGP between the two border routers there you can further and divide igps into distance Vector link state or hybrid some of the common ones are rip or rip version two ospf is an advanced writing protocol Isis ergrp is a hybrid which is uses parts of the distance vector and part of the link state igrp is um pretty redundant now to be honest it's not very rarely used because of its aging it's not very flexible at all uh exterior Gateway protocol is a routing protocol used to route between a s's which we've already mentioned if you're going to route between autonomous systems it's referred to as inter as routing so an example is bgp which is mentioned in the syllabus is used for inter as routing so it's a route between as1 2 and 3 here we've got an exterior Gateway routing protocol there is actually a writing protocol called interior bgp which you can use to Route within an autonomous system and I think that's mentioned in the syllabus in any detail but um bgp is used to route between autonomous systems exterior bgp now each as is actually given a unique number you have to apply for these numbers to your service provider or your internet registry whoever that may be and as I said I've already said this it needs to be a unique Asm and the ASN is a actually supplied by the internet assigned numbers Authority and they'll split the numbers between whoever governs the numbers within your country uh all organizations within the network don't need ASN the Network that has a single connection to an ISP and a single prefix which is a subnet mask doesn't need the ASM because the prefix of that network is managed by the internet service provider so you may not actually need to worry about any of the exterior routing you could be really low SPF all through your network send your traffic to your internet service provider and let that let them take care of any exterior routing bgp exterior Gateway protocol and it routes packets between the Asus which I've already said here is an example of some different ases and on the bottom you've got as1 which has the um prefix 192.020 and the subnet mask of Slash 24. 24 bits according to the RFC and bgp is an inter-autonomous system router protocol it actually uses TCP so it uses a reliable transport method as opposed to other protocols it listens on TC Port what TCP Port 179 and you can see we've caught a captured a bgp message with a a packet capture program looks like Wireshark there's an open message and you can see the destination Port there is 179 and it's using TCP current version is four if you could look further down inside the bgp packet it says version four that's the current version in use today all right so CompTIA they actually list it as a hybrid protocol I'm not sure why they do that it's a path Vector routing protocol so you can see the paths here as1 at the bottom is sending the nlris network layer reachability information I.E how to get to that particular Network and prefix router 3 appends its path which is as3 and then when the um network 192020 is sent to as5 it's appended with the paths four three and one as a reply is sent the different paths are removed so as4 will remove path four and send it to three we'll remove three and back over to one all right so we've covered an overview of dynamic protocols interior routing protocols what an as is bgp that's all for now thanks for watching [Music] log into module 8 lesson 4B routing loops but look at what a writing loop is and distance Vector writing protocols splitter Eisen and poison reverse which are there a couple of the solutions to prevent routing loops on a network layer 3 loops so writing Loop is a network problem where a pucky gets routed between two or more routers endlessly now this is a different solution to layer 2 Loops where we have a spanning tree protocol and some Advanced versions of that that uh there to stop layer 2 packet circulated because Layer Two packets don't have a time to live value so this happens when the writing table has incorrect information as we know during the writing process routers forward packets to various destinations these are based on the entries in the routing table now if one of these entries is incorrect for example a network goes down then a routing Loop can occur so here's an example I'll go into more detail in a bit but for today's advertising 192.168.20 which advertises out of both interfaces there it goes to router BM router C both of which advertise to router a now rights array unfortunately has two ways to send the packet to router um or to to paths to see uh 192.16820 which isn't necessarily a problem however what router a does advertised the fact that it knows how to get to that Network to router C to router B which then forwards it to router D now router D is hearing from other routers that they know or they have a route to get to 192.1682.0 now if that Network goes down router d will be sending packets to that Network either to router C or router B because it's heard from those routers that it knows how to reach that Network so this is how our writing Loop can um cause havoc on your network so go go to a bit more detail with another example here obviously have a detrimental effect increases packet loss utilization of the links CPU utilization on your routers because it has to process every time the packet's received so in distance Vector protocols slow convergence causes routing Loops this is when other parts of the network are stabilizing their routing tables slower than other parts of the network any change in the network is updated in the writing tables so during the process the routing tables have inconsistent entries due to slow convergence this could be due to bandwidth or pros and processing speeds on your router the network is said to have converged when all writing tables are consistent so this means every router's got the same picture of the network and they all agree on which networks are where so here we've got router C advertising the 1011 Network when the net was converged all routers will agree that that Network exists and they will agree on how to reach that Network so a will send it out of the right hand interface B out to the right hand interface and then C is directly connected now if this network goes down or the interface goes down relative c will remove that route to the network from his writing table but before this update is the center out to be router B sends a periodic update to router C saying it knows how to reach the 10110 Network so this update makes for how to c think that router B has an alternative path to get there obviously through some of the series of routers it doesn't uh have a picture of the entire network and well it's got this directly connected Network and it believes what it has from other routers so it will mark this uh route to get to the 10110 Network as reachable through router B a periodic update from RTC will contain that Network which we've already said router B assumes it knows how to reach that Network mentioned in the update now when router B receives a packet destined to the 10110 Network it will forward it to router C when Route 60 receives the packet it sends it back to router B and this is where the loop is happening so unlike switching Loops the in writing like the packet will last until the time to live value which is TTL in the packet header reaches zero so you can see the time to live fields in this particular packet here which is a bgp packet capture once the time to live value reaches zero the routers then drop that packet and disinfected protocols we've got a couple of solutions splitterizing and poison reverse so this is split Horizon the rule is that if an interface learns a particular route it doesn't advertise that route back out of the same interface now this causes problems when you come to configure a hub and spoke Network and there's ways around it which we're not going to cover here with ergrp and ospf in particular you can change this rule or turn this rule off and set of ways to get around it so routing works so router a learns about rata C from router B what it won't do then is advertise the network back out of the same interface to router B because this would breach the split Horizon Rule and basically route and the networks attached to router C can be reached via B so it doesn't need to be re-advertised back to router B and cause confusion poison reverses a form of split Horizon it uses a method to use um known as route posing angle poison reverse it allows the router to set a distance to the network as Infinity this is for the um how many hops for example in rip this allows the network to converge so perhaps you've had some instability the network attached to router E network 5 has gone down so router e will quickly advertise that with an infinite distance which is known as rat poisoning so I've looked at Loops distance Vector routing protocols bit Horizon poison reverse that's all for now thanks for watching [Music] foreign networks vlans and sohos so we finished talking about switching and routing how networks communicate with one another and so now we want to talk about two other terms that we see a lot when we talk about local area networks and they're important to know for the network plus exam the first is called VLAN or virtual local area network it has to do with segmenting a physical local area network into two or more virtual or logical local area networks and we're also going to discuss what they do and how we Define memberships in vlans since this is not a physical distinction but a logical one we're also going to discuss a Soho Network also called a small office home office Network we've probably seen this term in the past because we deal with it when we talk about Soho routers which are those routers like the d-links and the Linksys that you have at your home that allow you to get for instance wireless access although these provide many different things they're distinct from a regular router a Soho router because a regular router just does routing whereas a Soho router does several different things now that's an example of why a small office home office is so such an important term when it comes to network Plus so virtual local area networks or vlans are a type of local area network configuration they're actually somewhat of a misnomer though the word virtual is really the focus of the name they're really more segmented than virtual VLAN can be described or defined as a group of computers that are connected to one another although they function as though they are on different networks even though they sometimes aren't so the computers that are segmented together are usually ones that are in a same Department as the others for example we might have an office building with four floors and the encounting employees could be on every floor a VLAN would allow them to all be connected to one another even though they're really sort of sharing the network with every other department in other words if we had the accountants and then let's say the managers they would all be connected to the same physical Network in the building but we could segment them into separate virtual local area networks so that way they can communicate with one another and other folks can't communicate with them they would therefore think that they were connected physically to one another or all plugged into the same switch even though were you really using four different switches one for each floor now there's some very clear benefits to having VLAN set up first the security is increased this is because when we segment a network there are virtual boundaries and that makes attacking the entire network very unlikely it also makes sure that accounting people are going to have a harder time getting into the management people's information so again even though they're physically connected all the same we're giving them a virtual segmentation so that they are separate and therefore it's a slightly more secure they also increase the performance by freeing up bandwidth and reducing and splitting up traffic from the network if accounting for instance uses a lot of bandwidth and management doesn't well we don't want management to suffer because accounting is using QuickBooks and the servers so much therefore by segmenting it we can make sure all of the traffic that accounting is using is staying on their segment and management performance doesn't suffer as a result we can also group users that often communicate and share data and so this network becomes far more organized this is not just from security and performance perspectives organization is just from a logistical perspective as well I can put someone in a VLAN and automatically they're going to have all the benefits that come with being in that segmented area independent of their physical location finally it also makes the administrator's job a lot more easier because when everything is segmented up things become easier to deal with I don't have to create a specific set of policies or security for one individual when I can simply uh put them into a VLAN and let it all sort of work itself out so here's an example of what a VLAN might look like as you can see there are four floors to the building with computers on each of them and the computers are all connected to the same network I very much simplified this in fact we would probably have uh switch on every floor remember this would be called the idfs and then they would all come together like we see here in one Central MDF but for all intensive purposes they're all connected to the same physical Network however we only want the accounting employees to share data with themselves not with the graphic designers or the marketing folks and we want them to have their own segmented Network as well so with VLAN we can actually segment out the counting folks into their own virtual Network even though they're on the same physical Network the same could go for the graphic design folks and the marketing folks they're all split into segments with similar employees and we would actually give these vlans numbers for instance VLAN 1 2 and three now there are three different ways that VLAN membership can be assigned a membership is a way that the device is assigned to that specific VLAN for instance the one two or three that we just mentioned the first method involves protocol-based vlans in this way computers are assigned to vlans using networking protocols that are in place such as the IP address the IP number is only used to determine the membership but has nothing to do with the routing of the VLAN Network so for instance we could say all IP addresses from 1 to 100 are on a specific VLAN and all the ones from 101 to 200 are in another another thing we can do is what's called Port based vlans this requires that ports on the network switch are assigned to specific vlans so as you saw previously we had uh accounting and marketing and Graphics all in sort of different um physical locations but they were all plugged up to a central switch so what we would say is for instance any computers plugged up to supports one through three are in VLAN one and the ports plugged up to four and five or in two and six and seven are three now remember a lot of switches can have perhaps 200 ports so this can get a little complex finally there's mac address based vlans in this way you've heard of the physical address and when you know that we can use this to actually filter out um using a what's called an ACL or Access Control lists certain Mac addresses from a wireless access point well it works the same way with a VLAN depending on the Mac address of the computer that is being connected it will automatically place it into a specific VLAN of course the benefit with this is because the MAC address is the physical address of the computer and is always hardwired onto that computer I can move the computer into any different port and it can get any different IP address and it'll always remain in the same virtual local area network now the other term we want to talk about is a Soho Network or a small office home office Network this is generally speaking as the name implies a smaller home office Network that serves between one to ten users on the network now you can have more users or less users although I guess you wouldn't have less users than one but generally speaking it's really going to designate a very small Network although they're smaller in physical size and generally smaller than the number of users they're going to accommodate the network in the same sort of way meaning we're going to use some of the same protocols and devices they're just going to be built differently because they don't need to be as powerful so for instance here is a small office home office Network you have two PCS in it perhaps I have one in the living room or one in the bedroom and one in my home office and maybe even we have a laptop as well so maybe we have three different computers ones for the kids one's for my wife and one's for me now we have what's called a small office home office router now it's called just a router to many of us but really this is a small office home office router because it does several things it has a built-in DHCP server for a lot of us it also is Wireless so it's a wireless access point or WAP it's also has uh plugs on the back so in some ways it acts as a switch for us although that's built into a router so I'm not going to write that separately it does something called Network address translation which allows the IP address coming from our internet service provider on our modem which might be let's say 126.43.17.3 to be shared among three different uh internal devices so that way when information comes in from the internet it knows which device to send it out to and also does a couple other things for instance it might have a firewall and to do some other stuff we've mentioned as well no matter and it might even allow for vlans actually but no matter you can see that this one device is taking on several devices that we've talked about previously this was your only uh experience with a router and you might think all routers operate this way in fact they don't we just call it a router because that's probably the most important function it does which allows us to get out to the network but there's not floors and floors and floors of stuff going on here and this router wouldn't do very well is because it's not built to if I tried plugging a hundred computers up to it so the real important thing here is as you go forward in your career you'll probably be seeing more and more of this and if you're going to be supporting homes or really small businesses then you want to know that perhaps they don't need a separate switch and router they just need one device that being said if a company is growing really fast perhaps they need to purchase a separate switch that then plugs into the router the switch therefore can help work with traffic internally of the network and the router will help get the information out onto the network but it's important again to realize that even though this is a small office home office or Soho that's not the area or the geographic location remember that's just the name of this type of network that it's going to have all the same principles apply it's just the devices might be smaller and less able to handle a lot of people so we've talked about uh virtual local area network which is basically segmenting a lan or local area network into several logical partitions but physically everything is exactly the same we talked about how we do the memberships for these we can do it based on the port it's plugged into we can also do it based on the Mac address or based on the protocol which in some ways would be linked to the IP address finally we talked about a Soho Network or small office home office Network which the real reason we want to know that is because the devices are going to be less powerful okay and they're going to sort of converge meaning that we're going to have a wireless access point that's also a router that's also a DHCP server whereas in a large Network we would separate all of this out so that's sort of finishes our discussion on local area networks and lands the next lesson is going to talk about wide area networks or wans which we've already talked about slightly when dealing with routing but we're going to talk about that in a bit more depth vlans and drugs we'll be doing some Labs on this as we go through the course so don't worry um if it doesn't sink in straight away a VLAN is a virtual local area network so it's not something you can see by physically looking at the network you'd have to look at the configuration of the switches it defines a broadcast domain in the layer 2 Network so just the same as local area network using the switch the switch will forward broadcasts however if you have two vlans on a switch for example the one on the top right diagram there the broadcast will stop as far as the VLAN reason is you need a layer 3 device which is normally a router in order to send information from one network to another so virtual local area network for all intents and purposes it follows the same rule as a normal Network or subnet so you can separate broadcast domains even though it's on the same physical switch by configuring a layer 2. a VLAN is a logical division of switch ports so if you had 20 switch ports physically on the switch you could in theory have 20 different um devices each in its own VLAN you need a router to pass packets between vlans some switches actually come with a a writing module that you can insert which is a bit beyond CCNA level to be honest just for your own information so vlans can spun multiple physical switches so we've got switch one two and three here and you can see we've got a couple of different vlans configured best to have all hosts in the same VLAN on the same subnet that's all really wanted to say on that particular subject but it's just the best um idea no need for a variety to communicate if all the devices are all on the same VLAN some of the benefits or why would you bother logical separation just gives you better security helps with the broadcast issues if you do up on better utilization of your bandwidth Avila marking obviously it has to be some way if you're chopping your network into vlans for the VLAN to identify itself vendors use different approaches for example Cisco created ISL into switch link which is a proprietary for Cisco devices they've actually moved away from ISL now though many of their switches still support it and they moved on to IEEE standard 802.1q called frame tagging frame tagging inserts a 32-bit tag field into the original frame so concept of a native VLAN is something you should be familiar with as a Cisco engineer a native VLAN on Cisco devices certainly is all allocated to VLAN one by default all devices in a VLAN will be assigned to VLAN 1 unless you configure and then to be in a different VLAN so traffic on a VLAN on that on the native VLAN is not tagged it's not given the 802.1 Q tagging well the reason is it uh we have it is it allows the switch to communicate with the device that doesn't understand 802.1q it is a security risk which we'll cover later on vlr membership so you can assign VLAN devices or ports to a VLAN statically as a network administrator it can be dynamic based upon device Mac address switch ports are assigned to vlans and then devices plug into the physical ports access ports connect to network hosts a network hosts connect to access ports it works both way around that sentence if you want to connect to another switch and you're using multiple vlans then these connections are known as trunk ports so trunk ports uh will connect more than one VLAN which is connecting more than one VLAN together so a special Port type carries data from multiple vlans it can use ISL although that's pretty much been depreciated now so you shouldn't be looking at it for the CISCO exams at least frame tag in is transparent to end hosts so the tag is attached by the switch sent to another switch and before it reaches the end hosts the tag is actually removed trunkport modes we can manually set the interface to trunk with the command switch Port mode trunk trunk modes include on which is manually set the interface to trunk off you can tell it to never become a trunk Auto silently wait for a request to become a trunk desirable which means actively seek to become a trunk or no negotiate you'll cover these commands in detail when you come to do the CCNA I probably won't be doing um covering these commands and how to configure them for the primer configuring a VLAN you need to manually add the ports to vlans and you need to set your ports to trunk so here's a configuration I've just done one side because the configuration is the same for both switches I've created VLAN 5 in config mode by typing VLAN 5. I've given it a name called RND so you can name your vlans it probably makes it easy for you to manage interface fast ethernet zero slash one I've created switch Port access VLAN 5. so this is telling the port that it's a switch Port layer 2 and it and the device is belongs to VLAN file that's connected to it I've gone on to my fast ethernet 0-15 switchboard trunk encapsulation.1q to tell it what encapsulation to use that won't work on a 2960 switch because 2960 will only recognize.monkey and I've told it to become a trump port okay so you'll be labbing some of this up later on but for now that's the end thanks for listening [Music] wide area networks implementation and administration in the previous lesson we discussed local area networks or lands these were networks that were restricted to a specific single geographic location now in this lesson we're going to talk more about wide area networks or wans we're going to Define them and talk about how they compare to local area Networks so we're first going to define a Wan which we've talked about in general before and then we're going to identify some of the steps we would take to implement one uh specifically some of the things that make it different from a local area network or LAN finally we want to identify some of the administrative tasks that go along with or that challenge us as Wan administrators specifically backup and security so a Wan is a wide area network and though it functions very similarly to a lan it is different in that it's the way it's set up and the way it's connected when is uh Network that's not restricted to a single geographic location like a lan in fact it's often made up of multiple lands all linked into one big win and these lands can be across town from each other or even across the globe now we've talked about some other terms for instance can like a campus area network or city area network and a man or a metropolitan area network but all of these could be in some way shape or form are considered a Wan and of course the biggest win that's out there is the internet usually referred to as the cloud because on network diagrams a cloud is used to represent it now because of this Geographic distance lands are generally slower than lands because they have to as it makes sense travel a longer distance to deliver data just like if I sent a letter internationally it's going to take longer to get there than one across town or even across the country that being said newer Technologies such as fiber optics and etc etc are making Wan connections faster and therefore are connecting parts of the globe that have never really been connected before so here's an example of what a wide area network might look like let's say for example that a company had two branches one in New York and the one in Houston each of the branches has their own local area network here the one in New York and the one in Houston obviously these are simplified so imagine that instead of just two PCS on each there are maybe five thousand and instead of just one server maybe there are 20. but they each have their own switch to talk locally to one another through Mac addresses then there's a router on the edge of each Network that connects it out to the WAN or the internet of course the WAN if configured correctly can also connect these two lands as though they seem like they're in the same location just like their next door now we could set up our own Wan in other words we could have our own cables and wires running through uh from New York to Houston and that's going to get really expensive and so we've come up with Technologies to use the existing Wan that's out there I.E the internet in order to create secure connections between two locations without having to actually physically lay our own chords however the idea is the same we connect two lands through a Wan and this allows users in both locations to share data easily a great example of how this is deployed worldwide would be Banks or for instance American Express or chase you can buy something with your American Express card just about anywhere in the world and it still takes the money out of your bank or puts it onto your account almost instantaneously now the process of establishing a wide area network is really it can be quite complicated although it's gotten more and more simplified over the years so I'm just going to go over some of the basic steps and do it in a really simplified manner uh basically what you need to understand for Network plus a good way to start with the Implement implementation process to set up what we call a VPN or a virtual private Network so the name implies it's not actually a private Network that would be one in which I actually have a cord stretched across the country connecting one computer to another rather this is a virtual private Network so this is a type of Wan and what it does is it actually allows us to use the public Wan the internet and create a tunnel through it called a virtual private Network that then makes it seem like the two locations are right there next to each other the benefit of a VPN is that it makes it secure so once you basically install the settings you need to put in some administrative policies and rules so not just anyone can tap into your tunnel otherwise it wouldn't be very secure and there wouldn't be any point we also need to select certain users who are going to be able to get access to it and how we want to allow them to have these remote capabilities we'll talk about a VPN in a bit more detail and we've talked about it a bit in the past finally we have to add the user accounts to our local networks so that then they can communicate throughout uh the Wan this can be configured using either IP addresses or Mac addresses or domain names so just to go back over that again I create the VPN I give access to the users and then I connect those users to the network perhaps I connect them to the network from home perhaps from their own internet access at home or their own internet router but in some way I have to give them access and that generally involves some sort of special software or device and some sort of authentication such as a password or pin number now being the administrator for Awan can actually be pretty demanding because it's not restricted to a single location the job involves a lot more than being a land administrator because you might have a land that's all in New York but if I have a win I could have offices all over the world so the main tasks though are still the same they're just generally on a much larger scale in fact almost every task that both administrators would share is just larger in scale and just a little more difficult for the wan to admin so backups are just as important on a Wan as they are in a land if not more so because data loss of any kind is something that needs to be avoided it's the way an admin's job to be in charge of backups for the entire wide area network and make sure that everything goes well the actual process of backing up everything is virtually identical on both networks however with Wan it's much more difficult because as we said before lands span over two or more physical locations geographically and are grouping Lan networks together so we need to not only back up stuff at the individual Land locations but then we need to put all that together into one big huge backup of course one of the main differences we mentioned at the outset is speed and so when we're trying to back stuff up to a wan to the internet speed becomes an issue I can back something up really quickly if I plug it into the computer when I start going over the network that's a little slower and then when I start going over a Wan it's going to get a little bit slower too so full backups can take days depending on the size of the WAN and obviously the issue with that is if it takes days for me to back something up and I'm working on it then by the time it's backed up it's actually hasn't gotten the backup at all and so we have to deal with all sorts of stuff when we're doing this so as you can see here I generally might have some sort of off-site backup area that all the data would sort of Route into sometimes what we'll do is we'll actually back stuff onto a local backup and then the local backup will be backed up to a cloud backup or a Wan backup so we have to deal with space issues and we also have to deal with speed issues now when it comes to backups as you can imagine that's some pretty important data that's flying over the network and so I also need to make sure not only my backups but my entire network are secure and this is a massive job for the administrator of Rowan in fact generally when administrators don't do this they hire someone else to specifically focus on security again the big difference with Wan is that the network is not limited to a single location so there are many more points for Access for people who might have nefarious uh purposes to get into our Network this means the administrators not only controlling the security at each physical location but also the security of the entire network as a whole theoretically if an attacker were to infiltrate one of the lands it could infect the rest of the WAN so we have to have a lot of fault sort of safety measures in there as well it makes our job really difficult and we not only have to spread against these attacks but also the spread of attacks if one site gets infiltrated well I can't do anything about that at that point but I want to make sure all my other sites don't get infiltrated as well so here we see the same wind from earlier but unfortunately a virus has been sent by a hacker and it's making its way through the wan to the other land this is an example of something an admin would have to be diligent about in some ways what we want to do is create some sort of wall here so that way the virus or the logic bomb in this case couldn't make its way over and just got stuck and stayed in Houston while it's still a pretty bad scenario at least New York hasn't gotten infected so in this module I really briefly talked about a Wan or a wide area network remember a Wan is comprised of several lands that are connected over a geographic area in some cases we're going to connect them through the use of what's called a VPN well we have a VPN or a virtual private Network it creates a tunnel over the Internet which is our public switched Network or our public network and we create a private Network within that using all sorts of protocols we'll discuss so that way these two lands can communicate as though they are actually one Lan or they're right next to each other we also need to have user accounts so that way the users can't just not anyone can get onto a network they have to have a specific password authentication Etc and those users also have to have access somehow whether that's through the internet or they actually are physically connected through our land site we also talked about some of the administrative tasks that can be difficult for lands specifically backup where we're dealing not only with speed but also with amount of data and we talked about security we're not just stopping intrusions but we also need to limit the spread of an attack [Music] wide area networks Wan transmission technologies so in the last module we talked very uh briefly and in an overview sense about the implementation and administration of wide area networks now the reason we didn't get into too much detail is because it gets quite complicated when we talk not only about connecting computers together in a local area network but in a wide area network and as a result the Technologies become more and more complex and just like we have people who specialize in lands they're people who specialize in lands since the purpose of network plus is to give you an overview of all the stuff we just want to get you familiar with certain terms so in case you were to come across them you would sort of know where to look or what to start with when you look for more information now in this module we're going to talk a little more specifically about Wan transmission techniques again we're going to look at this from a mile high view so the techniques then the transmission technologies we're going to talk about are specifically ISDN which you might remember if you've been around for a while it's mostly been supplanted by DSL and cable to this uh nowadays as actually you have most of these Technologies but some of these are still around and you probably have heard of them so ISDN is the first we're going to talk about we're also going to talk about t carrier and if you've ever seen the term a T1 or T3 line that's what this is referring to we're going to talk about Sonet which is responsible for a different type of classification it's also using some Optics which is why it's a bit faster and required a completely different form of rating the cabling and the speeds and then we're going to look at some technologies that allow the data to transmit over this stuff these T carrier and sonets including x25 and frame relay x25 was supplanted by frame relay and ATM which is not the thing you put your card into to get money out of but rather a technology of protocol that allows us to communicate over when Networks so the first one we're going to talk about here is the integrated Services digital Network or ISDN now uh the ISDN is very high speed but it's also high cost and the reason for that is because in order to use ISDN a special phone line is required to set it up now the line is paid for monthly just like with any phone line and this is where the high costs come in because the service is pretty expensive to pay for every month in order to set up a connection the phone line has to dial the address of the receiving computer very similar to the process of calling a phone on the other end and once the connection is established you can drop it by just hanging it up so if we were to consider this for instance to be our um uh ISDN line you would notice there is sort of a box here and that's because we need a special box to allow the istn to communicate and it would then communicate onto the other side to the ISP now what's interesting here is this is actually a plain old telephone system line or uh by the way Plano telephone system or pstn public switch telephone Network so this is using uh old telephone technology but the difference is instead of using the one that's already been installed into your home or to your office it's actually another one that has to be laid down which is how it's different from DSL now there are actually two different types of ISDN we've talked about these in a plus as well one is the Bri and the other is PRI Bri by the way stands for basic rate interface and this one stands for primary rate interface primary is a bit faster but it's also a little bit more expensive now there are certain speeds these operate at generally 64 kilobits per second or 128 kilobits per second again that's pretty slow when we compare it to modern day DSL or modern day cable Technologies but this was a dedicated line specifically from you to uh the ISP which is the reason why even though it was a little less fast it was still used although nowadays we don't see it used as much because it requires special technology special boxes special equipment and so on and so forth now the next technology I want to talk about are called t carrier lines T carrier lines are dedicated digital lines that are leased from the telephone companies much like ISDN but they're high speed and they establish a stable connection on both sides just like ISDN now these connections are always open unlike isdns so communication can be made between the two ends whenever it's needed there's no hanging up in other words because they provide such a good dedicated link they're also expensive to use on lands although they were faster and so we saw a lot of companies used to have T1 or T3 connections and they might still do now there are different types of T connections available depending on the speed you require the first T1 is the slowest of the four types now like the other three it does create dedicated ends and it's secure and t1s are generally going to be used to connect lands together so for instance if I have my Lan on in one side of the city and you have another one we might get or lease a line from the telephone company to directly connect them if we don't want to use the internet nowadays we have the internet so a lot of organizations are going to use that and just get a very fast connection perhaps a T1 or T3 line between them and their ISP your internet service provider you might sometimes see this by the way referred to as Digital Signal one or DS1 so if you ever see DS it's the same thing as a t line now T2 as you can imagine are slightly faster than T1 lines they're not much different they're for some reason used a little less it's probably because the speed is not worth the uh upgrade uh and because the T3 is actually even faster than T1 and 2 T2 put together so if we add both of those together we'll get a T3 this is sometimes also called a DS3 and t1s and t3s are the most commonly one used T lines that you'll probably see out in the field T4 is even faster in fact it is a combination of all of the top ones meaning it's faster than all of them combined but it's also pretty expensive and for most part we're going to see if you really want to fast line a T3 and if not you'll probably see a T1 out in the field a lot of companies maybe 10 15 years ago used to connect via a T1 or a T3 sometimes you'll still see that if it's a very large company otherwise they're going to connect via perhaps a DSL or cable connection generally commercially again this was before you had cable and DSL at everyone's homes so now the technology has shifted a bit but it's important to know about this for Network plus because they're testing knowledge that you might see even Legacy information meaning old information that you might run into or encounter at an office or a building now in 1984 if you recall your history or if you were around then you might recall that 18t in the United States held a monopoly on the network carrier industry I.E phones so preceding this smaller companies were given a chance and a challenge to come up with a system that was going to rival a t that the one that they had so a company called Bell Communications which you might have heard of came up with this called the synchronous Optical Network or Sonet now sonnet is fiber optic okay so rather than being copper we're dealing with fiber optics which uses plastic or glass and delivers information and either voice data and Video in much higher speeds as a result because it's using light pulses now this achievement was so great that it sparked a new system of defining data rates meaning that the old systems uh just didn't it was so slow in comparison there was nothing that could sort of uh uh counter this and so we start seeing the OC levels like for instance one you might have seen is oc9 and that would be really really fast now don't worry about knowing the specific speeds for the network plus exam that's why I'm not covering them what you just want to make sure of is if you see OC versus like a T1 or T3 you want to know that the OC is generally going to be faster because again look at this word Optical carrier levels now in the mid um 1970s we had something called x25 which was everywhere and this was technology that was developed as a way to send data over copper wiring so not that OC stuff but more the t1s ETC and isdns but during its creation everyone in the networking Communications world had a part in creating and implementing it you might see x25 or terms and you used to talk about how they would take data and send it over these uh this technologies that it had and its format was virtually Universal however it was really limited by speeds because of the copper wiring and just because of the way that the protocol worked uh which I'll write up here and so it was replaced by something called frame relay now frame relay is a protocol that was developed basically to transfer between LAN and Wan end points in other words between My Lan and the ISP or my larger wide area network the way it functions is not important just know that it functions similarly to x25 but it's faster and it has a more modern build behind it they're also both called packet switching Technologies and we'll talk about that later but frame relay can can send smaller packets and it can send them faster we'll talk more about uh packet switching in the next module finally I want to talk about asynchronous transfer mode or ATMs if you ever see ATM on the test this is what they're referring to a wide area network uh transmission or transfer mode it was introduced in the 90s as a successor two frame relay and it was really considered a breakthrough because it was what they call an end-to-end solution that could work either desk from the desktop or remotely what this meant is that it could work on a Wan a wide area network and within the land however this sort of proves not really to be true because the technology sort of got for lack of a better word pushed out of the land market because other technologists came around that were just better it was actually pretty expensive to use but it did have some benefits one of the main ones just like with the T aligns is it could transfer data voice and video it's also a packet switching technology something we're going to talk about and it's pretty fast and one of the major things we're going to talk about with it is that it used what are called cells and the cells were 53 bytes long which is fairly large for a packet of data and I shouldn't say even pack it because what it really we're talking about is it was replaced by cells so these cells have proven to work more efficiently for transferring than packets that were used by frame relay and this is really sort of the legacy of ATM was using these cells that had a lot more information in them than the frame relay packets which were much smaller obviously the more information we could cram into a packet the faster we could send it the quicker we can get information to the other side of a network or a wide area network and if we just look at this this is just to show us that it has again voice data and video all in one cell which was sort of the amazing thing that this technology ATM did good way to remember it is to think about going to the ATM you can check your balance you can get money you can pull out of your savings you can pull out of your checking and so it sort of does a lot of things when it comes to your bank same with the ATM cell all right so those are all the WAN transmission technologies I just want to briefly go over obviously we took a very cursory overview of them and and you could probably Google and find a lot more information that's going to go over your head and you don't need to know that for Network plus but what I want you to remember again is that ISDN was used it really either came in that BPI or rather Bri or PRI modes PR was slightly faster it was either in 64 kilobits per second or 128 kilobits per second it worked over the existing pots or pstn phone system but it was still relatively slow we don't see it much anymore although it was pretty big maybe 15 years ago the T carriers the big ones you're going to see are T1 and T3 remember that T3 is faster than T1 Sonet as well was introduced excuse me it replaced the sort of tea way of looking at speeds with the OC system OC is fiber optic and if you think about the O in there being optic that's why it was faster x25 and frame relay both ways of transferring when data this was replaced mostly by ATM both of these are what we call packet switching which we will look at in the next module and the important thing with ATM again not the thing that you put your money into but rather a Wan technology it was marketed as being end to end meaning it could work from the computer to the computer although nowadays we really use it in Wan Technologies from a land to a land endpoint and the other thing it really introduced was that 53 byte long info cell which again can hold video voice and data in it [Music] thank you look at the module 9 lesson 2A least lines I'm gonna look at T1 E1 T3 E3 and sonnet synchronized Optical networking these are a syllabus talking points so kind of need to cover some of the things I think could come up it's uh Ali you've got a lot of choices when you want to connect your small office or even a larger office across to the internet or to another remote office somewhere else that you own now one of these options is a lease line which is a dedicated telecoms line now you don't install the line it'll be the roads will be dug up or wherever they put their cables will be um all laid by telecoms company and you'll release that line for a fixed fee usually monthly and you have to sign a contract this lease line is available to you all of the time 24 7. so since this dedicated line it's not shared with other users here's an illustration it's an image from Wikipedia at the bottom you've got remote users using the public uh switch telephone Network they're dialing in I suppose nowadays they'd be using broadband and um vpns they could be working from anywhere but you've got two Regional Offices on the left that need a dedicated connection of 24 7. they'll go through the telecoms network using a lease line foreign based on the technology the bandwidth of a lease line varies typically between 56k and 2 Meg to be honest there's unlikely be using 56k unless you just wanted to have um like some sort of keyless entry system perhaps for a gym where it just needs to authenticate people but even then the costs are so low now that um it's unlikely to be that slow okay some advantages we've already said it's it's your connection dedicated to you and you can choose how you allocate that bandwidth if you want to use it mainly for video conferencing or some of the some of the use disadvantage they are quite expensive and typically used to connect businesses that have a geographically distant offices so they tend to be um Somewhere Out In The Sticks and a bit more difficult to use other connections for example a broadband connection with a VPN always active and like a dial-up connection dial-ups are fairly old technology now and quite expensive okay the telecoms company will charge you monthly for use of the lease line fee varies based upon the distant speed of the connection also where you are in the world um some places the Technologies still emerging some places still established so level level of quality is assured it's not as if you can use more bandwidth at certain times of the day like frame relay and lesser others uh quite uh old technology still in quite prominent use but the technology is quite old originally used to connect your mainframes to remote sites so a few examples that they mentioned in the syllabus the T carrier and e-carrier T carrier one e carrier one and then T3 and E3 the T1 transmission system originally developed by a t 1 induced introduced back in 1961. originally uh developed to to transmit 24 phone signals at the same time over uh the copper wire he uses something called TDM time divisional multiplexing this mixes up the signal in order to use um multiple signals over the same physical link I don't think they go into any detail on TDM in the exam there so T1 will give you a bandwidth of 1.544 Meg upstream and downstream so synchronous T1 system is used in America Japan and South Korea e the e-system is generally used in Europe the bandwidth level of T1 was originally called the digital signal level 1 or DS1 I mentioned before the T1 line has 24 channels each channel is called a ds0 and you could have one two three of these channels or all of the channels depending on how much you want to pay and how much bandwidth you need each channel is capable of transmitting data at up to 64k uh lease line T1 multiple channels provide flexibility so I've said you could already choose some channels or all the channels E1 is the European version of T1 however because of the infrastructure that was in place at the time you could get up to two Meg 2.048 mag this has 32 channels in each Channel's capable of transmitting data up to 64k you can add them all up and then there's a um a signaling Channel also T3 is equivalent to bundling together 28 T1 line so much faster also referred to as DS3 since there are 24 channels the T3 is capable of carrying 672 T1 circuits so multiple companies will be using these it's not likely that B1 companies so you get up to 44.736 megabits per second with the T3 lease line if you add the whole line 30 times faster than T1 E1 is the equivalent to 16 or E3 sorry equivalent to 16 E1 lines 512 E1 channels so you get up to 34.4 mag there so T3 has more bandwidth than E3 sonnet I think is mentioned in the syllabus which is why we've got it here synchronous Optical networking this can be used as lease lines also but it uses fiber cabling instead of copper you get um higher bandwidth for that obviously because it's using fiber optic um the transmission of solid fiber networks is specified as Optical carrier or OC transmission rates oc1 is a transmission line with speeds of up to 51.84 Meg oc3 you get up to 155.52 and then OC 12 you get up to 622 megabits per second uh the oc-12 is typically used by your isps as a wide area connection you wouldn't be using it in a and small company for sure so we've looked at T1 E1 T1 T3 and E3 and also solid networking thanks for watching [Music] foreign module 9 lesson 2B wavelength division multiplexing bit of a mouthful but it's a new um objective in the network plus exam we'll look at what is a wdm that he said wmd wdm system course length division multiplexing cwdm again we love our abbreviations here a dense wavelength division multiplexing so what is it basically the idea is to get the most you can out of what you've got and this um instance what we've got is a single optical fiber and what we need to do is is get as many signals to cross this fiber at the same time as possible if you just had one signal pass in then um so the internet would grow into a whole basically it allows bi-directional Communications over a single fiber so two directions uh wdm uses a multiplexer which is um you'll often see it referred to in diagrams as mux mux and then a d multiplexer on the other side dmux d-e-m-u-x so this um if we just go back sorry it um the multiplexers that the transmitter to combine multiple obstacle signals of different wavelengths and at the other side this needs to be demultiplexed back to the original separate signals wdm systems mostly used by telecoms companies because of the capacity of the network and the again the idea is and getting more out of less so they can expand the network without having to lay more fiber optic cables which obviously take uh takes a lot of time and money wdm they're divided into two types and these are based on the wavelength patterns that are used CWD um and DWD um wavelength division multiplexing through um dwdm and cwdm these they use multiple wavelengths or lights but they differ in the spacing I'll show a diagram actually in a moment um so in the following factors a wavelength on the number of channels the ability to amplify the multiplex signals in the optical space cwdm uses a smaller number of channels you can use four or eight channels with large space in between the channels the bandwidth of each channel is 3.125 gigabits so here's an example of cwdm used to transporting data within 100 kilometers So within a metropolis area an example of cwdm is 10 base lx4 Network it can transmit data at up to 10 gigabits per second cwdm cable televisions actually use this where different wavelengths are used for the downstream and Upstream signals a dense wave then dense wave length division multiplexing dwdm uses a large number of channels it could be 40 80 or 160 but they have small spacing between the channels and here we go is an example from I'll put the link in down here you can see the difference here between the spacing and obviously the numbers um the numbers are shown in the diagrams there cwdm you can see the spacing where it's DW DM um very hard to see any spacing between the channels okay the high number of channels was the reason for the name dense wave typical dwdm system would use one of the following 40 channels at 100 gigahertz spacing 80 Channels with 50 gigahertz space in the bandwidth of a single channel is 100 Gig used for transporting data over long distances mainly used as the internet background so this cable will be laid over long stretches and um under the ocean into interconnects large strategic computer networks and core routers all right so we looked at what is wdm the system and cwdm dndm no dwdm sorry typo all right that's all for now thanks for watching [Music] welcome to module 9 lesson 2C uh multi-protocol label switching mpls so what is it a label switch path benefits tunneling [Music] it's just an overview really because they mention it once in brief in the syllabus but an mperls Network it provides one connectivity between two geographically distant offices so it's one of a number of methods for connecting across a wide area network and obviously each has its pros and cons which we'll go into mpls it's high performance it's packet switching a packet forward in it uses labels to address packets in the telecoms network now uh it's called label switching because it makes forwarding decisions of the packets based upon the values of the labels and as opposed to the usual way which is looking at the IP headers so this avoids having to look at the routing table lookups and all of the problems associated associated with uh routing table lookups cool concept is labels are assigned or pushed into Data packets this is the packets are labeled the routers in the impulse Network make forwarding decisions based upon that label you're still without having to examine the actual packet it's only the label has to be examined so say remote office say what's the same package to remote office B and the data sent by a reaches the mpls network the data will be labeled just like how we'd label um a packet if we were sending it by shipping and then the routers in the mpls network will act like a courier service the routers do not open the packet they just look at the label and decide where to send it for the next destination process continues until you reach the edge of the mpls network when the label is removed or popped before being forwarded to the remote office B here's an example of a mpls network from netcerts.net the labels in the mpls network have the information that tells the routers where to forward the packets this is a simplified diagram where the IP packet has gone across to two routers and then it's hitting the mpls network at router p e a which adds a label and then the label is finally removed at router p e Zed so there's only three routers involved in the mpls network here so as I said this is different to the traditional routing where each packet's header has to be examined each router step by step has to do complex lookups and obviously deal with all the other issues associated with routing a label switch pass the data transmission in an mpls Network occurs through a path called the label switch paths this is the sequence of labels that each and every nose along the path that establishes between the source and the destination this is all actually set up before the data is transmitted multi-protocol basically means a number of protocols can be used really the only protocol left to send over mpls is IP and ipx SPX and other such protocols or apple talk aren't used anymore at all npls is often referred to as layer 2.5 because it sits between layers 2 and layer 3 of The OSI some of the benefits not dependent on layer two technologies such as ATMs sonnet and ethernet it can be used to carry different types of traffic and ATMs on it and ethernet frames tunneling mpls can control the entire path of a packet by tunneling through the intermediate routers that span multiple segments this is a unique feature of mpls it's used in provisioning in mpls based vpns which is actually outside the syllabus all right so we've looked at mpls LSPs some of the benefits and we've mentioned tunneling we haven't gone into any detail obviously that's all for now thanks for watching [Music] welcome to module 9 lesson 2D an overview of GSM CDMA and Y Max again we're just hitting a few syllabus topics that comment here kind of mentioned in passing really but they are marked down there look at what is 2G um you may have be familiar with it if you've had a a mobile phone or I think you call them cellular phones in um America perhaps enhanced rates for GSM LTE long-term Evolution and CDMA so what is it it stands for global system for mobile Communications I used to actually be able to plug an adapter into your um a laptop and use a GSM card for accessing the internet but it was pretty slow my experience was pretty unreliable and pretty expensive so not fantastic but um if you were desperate it kind of did the job developed by European Telecom standards Institute Etsy and this is the protocols for second generation the 2G cellular networks digital used by mobiles the original standard was for 2G Wireless telephone technology and it became the global standard for mobile Communications a bit left behind now so GSM is a cellular network that uses radio signals for mobile and mobile comms the cellular network is a mobile network that is spread across the land area called cells one or more fixed transceivers or base stations were probably more familiar with they provide each cell with network coverage obviously the further away you are from these base stations the poorier signal light is until at some point you'll have no signal at all um we commonly call them mobile phones during the cellular network calls all right so what is 2G second generation as we've said they use radio signals developed as a replacement for the old cellular network they used um analog radio signals so that was a real old school and stuff they were quite easily hacked into at the time you if you had the equipment you could listen to people's um telephone conversations with a scanner the original GSM standard was actually designed for full duplex voice telephony it was just adopted for data later on originally operated at 96 bits per second which is pretty darn slow evolved over time to allow Datacom through an enhanced GSM technology called Edge or enhanced data rates for GSM evolution this was considered a pre-3g radio technology it's part of the itu's 3G definition and the idea is it delivers higher rate bits per radio channel so it's three times faster than ordinary GSM also used for internet connections a long-term Evolution LTE is today's mobile networks used something called um LTE commonly marketed as 4G you may have heard 4G LTE high-speed data rate access based on the edge and HSPA network Technologies which are Legacy download speed is 300 Meg upload is 75 so it's asynchronous CDMA is code division multiple access this uses a special spread Spectrum technology and basically the idea is multiple users can communicate independently but using the same bandwidth and they shouldn't in theory be any interference on the connection uh represents a second generation 2G Digital radio solution uses the spectrally efficient technology for mobile communication all right moving on to Y Max worldwide interrupt interoperability for microwave access now what do they've shortened that one technology is based on 802.16 standard which you can look up in your own time it delivers a wireless Broadband Services anytime and anywhere here's an image from conique.com of indirect access with the outdoor customer premise equipment connecting through a base station when you've got a poor um connectivity and but you've got the signal goes through multiple paths uh the 802.16 standard is developed for providing an online science connectivity so it'd be quite useful in um areas where there's a lot of buildings and things in the way trees and other buildings and antennas why Max is sometimes referred to as Wi-Fi on steroids similar to Wi-Fi but can provide Broadband access to a large area supports Communications over a maximum of 30 mile radius there are other available for fixed usage or mobile so why Max is the standard which we've already said download speed is up to 37 Meg and the upload speed is up to 17. mobile y next is based on the 802.16a standard from 2005. and this the got a throughput of up to 100 Meg so we've covered in brief GSM 2G enhanced data rates for GSM LTE CDMA and Y Max that's all for now thanks for listening [Music] wide area networks Wan connectivity and voice over IP in the last module we discussed the different types of Wan switching and the different transmission technologies some of which are going to reappear in this module that's because uh transmission technologies and connectivity options are going to go hand in hand so we're going to talk about some of the WAN connectivity options that we have including a least line packet switching which is different from circuit switching we've seen in the past something called cell relay which is the name implies it's related to ATM and then we're going to discuss briefly voice over IP which is something that will come up again but which is more and more become a necessary part of our networks that is making phone calls over our internet Network or our ethernet Network rather than over the plain old telephone system or public switch telephone Network and just to recall that's either called pots or pstn that was the phone network we used for lots and lots of years until we started getting more into a why internet wide world so when we talk about voice over IP I want to bring up a very important protocol called sip if you see sip on the test it is going to be directly related to voice over IP now one of the ways in which wide area networks can gain connectivity is through a leased line we've seen this in the past module at least line is sold to a company for a set amount of time thus the word least now a least line provides steady permanently set up connection such as a T1 connection or perhaps even a T3 connection or oc9 connection this connection usually allows data voice and internet connectivity to pass through it now typically these are used for establishing a Wan and connecting two different geographical locations to One Network though this connection is permanently there it can only be accessed as long as the customer is paying the lease for it this is where the disadvantage to it is this can be pretty expensive to buy a lease for because again if I have an office in let's say Manhattan and I have an office in Houston the idea is I'm leasing a direct line between the two and as you can imagine because I have my own line that's going between these it's pretty expensive the reason I lease it again is because I'm not a telecommunications company I can't just lay this cord I need them to lay it for me and then I'm going to lease it from them so the upside to this although that's the downside is that it's the most secure connection that we have now in the last module we talked about a t carrier lines and a T1 line can be leased and provides a secure connection so therefore it is a leased line and we also talked about in previous lessons switching we talked about how important switches were to the functionality of a local area network they provide a communication path between two endpoints and they manage that flow of data so that way we don't have a bunch of traffic going on in effect they basically make sure that packet going from one location gets to the other and doesn't sort of interrupt the flow of all the other packets that are going on now in Lan these two endpoints aren't very far away from each other however on a Wan or a wide area network these endpoints could be on opposite sides the globe and that's why switching is such an important topic to understand now when it comes to a win or a wide area network there are two different types of switching there's packet switching and there's circuit switching packet switching is when the data is broken up into smaller chunks or pockets and then they're assigned a source and a destination and they stop at different nodes along the way every packet has these assigned to it because they don't always stay in the same path as the other packet and I'll show you a visual to clarify this in just a second they're usually going to split up which paths they're going to take in order to avoid colliding with each other and to make it much faster this principle of packet switching is sort of similar to a torrent if you remember a torrent file if you've ever used one it contains information about data like files and folders that can be distributed now if someone torrents a file the folders and files within that torrent are downloaded to the user's computer but the torrents are peer-to-peer sharing system they Mark almost exactly like packet switching does torrents collects packets of data from wherever the data is available and then reassemble it in the whole file on your computer in other words you can be downloading information for the movie you're torrenting or of course the movie that you own that you're torrent and we wouldn't want to say to do anything illegal and what you're doing is you're actually taking that information from say 5 or 10 or 100 different systems that are out there they're all coming down into your system and then you're compiling it all together to make one movie this isn't unlike Willy Wonka where the information goes up into the Wonka vision gets split up into a whole bunch of little pieces and then gets brought back to you except all the little pieces don't have to be sent from all the same place so the benefit of this is that it can go a lot faster that's with packet switching the downside of course is that there's a good chance that the packets can be lost along the way now the second type of switching is called circuit switching this method of switching requires dedicated physical connections so whereas packet we're dealing with data in circuit we're dealing with physical connections that allow data to be transferred now it can be difficult to establish these connections but the results are a lot more reliable than with packet switching with circuit switching the connection that's made is dedicated for that purpose only in other words I create switch over which all the data is going to be sent once I'm done with that and the transfer is complete I no longer need this circuit and so it might be switched to allow another computer or system to talk to one another now there's a very small chance of the data getting lost or along the way because the circuit switching establishes a consistent data transfer however the downside is I can't take it from say 10 different sources instead I have to have one sender one receiver and in this case because I can't split it up it might take longer to find that one connection although once that connection is established it's a lot stronger so here's an example of what packet switching might look like the packets that are traveling across the network are all going on different paths right one might be going like this one might be going like this the other might be going like this etc etc they're all going to reach the destination on the right but they're going to do so in a different way if we say that this is the source and this is the destination this is going to alleviate traffic Network because as you can imagine I don't have to require everything to go across this one dedicated line instead it can use whichever line has the least traffic on it at that time and therefore everything's going to get there without with the least amount of traffic however it's also not the most secure way because obviously there are a lot more points for someone to enter in and perhaps steal information or sniff information and this packet for instance might have been gobbled up by a hacker someone who wanted to get the information or it somehow just got lost so this is where the issues with packet switching come in now in the last module we talked about many of the different transmission technologies that Wan has in one of those if you recall was ATM or asynchronous transfer mode and imagine that name asynchronous that's important because it's not at the same time it's asynchronous now ATM splits data packets into these cells and these cells again are 53 bytes in order to send them now this made data flow simple and it did not back up the system and didn't cause too much traffic so very similar to ATM is what we call cell relay so relay is a connectivity method that breaks data up into equal size cells and then sends them to the destination now unlike ATM these cells aren't necessarily 53 bytes but they're all even with each other so they're all sent across the network and they all are even meaning they each have the same amount of bytes now the data itself is transferred very similar to a method that we just talked about in packet switching the difference is that packet switching doesn't evenly break up the packs which could cause some Network traffic so cell relay is good for simultaneous transfer of data and voice meaning it allows me to do voice and data at the same time however just like with packet switching it's not very secure and some of the cells could also be easily lost along the way now as we all know voice over IP has sort of taken the World by storm international calling can be really really expensive and so voice over IP is a way to make calls through IP packets or using the internet you recall IP packets are part of the TCP Suite they involve giving every single device on a network and IP address which is just like a phone number in an old system and uh this would allow us to save money on international calls it's by far cheaper alternative to a phone service because unlike a phone service there are no monthly bills to pay and there are no long distance charges to deal with so VoIP uses the existing internet infrastructure that's already in place to make connections for calls and what it does is it basically puts the information from your voice into packets and streams those across a network now like almost everything in Computing there is a protocol that allows this to work and that is called the session initiation protocol or sip write that out now if you see sip on the test or if you see voice over IP on the test you can be guaranteed they're related the other thing you're going to see when it comes to voice over p is called qos or quality of service the reason is we want to make sure the quality is pretty good otherwise if we're getting the packet at the end you know if we're getting uh if I say a sentence and I get the end of the sentence before I get the beginning of the sentence then the quality is not really good and I can't really rely on this so getting back to sip for a second this is the protocol that's designed to set up and maintain internet multimedia sessions such as voice calls it's also responsible for communication that's used in video and audio conferencing online games voice Chats on the internet and so on so it's extremely important and without it basically VoIP wouldn't function so here's an example of what VoIP might look like as you can see there's both a phone and a computer that are connected to this network on the top end PC connects through a modem or perhaps even a network card and the telephone connects through some sort of adapter and they both connect through the internet generally there's also one box that everything sort of connects into and that sends it out into the internet out to your internet service provider and again the important thing here is that everything is being captured into IP packets so your voice is being turned into for lack of a better term data in an IP packet which can then be sent over the internet great so now we've identified some Wan connectivity options including a leased line which is a line that you lease between two places an example of that would be that T1 or that T3 line the reason it's leased is we don't actually put it in the Telecommunications Company does that for us we simply lease it for a certain amount of time it's very expensive and so a lot of companies don't use lease lines unless they require one what they use instead is a connection to the internet and then they will have uh basically virtual private networks and software and other Hardware that create a virtual leased line over a public line we also talked about packet switching which was important different from circuit switching which is sort of what switches do pocket switching would allow me to send data and if I had many different routes for that data to take it could take any one of those pack those those data packets run in sort of any different configuration I wanted it to and it would all arrive at the enemy put back together so the packets all basically get broken up sent out shuffled sent in whatever order they need in the packet each packet has the source and the destination and also it has a number basically so that way at the end it knows how to put it back together in the correct order this is somewhat similar to cell relay the difference with cell relay which is linked sormal to ATM is that all packets are the same size we also briefly which we'll talk about more discussed VoIP or voice over IP which allows us to make phone calls or voice calls over the Internet or using ethernet technology the protocol that allows us to occur is called sip or the session initiation protocol again if you see sip on the test you can guarantee that it has to do with VoIP or voice over IP now in the net next lesson we're going to talk more about remote networking obviously something more and more of us need to do with telecommuting and also something that would allow us to replace for instance a leased line with more of a temporary solution [Music] thank you welcome to module 9 lesson 4.1 practicals and services uh as usual covering the things we haven't already gone over it's a wonder wide area network still we're in brief I.E the stuff I think you need to know because there's entire books on some of these protocols PPP PPP over ethernet Dynamic multi-point VPN which has actually just been brought into the Cisco CCNA syllabus sip trunks uh Josh talked about sip trunks earlier uh briefly it he actually wrote it onto one of the slides when he talked about voice so I'll just cover an extra little bit PPP very popular over dedicated and circuit switch links for wide area connection now where the typical question you would get certainly for Cisco is if you're collecting a Cisco to a device over a wide area network to a non-cisco device what protocol would you use you'd probably use PPP because it's a vendor neutral anyone can use it whereas Cisco has a their own set of protocols that you can choose from for your server-wide area networks also works over many different link types so synchronous ISDN asynchronous DSL Etc two components inside PPP you've got your ncps which show your network control protocols these interface with the TCP or network layer talking about OSI and then you've got link control protocols this manages the data link sessions and connections that'd be a typical exam type question the other thing about PPP is it offers authentication built in which is very useful now you've got two types pap and chap uh unfortunately if we go over to password authenticate Authentication Protocol your password if you sniffed the packet been sent over the line uh the fields you would see password it doesn't encrypt the password chap actually sends a hashed value of characters whatever they may be so you don't actually see the password so this is the one you're going to want to use no one really is going to use Pap anymore unless it's um you can configure it if for any reason chap goes down you can configure it's a it's called a full back PPP fullback but really you'd probably rather just have your PPP line go down and you troubleshoot it but search up is what you will want to use because it offers the encryption there's a three-way handshake this is another typical exam question um and you can see it in the diagram here there's a challenge a response and then it's accepted or rejected if it's accepted then the line comes up and you can pass then your data if um it's rejected then obviously the PPP session uh won't come up and I spent some time debugging this when I work for Cisco Systems a continual authentication so it doesn't just do it once I'm not sure you'd have to read the RFC and see how it's been implemented but there's regular challenges take place during the session uh usually there's a a host name and password for example the host name of this router is router B and you would configure on this side here you would say the host the username that's permitted is router a and I've just used a simple password so what happens is this router's host name acts as the Authentication a hostname it calls using its um host name here and its password and in the database over here you've configured that as the parameters that's going to be permitted you can do it in a lot more complicated ways the commands on a Cisco router are PPP authentication chap uh or if you want to use um and um your clear text is pap moving on to pppoe it allows encapsulating PPP inside ethernet frames no surprise really because the clues in the name there often used with your DSL connections and it tunnels to the your internet service provider I'm just thinking of questions of the last because you're not going to have to configure this so they may ask a question what are the pppoe stage is there's a discovery which is obviously the um building up the connection between the two devices and then the actual session where the data is going to be sent across the line this is the same with most protocols as you know moving on to Dynamic multi-point vpm this allows your remote VPN connections to bypass your your headquarters VPN so in your traditional VPN service your spoke router over here say um say it's in Las Vegas this is in LA and um this is in where can we have this Atlanta a bit of a pain your branch office would have to communicate to your headquarters in order for the the tunnel to actually take place but it'll be routed from here to here and obviously if there's problems in your headquarters office for whatever reason or the line is congested your connection won't take place so the point of um Dynamic multiple in VPN is your Branch offices your spoke routers can directly make a connection and it bypasses your vpn's router you do require a hub and spoke topology which we spoke about earlier in our topology topology sessions um oh that shouldn't be in there sorry about that left that in from my last slide all right and finally I've got this slide here this image from um my netphone.com.au this explains basically how citrunks work especially an initiation protocol if you ever hear sip or a session initiative initiation protocol which Josh mentioned you immediately think voice over IP this is what enables voice over IP to work trunks enable your PBX to send and receive calls via the Internet so what it does is it takes your um the phone your typical phone connection and acts as a bridge between the internet that's the um the point of this the SIP trunk so digital equivalent of a phone line enables you to make and voice and or video calls video conferencing calls via the Internet acts as a bridge between your PBX which is your phone system that you'd have at your um corporate office there and IP telephony all right so we covered a lot of stuff but I think only what you need today and it is covered in other presentations as well uh by Josh PPP pppoe Dynamic multi-point VPN and zip Trunks and I've highlighted what I think would be the typical exam questions so that's all for now thanks for watching [Music] thank you remote access remote networking fundamentals in the last lesson we talked about wide area networks we talked about how they can be implemented what their benefits are how they transfer information some of the Technologies we use and so on and so forth now in this lesson we're going to talk more about remote networking access remote networking in wands actually really go hand in hand and if you think about it more of what we do now more than ever allows us to remote in from home to the Wan the largest land in the world being the wide area network of the internet and then access our lands at work this really allows us to not only get stuff done but is changing the landscape of how networking the internet and security have been created and how we continue to work with them so we're going to talk about this in this module and in the next couple but for this one the first thing we want to do is Define what remote networking really is then we want to identify some of the technologies that we see in place when we discuss remote networking these include VPN which we've already discussed in some raw detail or a virtual private Network radius which allows us to authenticate users once they connect and Tech acts which allows us to keep its all secure so these three are used in Enterprise settings to allow someone to remote in from home and connect to the network at work so wands are networks that are not restrained to one single physical location they're typically as we've discussed many local area networks that are joined together to create one big Wham however this isn't the only configuration they can have and remote networking is something that ties in really well with wide area Networks you see remote networking is the process of connecting to a network without being directly attached to it or physically present at the site in other words a user or group of users can remotely connect to a network without actually being where the network is established so if I were at home and wanted to connect to a network say in China I could actually connect as though I were sitting right in an office in China without actually physically being present this type of thing comes in handy quite a bit now remote networking isn't always happen between two very distant locations in fact it can be used within the same building the same room while traveling and remote networking not only works on a long distance level but on a local network as well for instance suppose that I'm an administrator in my office and I want to access the contents of a user's computer where I want to restart a server well instead of having to get up walk up to the fourth floor or down to the basement wherever the server is I could simply remote in to the server and reboot it from there so you can see that it's a huge time saving device however it also opens up a lot of possibilities for security issues and so on so here is an example of what remote network connectivity could look like the user is in China on the right and they need to connect into the network in New York here on the left so they're sitting at one physical location and they connect through a Wan which we're going to called the internet the largest Wan in the entire world and they remotely connect in some sort of way which we'll talk about usually through something called a VPN using all sorts of public networks and eventually they reach the router at their corporate office and then it's as if they are actually sitting there connected into the network they can now access resources on local clients or even on the server and all without physically being at the location in New York now there are a lot of terms we hear when we talk about remote networking and remote access most of them end up being acronyms for the sake of time and convenience but there are three that I want to specifically talk about here that we're going to talk about in more detail in the coming modules the first is VPN or virtual private network is this something we've talked before and we'll talk about late a little bit later but in essence it extends a lan or a local area network by adding the ability to have remote users connect to it the way it does this is by using what's called tunneling it basically creates a tunnel in a through the wide area network the internet that then I can connect to and through so all of my data is traveling through this tunnel between the server or the corporate office and the client computer this way I can make sure that no one outside the tunnel or anyone else on the network can get in and I can be sure that all of my data is kept secure this is why it's called a virtual private Network it's virtual it's not real it's not physical it's definitely private because the tunnel makes sure to keep everything out now the next term we want to talk about is called radius radius by the way stands for remote authentication dial in user service I'm going to write that out here remote Authentication dial in U-verse user service now if you notice there's a dial in well remote can actually be uh dialing in using a modem we don't use that much anymore but this is an older service what this does is it allows us to have centralized authorization authentication and accounting management for computers and users on a remote Network in other words it allows me to have one server that's going to be responsible and we're going to call this the radius server that's responsible for making sure once a VPN is established that the person on the other end is actually someone who should be connecting to my network remember I don't want to just let anyone connect I want to make sure the person who connects is someone who belongs to my network generally what we'll do is we'll have active directories which is what Microsoft uses to create for instance usernames and passwords and we'll link that up or sync it with the radius server sometimes this is done on a separate um a separate server sometimes it's done on the same server either way once you connect the VPN the VPN then goes to the radius server the radius server checks the active directory and now I can make sure that only users of the network are allowed onto my network finally we have something called tacax or terminal Access Controller access control system it's really long I'm not going to write it out this is actually a replacement for radius there was another replacement for radius by the way it was called diameter and if you're a math whiz you'll notice that radius is half of a diameter when we talk about circles but diameter wasn't really used much tacx on the other hand is a security protocol it allows us to validate information with the network administrator or server and the validation is tested when we try to connect just like with radius of course the benefit is tacx is newer and more secure than radius so it basically does the same thing it's just a little more powerful all right so this was short but I just wanted to give us an overview of remote networking and we're going to talk more about that in the coming modules so we talked about remote networking what it is allowing us to access a lan basically through a Wham whether that Wan is the internet or public switch telephone Network it also allows us to access the LAN from a different physical location we can also identify three remote networking Technologies the first virtual private Network creates a tunnel over the win through which we create a virtual Network that is also private we also talked about radius and tachs both of these allow for authentication so we can make sure the person who establishes the VPN is actually allowed on our Network [Music] thank you remote access remote access and implementation we've now talked about some of the basic information when it comes to remote networking and with that base knowledge it's going to come into play in this module we're going to talk more about remote access and how to implement it some of the stuff we're going to talk about is overview and some of it is still pretty basic again you're not going to take this information and just Implement a network or remote access to a network that would take a little more leg work and a little more research what this is really giving us is an overview of how it all functions and what you need to know for the exam so we're going to talk about remote access as opposed to remote networking remember remote networking is sort of the act of creating the network to allow remote access so we're going to talk about what it is what it does and the benefits for it we're then going to discuss the steps of implementing a remote access policy or remote access Technologies so remote access is a practice that's extremely useful and becoming more and more popular constantly All Around the World in every I.T situation as we've mentioned it's a way for someone to connect to a corporate land from outs from an outside location it's not always used in a corporate setting but for the most part that is its main use however for instance perhaps you wanted to remote into your home network or a home computer from the office or you wanted to remote in from outside your home these are things you could set up as well with remote access you then have the ability to connect to a physical Network without having to be anywhere near the network in fact you could be on the other side of the world and still connect as though you're sitting at a desktop PC on your land now you can imagine how this is even going to take it to another step where we could start to have computers that are on a lan or a land that we don't even control or have any physical access to at all instead all of our Computing will be done remotely this is already coming into play when we talk about cloud computing and things like Amazon's elastic cloud which allows you to set up a virtual computer on a remote system and then remote into it and through remote access and connect to it just like you would be connecting to the computers though you were sitting in front of an actual computer now this obviously speaks to not only a greatly reduct reduced amount of cost but also a lot more flexibility because now I can set up a computer anywhere in the world and for instance if I had 20 computers I could remotely access them and I would only need one monitor keyboard and mouse so you can see where this is really going to come into major play now we've already seen this before but here's another example of what remote access might look like I'm at home and I want to access the office computer so I connect through the internet to the router over at the office through something called a VPN and now it says though I'm sitting there working at the office in fact if it wasn't for the fact the boss had to see my face they would think that I was actually there so the first step in implementing on remote access is assessing it we need to before we can set anything up we need to know what exactly we are going to set up so first you need to review and determine all the connections that are going in and out of the Lan this means deciding how remote users are going to connect to the network for instance if I want someone to dial in directly they could use a modem this is going to go over the public switch telephone Network or pots the plain old telephone system alternatively let's say I have a T3 connection connecting to corporate Lan out to an ISP well then as long as people at home have internet access which today they basically would and most of them have Broadband access they'd be able to connect back through their ISP to the network second we have to understand know exactly what applications and systems they're going to need for instance I can give them access to their computer which might be one way to do it but if I have a lot of people logging in constantly remotely and I need to give them access to their computer that's going to be pretty difficult to set up and quite um uncentralized so what I might do is create one remote access server RS in which uh everyone can connect and get their profile or information this also goes with something called virtualization or cloud computing so basically they would log on to this very powerful server and they would see what looks like their computer in fact if I was basically doing this all the time I might just do this for when they sit at the office they just sit at a terminal sort of thing turn on the computer and they're connecting actually to a server that's not even located in the building finally I want to determine the number of remote users if I'm only giving this to say uh the top hun shows at the firm that's one thing that's going to be for everyone in the entire operation I'm going to need to spend a lot more time and resources devoted to setting up remote access now the next thing I have to do is think about the considerations and the things that are necessary for remote access in order to implement for instance the first step is to make sure that the remote access solution you create is flexible enough to support all those connections and the users that are that you've just established for example if one remote user is connected to a T1 Line and other ones can't get through dial up your solution is going to need to be able to accommodate both of them of course nowadays that's not such an issue because everyone has um Broadband connections but if they're not connecting in the same way or one person is going to be connect traveling around while most people are going to be coming from home well and those are all things I need to take into account next need to establish some sort of centralized access point meaning when they hit that router uh if they're coming out of the internet into the router I need something here that is going to centralize all of the stuff coming in I also don't want to just give them access to the network I might want to send them into a separate Network temporarily while I make sure that they get authenticated perhaps a virtual Lan or a Honeypot or something so it's important or demilitarized zone so it's important that I have some area where they can go and understand what the central device is going to be in some cases we could call this a VPN concentrator which is basically a device that helps set up vpns finally I need to consider security when I'm establishing this remote system as I mentioned I don't just want to give people access to the network I want to make sure the people on my network connecting wirelessly or remotely or physically connecting can all connect securely I don't want someone to tap into their connection on my end or on their end so it's really important we take security into account nowadays we have a lot of uh authentication methods that would provide you with say a key ring and on that key ring you'll have it what's called a token the token provides you with say a six digit number that randomly alternates every minute unless you have the token and that token is set up with your computer you won't be able to get access to the internet these things we've talked about in a plus but I'm just reviewing them a bit more now I also need to have some procedures and policies in place so that people understand how they're going to be able to access and what they're going to be able to do the policies ensure that the procedures are followed and the procedures ensure that the safety is used when remoting into the system so designing these policies is up to the network administrator and perhaps this Central information officer or the CIO or the Chief Information officer now it's common to have a system configuration that does not allow users to remotely access uh the system after a certain time at night I might want to do this for a number of reasons however the policies need to be whatever they are well documented and easy to understand I need to know exactly how I'm going to access stuff otherwise what's going to happen is you're going to say hey we have remote access and suddenly people are going to start calling the help desk saying it's not working properly we also want to make sure that they're accountable if they don't follow specific rules policies Etc so I need to say if someone remotes in or loses their token they could be possibly fired because that's a huge security breach just like I don't want to give my laptop or my token to someone even if it's some within the network if I've been told specifically to keep it same with passwords usernames basically the idea is the more ability I give people the flexibility I get people to connect it also makes it much more of a security hazard finally you need to make sure Human Resources is behind all of your policies they're the ones who are going to be training everyone and so if HR isn't behind you you're going to be in major issues and they're going to fight you the whole way speaking of Human Resources I bet it's pretty fair to say that not everyone is going to be qualified or knowledgeable to enough to connect to remote access so it's really important that we train the end users on what's happening on their end and how the connection works it's a good idea to have the remote users learn about what's actually happening when they connect and how to set up their ends of the connections otherwise your help desk is going to be inundated with calls and not only that but you're gonna have a lot of people upset when things aren't working properly even if it's something that they could easily fix so like the job of an admin in any other case it falls upon your shoulders to help users when there's any sort of issue this will become a lot more difficult when the admin doesn't go over to the user's desk and help them out or doesn't have the time to go over hundreds people desks you have to connect with the user in some other way though perhaps it's through a handout or through an email or perhaps you remotely access their computer or even give the computers to them set up already to to remotely connect or talk to HR about creating some sort of training program that's going to help support all of this finally once we've set all this up we need to monitor the network to make sure the remote access is working as intended the first step towards doing this is to manage all of the entry points that any of the users could use it should be kept down to one single access point and that's important because obviously it's easier to manage one access point than several father users enter the network in the same place it's going to be a lot easier to monitor them next we need to make sure that the policies and procedures are followed so when users start using wrong procedures don't follow the policies there's a really good chance something's going to go wrong and it's important to have the remote users follow a strict procedure in order to avoid any problems and to help take the load off of you and the help desk it's also very important to understand everything that's going on within the network you have to know where the connections are what they're doing what the users are up to you have to keep track of all of this stuff and there are different ways to do this different devices we can deploy and software that we'll talk about so just to recap we've defined what remote access is what it is what it does and its benefits all in all it allows us to again be geographically at a different location and connect to the lamp we also talked about lots of the steps of implementation and although this isn't very technical all this stuff comes up on the network plus exam you have to know what it is you're supposed to do so remember we talked about some policies procedures [Music] training and monitoring now in the next module we're going to talk more specifically about how we set some of this stuff up and what we're going to do to make sure it works properly [Music] welcome to module 10 lesson 2A a remote access methods so remote access is all about how you can reach various network devices when you're not at the physical location look at RDP SSH VNC telnet management through the https and file access and then outer band RDP this is uh proprietary to Microsoft so they've come up with this software you may have seen it before when you can um if you check on your Windows machine you can normally and find the uh the button to click that it will allow you to connect to a remote computer and you might use this if you work in a harp desk if you need to support a remote user you can have remote access and control via screen sharing this is actually how a lot of scammers will get people to hand over remote control they'll phone somebody who's a bit naive and say um we've found a technical floor in your computer and Handover can you hand over access so we can fix it typical exam question would be what port does it use it's TCP it has to be reliable obviously and the port is three three eight nine you need to know this kind of stuff if you need to permit this through your firewall or deny obviously now the client side can be Windows Mac or Linux there's a few different operating systems that are supported SSH this allows remote terminal access by terminal we mean a window like this where you've got command line access to a remote computer server or in this case I'm not sure what this is actually it could be a Cisco device of some sort it encrypts communication between the endpoint so most places now you can't tell Nets across the network you uh because it's all traffic is sent in clear text you have to use secure shell as part of the policy the network policy in order to use the Kershaw you have to enable it on your server router or switch it isn't usually enabled by default the client software you install on your computer the one I use mostly to get my remote secure uh shell sessions is putty it's a free download if you Google putty I think it's pretty.org you got to you get taken to BNC I used this a while ago when I was at holiday and needed to connect to my work computer this is platform independent it's a GUI based which is pretty handy if you're not too familiar with command line desktop sharing it uses remote frame buffer to a remote controller computer all right you get the TCP Port basic uh the port is um 5900 and then there's a number the number will you check the documentation but there's various numbers you will be using depending on what you're connecting to and how you want to connect now telnet is uh TCP protocol is used for remote access I did mention SSH so really tell net you'd use it at home if you've got a rack or something you want to troubleshoot you would never use this in a corporate environment now you'd if you went and did some configuration or network installation for a company and left town to open then I think you're probably um be in trouble legally because you've left a big hole in their Network for other people to connect it requires client software just uh something like putty used to have hyper terminal with a Microsoft they stopped a bundle in it with the software I think um about four or five years ago you could still enable it but you had to go into the back end and um I think you have to download some extra software but um it didn't work it doesn't work too well anyway uh uses TCP Port 23 make a note of that all traffic isn't encrypted not secure which is why we don't recommend you use it I've already mentioned this bundle blocked https management this gives you the graphical uh access method for a device when you first buy for example a Cisco router and say you don't know how to configure it you can get the router you basically plug in an ethernet cable here you connect your PC or laptop and in the documentation that will come on a CD-ROM or you get a little card it will basically say in your browser window you put HTTP possibly https and then you will put a number so say for example your home router will normally be something like this 192.168.0.1 and then that will result that will resolve it doesn't need to use DNS because it's uh the using an IP address it will resolve them to this management window and on my route up on my home router you've got a whole bunch of menus here you can configure the firewall you can reboot you can check your DNS settings you can permit or deny different devices if you want your kids to access the internet or you want to block them and you can you can configure that um firmware etc etc anyway you get you get the idea so this is your way of managing your device it's a security issue if enabled by default I'm trying to remember now I think uh Cisco devices is disabled by default but sometimes you can have different versions of iOS where all enabled and then there's something there's some change happens and the command changes or the default setting changes this is for routing commands security commands how to switch traffic packet switching and track and frame switching so um check what device you're on and if it's enabled or disabled by default generally you'll want it uh disabled otherwise you've got to configure Advanced usernames and passwords so put the IP address into the browser bar remote file access FTP is used to upload and download large files in securely so this represents a problem SFTP this is a protocol in its own right so it's not as if you've got FTP and added something to it this is its own protocol so just be careful it's encrypts a secures an eclipse traffic it uses SSH which is port 22. so um don't think that it's an FTP with some little extra bit on here security bit security issue if enabled by default this is um again I've done that again sorry I've left it from the last slide your other file transfer method is Trivial file transfer protocol which I think we've mentioned earlier if you've got a small file that you want to send over your network again please don't use this this is just what it's used for if you've got a router and you want to back up the configuration you've got a tiny little file like about a by uh eight bytes whatever or eight kilobytes probably um you'll you'll back it up here using tftp but again this file really is sensitive because it's got IP addresses passwords and heaven knows what so really using tftp it shouldn't be done anymore if you're at home you've got your little home network and you want to have a play with your software fine and if you're in a corporate environment no I I think it's a really bad idea out of band access outer band basically um it's not within your normal ethernet connection so say you've got a router you've got a fast ethernet port here and then you've got your again your PC or whatever you use to connect so this will be your in-band out of band would be something like a modem connection so you've got your router and your your you've got your telephone connection here and then a modem which is connected to your computer so out of band used for emergency access normally if you're connecting out a band something has gone wrong now it looks like this is a modem here and you can connect uh over the Internet so you could connect to the modem and then there's a a modem Port here normally on Cisco devices it's got aux written on it again check your documentation because things change over time so attach your mode and support what you would normally do is this wouldn't be connected say you're in a corporate environment so this is in your corporate Network and you've got a um you've got your remote hands so this is like your help desk team they're not they're not that technical say they're level one but you've got people who if you send them in the instructions to go to rack one and um find say Row three or whatever and ask them to plug in the cable and you'll have the cable sitting there but not plugged in you'll do the fix bring the router back up so all the other ports are working and then they will disconnect that again and you'll normally have obviously a ticketing system of some sort where you'll say plug it in and then confirm that they have unplugged it because it's a security um issue so just be careful so I've mentioned remote hands um you can use a console oh you can use a console router for multiple out of band devices so say you've got this is normally we used to do this when we were practicing for Cisco exams you out of a rack of all of these different routers say router 1 router 2 router 3 switch one switch to and you haven't got ethernet access for whatever reason so what you do is you'd have this uh a console router I can't fit it all in a console router which basically connects to the console ports of all these devices now console connections don't work over the Internet it's an out of band thing so what you would do would would tell net to this device here and then through this router here it would have the telnet the software the client software that you could configure all of these devices through a command line and um really handy way of connecting to remote racks but you could have this for your corporate Network this is an example of one this is a the the models of routers for Cisco are 25 11 and 25 21. now you can see how old this is this is your ethernet connection look at that the aui so what you do we've all we've talked about transceivers already you think but you'd have this transceiver that's got a an ethernet port in here so you could connect an Ethernet cable to another device which then lets you get in at 10 Meg um so pretty slow uh old-fashioned serial connection there I said db60 and then your console port for console connections this is your modem I've talked about your uh for your outer band access and what this is is a bunch of console connections so you can see one here they've all got numbers on and it's numbered one to eight here and then if you plugged in the second one if you needed um up to 16 devices then these numbers I won't tell you how to configure it I've got a video on YouTube if you want to look that up under my name Paul Browning and you could connect these from a load of other devices so really what you were doing is connecting to this device whatever this modeler switch is but you're doing it you're telnetting or get all rem or connected through a modem connection to this device and then from here you're choosing whatever console line is free so for example one and then you can actually configure this device so it's a slightly longer way of doing things but um that saves you having to configure tile net connections to 16 different devices so pretty handy so we covered a load of stuff RDP SSH VNC telnet https for your GUI uh access here file access and then outer band so it covered a lot of stuff so thanks for listening I'll see you on the next presentation [Music] remote access vpns and their protocols in the last two modules we discussed remote access and remote networking both are basically around the same concept remote networking meaning that I can create a network that exists in two very different geographical locations and remote access meaning that I can access a computer or a network from one geographic location to another so they're both basically the same thing but how we accomplish this in a secure fashion is what we're going to talk about in this module and that revolves around this term VPN a VPN I've talked about a bit in the future in the past rather and it stands for virtual private Network and as that term implies and like we've discussed it creates a tunnel through the net the internet the wide area network in which we can securely send uh data between two locations and why the tunnel well that's what keeps it secure and private from everyone else on the internet and this is how we've been able to allow remote networking to become so ubiquitous in our world because I no longer have to have a direct T3 or T1 line between my office and my home instead I can use the internet which is fairly ubiquitous these days and create a virtual private Network again virtual being the key word there because it's not actually a private Network it's a virtual private Network because of this sort of tunneling concept that we're going to talk about so what we're going to talk about in this module is first to Define virtual private networks a bit more and then talk about the different scene of VPN client and VPN server we've seen the terms client and server in the past so these shouldn't be too new for you then I want to talk about the VPN protocols there are two specific ones that you need to know about for the exam one is called pptp and the other is l2tp notice the T in there for tunneling so we're going to discuss both of those and how they all work all right so first virtual private networks a virtual private Network or a VPN is is nowadays an essential part of networking it's basically used anytime a network is extended Beyond a lan or local area network so it establishes a remote connection through a public network such as the internet in order to extend the Lan and I'll show you a graphic of this in just a second once the extension is made a dedicated point-to-point link point to point link which you might also have seen P2P a dedicated point-to-point link is created between two points using the same IP network meaning that even though we are on two very different IP networks I might not be on my land you might be on yours we can create a virtual point-to-point connection between the two using tunneling that makes it as though we are on the same point-to-point network the same IP network and I'll show you that in just a second now the extension of the Lan are sometimes the linking of two lands creates a new wide area network so you could say that anytime a VPN is established and a new land sort of added on a new Wan is created don't worry too much about that concept but the idea again is if I have the office slam and let's say either another office and then perhaps a remote user all connecting through VPN over the internet I now have created an effect a wide area network out of three very distinct local area networks but I haven't used any different infrastructure than something that was already there now vpns are actually a type of remote access probably the most popular one they share similarities to all the different remote access for instance you might think of dialing via modem but vpns are inexpensive way to extend your network because it uses the internet so you don't need to purchase a leased line service now remote users just Connect using the VPN to their remote office through the internet and so that's really the key here is it uses the internet as its platform so this is what access through a VPN might look like the remote users connect let's say from home through the internet and then there is a authentication server that verifies that this user is allowed on the network once you pass through that it puts you into a switch which then makes it as though both of these computers are on this LAN so in effect I've created a new Wan without having to lay down any extra line because I'm again using the internet now say that this was an office building it could have an office building here perhaps another one and these can be any place in the world and because I'm using tunneling through the virtual private Network I create an effect a tunnel which allows all of these to each create a point-to-point connection between themselves and this authentication server that then basically puts them onto this Lan so any one of these offices is now part of the land and in effect then making a brand new Wan or wide area network now there are a lot of things we need in order to set up a VPN connection and some of them are more important than others but I'm just going to key in on the the main things we need first we need a VPN client now the client is the remote access user without this user there's no point in setting up a VPN so why bother if no one needs to connect they are one of the most important clients or the ways that we components rather and what's interesting about a VPN client is it can either be software or Hardware if it's software then it's built into the operating system generally or into the networking package of the operating system if it's Hardware it's generally either built into the router or it's a separate device which is generally called VPN concentrator now the benefit is if I have for instance two offices we'll call them office one and office two and they are located in different parts of the world but they both connect to the internet then I don't want each so let's say each of these offices has we'll put four users for now but let's say these four really represent 4 000 users I don't want each one of these people to have to set up on their computers a piece of software that's going to allow them to connect through this tunnel so instead what I've done is I do something on the network side of the office for instance in the router or with a device that automatically creates this tunnel between the two offices and then these members don't have to do anything now if I am a lone user at home then I'm probably it's going to be easier for me instead of buying a device that's going to allow a network to always set up to just plug in through my computer and put it into the software whenever I need and if I go into Windows 7 real quickly go over here into our Network and Sharing and say we were going to set up a new network you can see right here it says set up a VPN connection and if we go and do this you can actually connect to a workplace now connecting to a workplace what they really mean is setting up a VPN connection so I'm going to click next now you can see I can either dial directly which is something that we might have done years ago or one the one we're going to use more likely now is the through the internet connection again creating that VPN we could call this whatever now one thing we would need here is the server address we'll talk about that but why in just a second but we are the client and we need to connect to a server so this is where for instance that server address is going to go now you know this IP address wouldn't work because this is a private IP address but we're just using this for the time being right here you can use sharing Etc but for right now let's just go ahead and click next let's say our username so let's say user and then we have a password I'm just going to do password we can have it remember the password or not you might have a domain if you're connecting to a Windows computer and then you click connect the next thing I need obviously is something for the VPN client to connect to and this is the VPN server the VPN server not only allows the connection to take place but is also going to authenticate the client and allow them to connect now this might be done through again some sort of device like this VPN concentrator I've mentioned or through a separate server that has software hooked up on it either way I need some sort of device that allows outside clients to connect in to the network basically to give them permission act as sort of a a controller or or a Gates person uh there are different ways of setting this up and you remember I mentioned something called an Ras remote access server and the specific one we mentioned previously was a radius server which was a remote access dial-in uh server and although this was for dial up it still does the same thing which is it allows someone to remotely access the local network so we have some sort of Ras and again an Ras stands for let me just write that out remote access server now the access method is also pretty important without a connection there's no way for a user to get onto the network so most of the time this connection comes from the internet but it's not uncommon for a VPN implementation to actually come through a private intranet as well so we have the internet which is the public version but there's also something called the intranet if you recall the internet is like a private internet and sometimes we might actually have a private leased line or we have several different sub networks within a larger Network and so it's important to know where your people are connecting from most the time you're not going to see the intranet it's all going to be through the internet and sometimes you'll also have people dialing up so it's all important to know even though internet is the most popular sometimes we're going to be doing it internally through an intranet and finally there are two protocols that we need to know about and the generally are set up on the server side and the client needs to be configured to set up through the first is PP TP which we're going to talk about in a minute and this stands for point two point tunneling protocol the other is l2tp which stands for Layer Two tunneling protocol and if you remember talking about the OS and I and the tcpip models that's what that layer 2 refers to so let's talk a little bit more about these protocols the VPN Protocols are really important to the security and efficiency of VPN so the protocols manage establish and secure the data that's going on through that VPN connection so pptp and l2tp are the two most common protocols that are out there they function pretty differently but their jobs are fairly similar they enable encryption which means the data isn't sent in its sort of plain text format it's sent in a way that if you were just to see it it would look like it's all gobbley and so what happens it's set on one end in a code and then received and decode on the other end and it also provides authentication so only those who are allowed on the network actually get on the authentication it also establishes the identities of the people in the network so we can audit them it's a way for the clients and the servers to be on the same page about who is on the network and like I mentioned encryption is really for the data protection so because we're going through the internet which is public this is really at risk for attackers and so the encryption protects that data that's traveling through the network and prevents these issues from happening generally speaking we're going to prefer l2tp over pptp just because it's a more advanced protocol and uses a different form of encryption I think in fact Windows 7 and Vista only allows lttdp now it doesn't even allow pptp as we just saw when we looked into windows all right so just to recap what we just talked about first we mentioned virtual private networks which you'll never see referred to as virtual private networks you'll see them referred to as vpns and those basically create a tunnel through generally the internet sometimes the Intranet to connect lands together and in effect then creating one large Wan now this can be done between office and office or say a home user in an office and either way you have a VPN client which would be the one connecting to the server and remember we have either software or Hardware we looked at the software that was built into windows we also have Hardware the generally the thing that you'll see with there is something called a VPN concentrator it could also be for instance built into your Soho router or be built into a Cisco router of some sort as well we also discussed the two VPN protocols remember these were the point-to-point tunneling protocol and the layer 2 tunneling protocol notice that these both you know are VPN protocols because of this T the tunneling protocol generally speaking we're going to see l2tp used more than pptp and what these really are responsible for is defining how encryption takes place and authentication which is something that works in conjunction with the VPN server to accomplish [Music] welcome to module 10 lesson 4 gra SSL VPN and VPN concentrators we look at them secure sockets for VPN also what is SSL VPN concentrators ipsec this is just an overview as usual there's a whole entire um exams for security stuff like this in more detail like the CompTIA Security Plus which we host on howturnetwork.com and the CCNA security also GRE stands for generic routing encapsulation and it was actually developed by Cisco Systems as a tunneling protocol and I totally in protocol tunnels something else another Prodigy call within a protocol so it allows Network users to access the network service it's not supported by the underlying Network so you can actually tunnel um lots of different things you can sort of IP version 4 inside IPv6 if the um hop by hot pair devices don't support it here is an image of a GRE tunnel going across an internet Source interface or IP address destination IP address of the tunnel an IP address of the tunnel that's part of the configuration you don't really need to worry about that but the traffic will pass through the GRE to Norm and the device is actually sending the traffic will only examine the header of the GRE packet which is um wrapping the uh the traditional IP traffic so we already know we can run a protocol every Network you can actually run non-routable addresses as well so inside that tunnel you could have a 192 address and as long as the tunnel is going via routable IP addresses you'll be fine a gra creates a virtual point-to-point link and encapsulates a variety of network protocols uh yeah I've already mentioned the private IP addresses it's used in conjunction often with pptp point-to-point tunneling protocol and ipsec if you want to create a VPN and there's an image there for with the GRE tunnel also working with an IP sector null from networkstraining.com uh VPN a virtual Network a virtual private network is a full term it's built on top of an existing public network obviously very handy if we need to securely connect over the internet from um two different network locations often used by companies because they don't want to buy a dedicated lease line so they'll just use existing security technology you have a secure Communications between two private Networks SSL VPN this is a secure sockets layer virtual private Network it provides encrypted communication between a clients and server one example is SSL equips communication between a web browser and a web server and your browser will be a Google Chrome or whatever you're running on your laptop or PC the user connects to VPN devices using their web browsers traffic between the web browser and the VPN is encrypted with the SSL protocol so as a result you've got a secure access to web applications and client server applications you'll see this working with the um green padlock when you're browsing different websites built into all standard web browsers you'd have to add anything extra on you don't have to configure or install any client software anymore you used to have to that was a few years ago now and it's all built into the web browsers uh the SSL VPN can be accessed from anywhere including airport hotel rooms coffee shops as long as you've got web connectivity and the user has a standard SSL client that's used with that particular SSL VPN uh SSL VPN products usually Standalone Hardware Appliances and other software Solutions available speak to uh whatever the whoever the sales representative is for Cisco or whoever you're using for the technology you also get common security services such as authentication encryption Integrity protection Access Control who can access even how long they can access for security and endpoint security controls in choosing prevention IPS authentication as we know I'm sure is just authenticating that particular person to verify they are who they say they are encryption encryption protects the con confidentiality of the data as it passes through through the internet Integrity ensures that the data is not altered so um there's a whole bunch of ways to um showing and offer Integrity of the data as it's sent from the source and received at the destination Access Control gives restricted access and that can be based upon a number of things and the access control is then associated with whatever privilege is you wanted to give that particular user the endpoint security controls checks the user system for compliance whenever the user attempts to use the SSL VPN intrusion prevention checks the data for any Potential Threat after it's been decrypted VPN concentrators these were supported originally when I worked at Cisco by the security team they provide a remote user with secure access to the organization's resources and the concentrator is basically an endpoint for multiple VPN connections so there's maybe lots of Home users or people dialing in and Mobile sales people that need to connect from certain places and the VPN concentrator will be the point where their connection is terminated all right uh the concentrate is a device it can handle multiple tunnels coming in a VPN they provide VPN encryption either by using ipsec or SSL again check with your vendor for documentation ipsec is IP security provides a high level of security and encryption and because client software to establish the VPN tunnel ipsec is better for fixed locations SSR when the remote users need to connect from various locations for example they're a traveling salesperson and nowadays VPN concentrators are not manufactured as separate devices they normally combined with devices that also provide firewall protection if you go to cisco.com and then click on I think it's sales or products you'll see the type of devices that are available and what they do all right so we've covered a fair bit GRE tunneling VPN SSL Security Services of SSL VPN and a VPN concentrator on ipsec that's all for now thanks for watching [Music] Network management Network Administration in the previous lessons we've talked about a lot of the technical aspects of networking including remote networking remote access virtual private networks local area networks wide area networks and so on there's someone who's required to sort of put all of this into place and that's where an administrator comes in so in this lesson and in the following modules I want to talk about what an administrator is and some of the tasks they have to do in this module in specific we're going to start by defining an administrator or network administrator now there can be several administrators at any one's site but we're going to give an overview of what an administrator no matter what their specific role is going to do then we're going to identify some of the key admin duties and these might be documentation and monitoring we'll talk more about these in further modules and we've probably already mentioned already mentioned these to some degree so some of this might be recap in some cases it might be overview but a lot of what's on the network plus exam is is sort of applying not just having knowledge but applying the knowledge in certain administrator roles since that's what they assume you're going to do with your certification so there's no doubt that we have used administrator or admin for short in uh hundreds of times by now so it might be useful to stop for a minute and actually take time to talk about what this term means so the administrator of a network is the most important person involved in network it they are in charge of everything that happens on the network and know what all of the users are doing in charge of security and they can be held responsible for everything that happens on their Network so not only are they responsible for sort of creating the network but if someone misuses the network the really acts is going to fall on them more than that they're in control of all the accounts the resources the data that users have access to the administrator is the only person that has access to everything in the network and can control what others can access even if they give access to say an assistant administrator in the end if that assistant administrator screws something up it was the administrator who gave them access in the first place so clearly this is a really important person and are essential to managing and monitoring the network without them there really wouldn't be anyone with enough knowledge or ability to manage how these networks and you can see how large they get sometimes so here is essentially what an administrator's view might be like they have a view of everything that happens going in right they know all of the nodes all of the servers and this is very simplified all of the routers and switches this is what we might call a network diagram we might also have printers and if this is a cloud environment as it seems to be then they're going to be aware of all the virtual sort of stuff that is set up they're going to beware of all of the user accounts the network security they're also going to be dealing with all the remote access if there is this going out to the internet are there firewalls are there intrusion systems etc etc so they really have an overview of everything they have to maintain everything as well you can see how complicated this can get which is the reason why one network administrator might have several under administrators to help them they not only log when someone comes in or out they can see when someone visits a specific website when they're sending or where they're sending data what the type of data is we might also have for instance an exchange server which would be for email in which case we need someone to manage that as well for instance what if someone sends a 50 megabyte or 50 gigabyte file by email or they try to that's going to log up the entire network so one of the first duties of an administrator is documentation there's a couple reasons why this is so important when it comes to managing and running a network it's going to be the focus of its own module but it's good to get a basic understanding right now because the process of documenting everything can be really time consuming but it's also really worth it can save you a lot of time trouble and money when things are well documented and no one has to go searching for them especially if the administrator is out of town or if we switch administrators we want to make sure that the network can still live on its own now there are no shortage of things to handle for the administrator and documentation is OB usually the thing that's going to get pushed aside and forgotten about but there are some really key items that we can look over that are helpful to be dealt with first of all properly documenting information is useful when training new admins it's not uncommon for the old administrator to leave and then have to train a new one is their replacement however the new admin doesn't have time to learn the topography the cable connections everything about the network from scratch so this is where proper documentation is really helpful it can save the new administrator a lot of time and effort especially if even if you're not leaving if you bring on someone to assist you allowing them to look at documentation is going to save the super administrator time from having to teach the new administrator it's also going to help us when we troubleshoot problems on the network it can save time and money because we can eliminate the time it takes to test every possible problem because we can now isolate where the potential problems are for instance if I have an overview of where things are set on the network and I know one side of the Network's not working then I can automatically sort of go to that side of the network and not have to worry about the other side finally it's also really important when I'm bringing in outside workers to make changes to the network they need accurate and up-to-date information about the network its layout and if they don't have an idea of how my network looks and I just start to tell them to fix things they're going to have major issues and one of the things that's really big these days is having a contractor come in because we're sort of going to Outsource a lot of our network administrator duties or sometimes the administrator is not a specialist in something Sprints in security and so they need to bring in contractors to implement a better security plan now monitoring is also an extremely important job for the administrator it's necessary to monitor a network for a lot of reasons and again we're going to talk talk about this in its own module but it's good to understand it a little bit right now so when you monitor a network the administrator can almost always find faults in the system and find out where they are there are tools that help the administrator check all the devices to find out where the faults are and how they can be fixed and I think we've looked at some of those and we might look at it a couple more but some of the tools the Ping trace route Etc looking at routing tables looking at broadcast all this stuff and also performance detection is very important when we're involved with network monitoring when an administrator monitors performance they're able to find some very useful data they can discover Network usage data how each user has been using the network and make sure that the bandwidth is load balanced properly a term that we have seen a bit and we're probably going to see a little more and also we can make sure that nothing if there's not too much traffic on the system obviously too much traffic slows things down and makes everyone miserable finally security monitoring is really essential because uh one thing we don't want is someone outside of our Network getting access to all the stuff we set up it's really going to make your bosses upset too and we're not just talking about hackers we're talking about viruses attackers any of this stuff so when we're monitoring security an administrator can find holes in the system and then take preventative actions in order to stop the attacks before they happen one thing that's going to help with this are two devices called an IPS or an IDs an intrusion detection system and then an intrusion prevention system these are actually two different things as you can see from the name intrusion detection just detects when something happens intrusion prevention is actually going to stop it in its tracks so that was just a broad overview of defining what an administrator does the person who overview who has a complete overview of the network and then we looked at a couple of the reasons why their admin duties of the documentation monitoring are so important documentation for training new people tech support uh bringing in outside resources and also monitoring not just for uh security reasons but also for performance because obviously if we have a slow Network it's going to result in everyone being unhappy and your boss is not being able to be able to accomplish the work they need not to mention if we talk about one extra minute in work time that can actually cost us quite a bit of money in the real world so having giving us a broad overview of this we're going to talk more about uh optimizing a network Performance Based on the monitoring that we do [Music] thank you Network management optimizing Network performance we're going to be covering a lot in this module it's all about the optimization of a network and its performance and there's a lot that we have to do as administrators when it comes to that we're going to specifically focus on strategies to optimize network speed and efficiency so first we're going to give an overview of what network optimization is and then we're going to define something called quality of service qos which I want to point out right now you're going to see anytime we talk about voice over IP this is the name implies what we're doing is trying to make sure the service provided on our network has a high degree of quality and when it comes to voice over IP we need to make sure the quality is pretty high there are two ways to do this one is called latency sensitive and the other is latency insensitive and we'll Define that a bit more we're also going to talk about something called traffic shaping and methods in which we do this and finally caching engines which help speed up Network performance as well so bandwidth is essentially the amount of data that can be transferred and utilized at any given time this amount is usually expressed in bits per second so if you remember we see for instance mega bits per second with the small B and I want to point out again that this is not megabytes per second as you recall there are eight bits in every bite so we would really need eight mega bits per second to equal one megabyte per second just something to keep in mind as you purchase uh perhaps a broadband connection now how the bandwidth flows is dependent on how many people are using it at once and for what purpose so everything in today's world is expected to be fast and we can settle for no less than the fastest it will become really impatient with network speeds very easily and unfortunately they fluctuate fairly easily too especially in a corporate environment where there are a lot of people using and taking up the same bandwidth just imagine how frustrated workers are going to become with uh when they can access something really fast one second and very slow the next you can imagine this at home as well so the purpose of network optimization is really to help control the traffic on a network the large group of people are trying to enter a building through one door the flow is going to be a lot slower than if there are multiple doors and the same principle applies to networks if the network is laid out and run in an optimal way there is less chance of blockage so in addition to network traffic optimization Works to utilize bandwidth in the best possible way so that everyone can use it at the same time this would be also called throughput so whereas bandwidth is our ideal or possible throughput is the actual in other words what actually makes it through the bandwidth so here's a representation of what bandwidth might look like imagine the bandwidth capabilities are like tubes and the bigger the tube the more that is free to throw flow through it so here you can see there's much more ability to flow through the tube on the right because it's a lot bigger than the tube on the left that being said only because our bandwidth is for instance 90 megabits per second or one gigabit per second doesn't mean that the throughput is actually going to be that I'm sure that you have at home uh bandwidth or broadband internet and it probably says it has up to perhaps maybe 15 megabits per second if you're on cable but sometimes you're not always getting 15 megabits per second you might be getting five or eight megabits per second and you can test this using different sort of online speed test uh utilities but only because we have a certain amount of bandwidth doesn't mean our throughput is going to equal that which is an important distinction to make what we want to do is get the bandwidth and throughput to equal as close as possible to one another so there are strategies used to increase the use and optimization of bandwidth on a network these strategies are called quality of service or short-term qos now they have a lot to do with information and helping it optimize the network so qos allows administrators to predict the bandwidth use on their Network monitor the use of it and then control it this is done to make sure that there is available bandwidth for any one application that requires it the applications that need this bandwidth are generally split into two different categories latency sensitive and latency insensitive latency sensitive applications are appropriately named these are applications that are affected by latency or a delay caused by a device so latency is sort of the slowness with which bandwidth occurs or not living up to its full potential so an application that needs bandwidth because of its Effectiveness is impacted by lag time for example applications that use VoIP fall into this category or voice over IP they're latency sensitive because lag time could disrupt a video or a phone call latency insensitive applications still require bandwidth but for a very different reason these don't have video or voice transfer so the bandwidth is just as important to them but the latency doesn't really matter these applications are those that are used to transfer large amount of data like during backup or FTP just to cover this one more time and perhaps say it in a different way latency sensitive would be meaning that if something for some reason I have a huge uh amount of traffic then I'm going to start seeing a degradation in service when it comes to my latency sensitive applications such as VoIP for instance I need to make sure that no matter when I'm talking over my VoIP phone it's still reaching the end person in the same degree of quality it can't be dropping a lot of packets because if it is then they're not going to be able to hear my voice very clearly with latency insensitive the traffic can modulate quite a degree because as long as the files get from one end to the other if at one point it's transferring at 90 megabits per second and the next the transmit one gigabit per second it's still going to get over to the other place but it doesn't really matter if I don't receive the packets in a sort of steady stream so in this case the latency doesn't really matter as much as the fact that it simply gets from one place to the other it within a certain degree of time so a very important qos strategy to help exist to help control the flow of data through a network is called traffic shaping its main purpose is to reduce latency which it does by controlling the amount of data passing through a network data traffic is sort of split into different categories and put put in something called a queue a queue by the way would be something like a line basically I'm going to put certain types of information into one queue and certain it to another and those cues are going to be given priority so my voice application is going to have the highest priority whereas maybe my FTP will have a bit of a lower priority now there are quite a few different ways to use traffic shaping and each method has its own benefit and needs to be chosen based on the circumstances of the situation now here are a couple of the common methods actually three first is shaping by application this is a strategy that involves the administrator allowing only a certain amount of bandwidth to be used by a certain application for instance an admin only allows a VoIP application to use for instance six megabits per second and it can't use any more than that so in some ways we set a limit to the bandwidth that's going to be used by a certain protocol or a certain application the next which is called shaping Network traffic per user allows the administrator to limit the bandwidth that any individual user can use now shaving by application is something that we're going to be seeing a lot now on airplanes and trains we don't want to let for instance people use Netflix and YouTube on the plane because there are other people who need to be using email and so we're just going to say if you want to do bandwidth for video we're not going to allow that as much as bandwidth for say email or for text messaging for instance but when I'm talking about Network traffic per user I'm allowing specific users to have a certain amount of bandwidth so some users might use more bandwidth than others and sometimes it isn't all for work reasons for instance let's say that Anthony from sales is constantly streaming video or audio to his computer this is using a lot of bandwidth so now the discipline part of this may not be up to the administrator but he or she can certainly limit the amount of bandwidth Anthony is allowed to use so if each and visual for instance Anthony is limited to 256 kilobits per second it's not going to access what he can access just how fast he's able to access it so whereas this is really doing it shipping by application based on the type of information shaping the network traffic per user is on an individual basis and this way I can give each user let's say Anthony Maria Amy each a certain degree of bandwidth so that no person can use one more than the other of course a downside with this is if Amy's only using let's say 10 kilobits per second to send emails and Maria is on the video team and is trying to use all of her 256 she might be able to use some of Amy's but because of the way we've shaped this per user Marie doesn't get any more and sometimes what we'll do is give people in certain roles the company a little more traffic or bandwidth allowability than some of the others for instance accounting probably doesn't need as much as our Graphics team finally we have something called priority shaping which is the way to allow more bandwidth to to those who require it most sort of what I'm referring to here for example in a school system the teachers need more bandwidth in the students so the network admin shapes the traffic again we have that great term priority shaping so that it's dedicated more to the teachers but the students can still use it at a slower speed so when the teachers don't need the bandwidth the students are able to access it at faster speeds so we're really taking this sort of concept and allowing it to be a little more flexible now another technique used is something called a caching engine caching is essentially temporary storage although the storing of what is changing every single time in the case of caching engines the temporarily storage of data is actually web data that can be used in the future so this is happening through something called a proxy server basically what's happening is without going too far in depth into it is that a proxy server caches web data for future uses by others so if I have let's say three users and the first user and I have a proxy server in between them before it goes out to the internet and the first user requests CNN the proxy server which holds a cache or sort of copies of everything we'll first say hey I have the latest CNN or I don't have the latest CNN it'll then go out to the internet get the latest CNN and hold that in its proxy now when the second user five seconds later says Hey I want the latest CNN the proxy server does not have to go out to the internet we can basically cut out this entire process and instead it just Returns what it is already cached it can do this with as many uses as possible and what we'll generally say is that every minute or every few seconds it's going to update the proxy server is going to update its information that way we can make sure that it's still the most up-to-date information which is one of the downsides of using proxy servers and caching is that sometimes um it's not going to have the most up-to-date information but it certainly speeds things up by cutting out this whole process of having to go out to the Internet by keeping it locally now this all saves bandwidth because obviously I'm not having to go out to the internet and therefore I can reserve that bandwidth speed that would have been used for video or something else that's new uh instead of having to use it for information that I'm gathering over and over and over again you can imagine in a corporation of thousands or hundreds of thousands of people this is really going to save us a lot of time all right so just to recap we talked about Network optimization there were a couple terms we mentioned first was bandwidth bandwidth is the highest possible speed that we have on our data connection we also talked about something called throughput whereas bandwidth is the ideal or potential speed throughput is the actual speed how much is actually traveling and what we want to do is get these two to equal one another as much as possible however we also want to make sure to make good use of our bandwidth so that everyone can get information they need when they need it so then we talked about something called quality of service quality of service make sure that we're using our bandwidth in a way that's going to promote good quality we talked about two different types of applications in ways that we use quality of service first we look at latency sensitive applications these are the applications that where there is latency or another word for this might be traffic it's going to reduce the speed on the network the quality of the service is going to start degrading so voice over IP is a great example of this if there's a lot of things going on in the network then our voice over IP isn't going to work as effectively and then I can't count on voice over IP as a good technology so it's important that I make sure Voiceover IP always has a certain degree of say bandwidth with latency insensitive applications we're looking at stuff where the speed although it still needs to be fast doesn't matter if there's latency one second and no latency the next when we're transferring high high or large files such as through FTP then we don't need to make sure that we're not modulating between 90 kilobits per second and 90 megabits per second or one gigabit per second as long as the data gets to where it needs to go I don't need to make sure that it's getting there at the exact time because for instance with voice over IP if I'm talking it needs to be able to reach the person sort of the degree that I'm talking but with FTP it doesn't really matter if it's getting there in the same instant we also talked about traffic shaping which is one of the ways that we use quality of service and we shape the bandwidth so that it is used in an appropriate way we talked about three different ways of doing this the first we talked about was based on application so for instance I'm going to give a certain degree of bandwidth to one application and a certain to another once all the voice over IP bandwidth is used that's it once all the FTP bandwidth is used I don't have any more and so I'm only giving if I have a large bandwidth let's say this box represents bandwidth then I'm going to sort of divide this into layers so FTP gets some HTTP gets some voice over IP gets some Etc we also talked about user specific which means that instead of dividing things up based on the application I'm going to divide it up based on the individual so Maria gets a certain amount Anthony gets a certain amount and Amy gets a certain amount finally we looked at priority shaping which is a really cool term and what this means is I can give certain priority to certain individuals or groups so for instance we use the teachers versus students comparison teachers we want to have a lot more than the students so students get a very small amount whereas teachers get a very large amount same with on a corporate Network perhaps I want a management or my Graphics team to have a lot more than say my accounting team or lower management or the secretaries finally we talked about caching engines and we use the word proxy server this is going to save us time because whenever I go out to get information from a website I don't have to go get the information fresh every time instead I'm going to use the proxy server to hold a copy or a cached version of my website and that way I don't have to go out to the internet every time and I can reserve that bandwidth for other things I might need to use [Music] thank you okay welcome to module 11 lesson 3 Network documentation a little bit um of a harder on this it's just a bit easier Terry can wishy-washy um although it's obviously important but just to discuss and what is it I'm sure you could actually work out well one network documentation is why do we why do we have it importance of it parts of it and many General assets and our Network diagrams RFID which we go into tracking our IP address utilization which is quite a handy thing to have actually information about vendors and contractors and all of our policies and procedures so the whole principle behind Network documentation is professionalism really and business continuity and it's um an emerging field and in the world of I.T non-technical but looking at audit trails and um yeah in the context of documentation really and all of our procedures so critical role and especially when there's a problem because people start scrambling looking for what to do in terms of procedures and policies who does what um where to find them how to contact them and um where the technology is and how to fix here there's a whole bunch of procedures and documents that have to all be easily accessible and come together and bear in mind that um the network could be down there could be an outage so if it's contained on a service somewhere then that might not be um ideal if it's only kept on the server anyway so um you can't remember everything especially if it's a large Network or even worse if it's a small company and somebody leaves the business and you take over from them if there's no documentation then it causes a lot of Heartache um and yeah if you're the one to have joined it's um it's pretty difficult because you've got to learn the network from scratch and it's not possible to go and search a network organization administrators who've quit don't believe they have their phones taken off them or they're just going a long vacation so you don't got to find them so it gives Network administrators information about the network appearance logical versus physical baselines how it's performing I should perform to see if there's anything um out of the ordinary um where to begin troubleshooting so the main purpose is to keep the network running smoothly so we've got that five nines 99.99 uptime ideally it's important to maintain the documentation and keep it while maintaining means keep it up to date because out of date documentation actually causes more problems than it fixes because all of a sudden you're looking at the wrong devices or the wrong ports or the wrong IP addresses and I've been there um so yeah that's what I've said essential Parts include Network diagrams Asset Management IP address utilization you could have more or less depending on your organization and the size of it you did information about the vendors and contractors procedures and policies who should be doing what and when and also logical and um physical this is a a topology diagram of all the hardware and the connections we haven't named the ports on this particular diagram it's copyright as Scott McDonald uh just to give you an idea this looks like it was done in Vizio which is a Cisco Network creation um diagramming tool there's others out there it's a free to troll or some are free to use and it shows you all your different devices The Logical provides the logical view of how the network sees itself not how we will physically see the network in the server room uh indicates how the traffic flows between devices in the network so you'll see all of your vlans routing redistribution all these kind of things bgp if you have it a logical net Network diagrams include domain names IP addresses and the tasks performed by each different device logically includes how devices communicate with each other which direction the traffic flows and how all these devices work together the physical network shows the actual physical connection so you can look at the diagram of a certain router and you can see which ports are on the router how many and what it's actually physically connected to and a lot of companies use the concept of remote hands so you can use these diagrams to tell the remote hands where to find the device and which cable to plug unplug Etc physical network is the physical layout that I've mentioned so here's a typical diagram above is the physical topology and below is logical topology so you might not necessarily see all of the hardware devices you're going to see things like vlans connections going out to isps and hot standby routing protocol all this kind of thing uh you won't generally see end devices on the topology diagram so this is a very small Network or unless one of the end devices happens to be your network management server or something like that so your documentation should include notes about Asset Management a whole bunch of things name model number manufacturer data purchase a version of software running does it need updating is there problems of that particular release of software updates location warranty and who has it who's responsible for it if you're sitting under some under somebody's desk and nobody knows and it doesn't serve any purpose so you should keep track of all your assets and eventually there's normally a disposal a procedure as well where the devices are wiped and fragmented defragmented whatever and whatever type of um scrubbing is done on their drives if necessary so there's no data that's important devices are tagged with the barcodes or RFID is an example of one here these are normally read by little um reader gun like you find in supermarkets if it's been tagged with a barcode a barcode scanner will help retrieve information and the RFID stands for radio frequency ID tags that normally have electrically stored information and the readers are used to track devices this would obviously be on a pretty big Network um yeah Network documentation should include your IP address utilization there's normally one or two people in charge of allocating addresses or blocks of addresses because they're aware of which addresses should be where which subnets and which addresses are summarized and this helps with all of our routing updates I have seen problems in the in the past and people should know better in fact have manually allocated IP addresses to their devices for whatever reason and it's caused Network instability so Network administrators should keep track of the number of IP addresses that have been allocated to the network how many have been in user it'll normally Flagger pay alert if you're running short if a subnet grows the number of IP addresses assigned to it you're likely to have a problem okay all important to keep uh you know the utilization as I've said in case we need to run out or buy some more order them in advance you should also have information about vendors and contractors that should include vendor names their services the cost contact information we normally get our point of contact and the support hours or should have um documentation about all of our policies and standards well worth looking into a project management and also ITIL exams so change management and managing all your processes and procedures and problems and on the network uh provides for example the list of people who should be contacted certainly when I worked on a pretty large Network there was a number of key people so you have thousands in the organization that you would contact four or five or six key people and they would each have a role of who's going to communicate to who who's going to tell the boss and do the does the press or other customers need to be informed of what's going on this is to stop uh confusion and also track back as to who should have been doing what policies require compliance and in their enforce discipline or disciplinary actions or obviously training if a person hasn't been given sufficient training and normally an acceptable use policy which new people will sign and everyone has to sign if there's any changes you standards of acceptable behavior on the network for example creating strong passwords is a very good one and obviously not putting it on a Post-It note and sticking it on your monitor so we've covered Network documentation why the importance parts of it diagrams Asset Management the RFID and monitoring your IP addresses vendors and contractors all your internal policies and procedures all right so that's all for now thanks for listening [Music] welcome to module 11 lesson 4 Network troubleshooting model he'll actually develop your own model as you get some experience and obviously depends on your Network whatever your network or if you're managing just a small part of the network and if you're managing a certain OSI layout for example firewalls or you're a hardware engineer something like that so it could vary this is the generic kind of stuff that CompTIA want you to know and understand and follow so we'll identify the problem establish a theory of probable cause normally Whoever has just made a change or plugged or unplugged something has broken it in my experience test the theory to determine the cause establish a plan of action and then implement the solution sort of Common Sense stuff really uh verification documentation all right so we'll normally gather information duplicate the problem if possible you'll normally duplicate it if it's some sort of bug and you want to recreate it so you can send the information to the vendor to release some sort of update uh question users users you've got to be very careful obviously because they can give you the wrong information or a lot of users think they know what the solution is so they'll just give you answers to questions that um that they think you they think will direct you to what they think the issue is so you'd have to be careful and question more than one user if you can identify symptoms determine if anything has changed normally there has been a change almost always not every case but almost always approach multiple problems individually so dividing conquer kind of approach okay question the obvious it's nearly always something that's pretty obvious I've seen people waste a lot of time and energy troubleshooting less likely issues when it's almost always the most obvious thing that's wrong consider multiple approaches an example is a top to bottom or bottom to top using the OSI is it an application problem and then moving down or is it a physical problem moving up and it depends on what the users are telling you and what the symptoms are obviously I mentioned divide and conquer and this all depends on your network really but it could be um dividing it into Hardware all Hardware or and all layer 7 issues or all cabling issues something like that it just depends all the Divine and concrete could be segments in your network so looking if a particular vlans affected or all vlans test the theory once it's confirmed and determine the next steps to resolve the problem for example if it's an email issue then try sending an email try it from a different users um device to see if there's more than one person affected if the theory is not confirmed you start at the beginning plan of action obviously and if you can fix it there and then fix it if it's requiring a network downtime then you're going to need to schedule an outage if you're working on a production Network again and generally this sort of issue is decided by this seniority manager or network manager potential effects what's going to happen is it going to cause make the problem worse is it going to fix it is it going to cause a different problem somewhere else when you implement the solution escalate is necessary again you normally need verification of somebody else a senior manager that this is um the correct course of action verifiable system functionality speak to the user who actually logged the issue and see if it's resolved for them and whoever else was experiencing it if applicable Implement preventative measures document the outcomes findings and actions this is basically useful if somebody else deals with the same problem I know when I worked at Cisco attack you could often put in error messages and similar things or look at certain model numbers and you'd often find somebody else that had the same problem and you could see how they fixed it or if they'd established that a bug had been found and then if that bug's been fixed in another iOS all right so pretty Common Sense stuff hopefully but we've put it into writing now so you've got uh some sort of method to follow I'd identify the problem establish your theory test it plan of action implement the solution verify document you need to write that down a few times you get the correct order in case it's a drag and drop type question all right so that's the end thanks for listening [Music] thank you foreign network security security fundamentals in the last lesson we discussed managing a network and administering a network this ranged everywhere from troubleshooting to speed optimization and in this lesson in the next four modules we're going to discuss security now just like with a plus we talked about networking and Security in network plus we're going to talk about security with the understanding that there is a whole other certification and a whole other lesson that revolves specifically around this uh concept so we're just going to sort of brush over the important things that we need to know in a network Plus or network Administration environment so to start us off we're going to talk about the basis of network security and the fundamentals that we're going to discuss in the next three modules so this involves discussing network security and identifying exactly what it is when we talk about the basics then we're going to go over some of the things that are fundamental to having a secure network these include keeping the network up to date strong passwords having a secure VPN virtual private Network administrating user access in a proper way and making sure to remove any inactive accounts now the reason I focus on these fundamentals are these are the things that we'll see on the network plus exam now the word security means the same thing just about anywhere you look when it comes to homes it may refer to Locks and alarm systems but when it comes to networks it refers to a lot of different methods but the concept is still the same the point of security regardless of where it is or what it's protecting is to keep the threats out and the valuables in think of a bank vault the door to a bank fault is a few feet thick it's made of very sturdy metal and this is because the bank needs to keep the money invaluable securely inside while also keeping the potential threats outside now if someone really wants to break into a bank and steal the money they're going to be able to what we want to do is make it as hard as possible for them to come in and steal the money nothing is beyond anyone's purview it's simply that we want to make it as difficult as possible for these thieves hackers or whoever to get in and take it now the same principle applies to network security on a network data can sometimes be more valuable than money in fact I know a lot of CEO cios CFOs out there who would much prefer that you steal some of their money rather than steal their data especially when it comes to user data or to private or privileged information because this stuff is literally Priceless this is why it's really important to have a properly secured Network and make sure that it stays that way and these are two different things securing it and then monitoring it to make sure it remains secured now it's very important to make sure that everything on the network is kept up to date when programs and patches have been used for a long time and they're well known the attackers who've had an opportunity to find holes with them begin to make use of those holes and hack through them so the longer something is out there and being used without a new version the more times attackers have to find exploits within the program or the patch this is why as Network admins we need to make sure that all the programs and patches are kept up to date programs that get used often should be updated as soon as there is a new version or as soon as a new version proves to not be buggy now when running a device on Windows the admin should always check to see if there's anything available in Windows Live update or Microsoft update which we have talked about in a plus quite a bit now usually this can install new drivers in patches that have been updated for performance and security but other things we need to be aware of are Adobe products Java which is integrated into a lot of browsers and the browsers themselves to make sure that they're all tight and secure once again we don't want to update things immediately because maybe they'll bring down the system but we need to weigh this against the fact that if a patch goes out there to to plug up a security flaw that as soon as it goes out there the hackers now know oh look there was a security flaw and now they can begin to make use of that security flaw until you update things so what we're really looking to do is balance updating immediately versus buggy Updates this is an important thing to keep in mind now it's very important that we keep another aspect of security in mind when it comes not just to our networks but to just about anything we're dealing with on devices and this is our passport our passwords people tend to think that just because something is password protected that means it's safe but this really isn't true something that's protected by a password is ultimately safer than something that's not but a password is nearly useless unless it's a strong one think about all the movies in which someone has to figure out someone's password looks around the room sees a picture types in the name of that person and Bam they're in attackers can use things called key loggers in order to log uh what passwords you are entering on your computer and then send that over to the hacker they can then take the letters symbols Etc and being used and try to piece together what the password could be depending on the attacker they might be really successful at stealing your password simply by just observing what you type in this is called shoulder surfing and it is a big problem when we think about ATMs people typing at their office and so on this is a huge problem in general but it's really problematic if you use the same password for more than one thing think about it as soon as they get one password they have access to everything especially if they get access to your email they now have access to your entire life because they can reset everything through your email so it's really important to keep different passwords for each sort of service that you access in a general rule you shouldn't use the same password for more than one thing this can end up becoming really confusing if you're dealing with a lot of different accounts that require many different passwords so there are some programs that act as basically password vaults and they require one master password to access them and then you have all of your information stored inside of those but I think some of those just have as many problems as regular passwords all you need to do is get access to the one program and suddenly you have access to all of the password programs so it's important sometimes for you to create a long random password word that can contain special characters like slashes ampersands Etc these programs can do that as well but the problem with that is we're also not going to be able to memorize that so and another important aspect of password Corrections uh protection rather when it comes to strong passwords is to use random letters symbols Etc and long passwords which are always better than short ones for instance using the password password123 is really weak whereas this one on the right which I can't even pronounce is really strong now of course the problem with this is it's difficult to memorize and if it's difficult to memorize you're probably going to have to write it down if you write it down that gives someone something to steal or you put it in a password Vault or this is maybe made up automatically but in all these cases one password can get access to all the passwords and so it's important again we talked in the previous one about we sort of have to decide whether we want to update something immediately or whether we want to update it you know after a little bit after it's been tested the same sort of thing with passwords we don't want something too weak but we also don't want something too strong that we can't remember so the best thing I think is to think about for instance a pass a code that for yourself so for instance a common one with the term password is to replace the A's with ATS and the O's with zeros if you think about creating your own password we could do this for instance let's say we wanted to turn this secure and organized into a password well I could replace the S with fives I could replace the ease with threes I can replace the A's with and ampersands and so on and so forth even an I replace that with a exclamation point or the number one and voila I've just created what looks to the plane eye as a pretty s complex password that a computer wouldn't be able to necessarily break but you remember it because you've come up with your own code of how you're going to replace certain symbols and numbers and it wouldn't hurt to throw in a couple uppercase letters there as well now with virtual private networks there's a lot that can go wrong security wise because it travels over a public network in order to collect connect to your local land and the users remotely connect an attack can happen from literally anywhere so in order to help stop attacks the admin needs to require remote users to have multiple points of identification remember in a plus we talked about having multi-authentication and remember authentication we have three different things something you know something you have it's something you are so if we're going to use multiple forms of identification maybe one thing we want to do is have a standard username and password and also a pin or security question they would have to answer these both fall under something you know we could also give them a fob key that has a rotating password on it this would be something they have it makes it more difficult if I use multiple forms of this authentication and that way it's not just things that are written down or known it's also things that are have had or even better things that you are for instance a retinal scan fingerprint voice recognition Etc the point is the more of these you have the easier it is for you to keep your stuff secure however it's also more difficult to log in and it's going to take more time so again we're dealing with time and ease versus security and we have to find the right balance because we don't want people to get so turned off by all the heightened security that then they can't use our product it also might be necessary to have a firewall between the VPN and the physical Network the firewall acts as a sort of last line of defense and if somehow an attacker manages to get through the points of identification the firewall might be able to stop them from connecting to the network based on where they are the information they're trying to transmit if they're using an unknown or untrusted IP address the firewall may be able to stop them before they connect the local area network now it's often the case that users have to access things that they have no business accessing for example someone in the graphic design part of the company has no need to access the accounting records of the company and sometimes however users are given permissions to access data like this simply because it's overlooked by the administrator so this is a huge security issue and one that's easy to fix and needs to be looked after with care the admin should only make sure that users are given only access to the data they need to do their job this is what we call the principle of least privilege now this change can be made by password protecting or it can be made using group policy meaning that we have an Accounting Group and we have a Marketing Group if you're placed into one of those groups then you're not going to be able to uh access anything except for what your group has access to now the other thing we want to do is make sure to clean up inactive accounts when a worker leaves the company the first thing the admin needs to do is to change the password to the user's account or what we call deactivate the account it'll be a very bad thing if a for former employee were to access the company's files and who knows what they could do with those especially if they were fired so once the passwords has been changed there's no way for them to access the account but it's not necessary for the admin to delete the account right away if the employee was to come back to the company soon after and needed to access their old files they could be given a temporary password and then monitored to make sure they could get their old information however if an account has been inactive for a while it should be deleted or discontinued an idle account is really dangerous thing to have on your network if an attacker is about to access this account they could easily slip past unnoticed on the network until something actually happens we wouldn't really know that there's a problem so in order to prevent this we really want to delete accounts soon as the users do not need them anymore this is why generally HR and IT talk to one another so we can make sure once we let a person go or fire someone their account is turned off almost immediately all right so these are some of the fundamentals we talked about the necessity of network security remember data can sometimes be more important than money because it's going to cost a lot of money in order to recover or make up for the loss of data we also identified some of the fundamentals of a secure network first of all we talked about keeping things up to date we talked about keeping up the firmware drivers operating systems patches to Software Etc and we're always dealing with a balancing act here are we doing things immediately or are we going to wait and possibly uh be susceptible but we might have buggy updates so we sort of want to find a good medium middle of the road solution there realizing the longer we wait the more susceptible we are to attacks we also want to make sure to have strong passwords remember a strong password generally means it's 15 characters or more the longer the better we have numbers symbols lowercase letters uppercase letters and we want to use them in a varied random combination we also want to make sure that we're not reusing the same passwords and don't write them down that's always a problem now of course again we have a balancing act here because the more difficult it is the more difficult to password rather than the more likely someone's going to write it down and so we need to also make sure that the passwords are have a certain degree of ease of use we also are probably going to want the passwords to expire every once in a while and so on and so forth with a VPN we need to make sure that there are multiple forms of Authentication remember the three things we have when it comes to authentication something you have like a fob something you know like a password and something you are like a retinal scan or a biometrics when it comes to user access we want to practice the principle of least privilege meaning you're only going to be given access to that which you need access to to do your job accounting does not need access to marketing and vice versa finally we want to make sure to disable or delete inactive accounts keeping in mind of course that someone who leaves the company might need to come back and therefore we might want to make it easy for them to have access to their old stuff [Music] network security authentication authorization and accounting in the last module we started off this lesson by discussing the fundamentals of network security Now a big portion of network security has to do with AAA or authentication authorization and accounting AAA server on a network is probably one of the most important things when it comes to security and it's quite a bit of work so in this module we're going to Define and discuss these three A's Authentication authorization and accounting in further detail so we know not just what they are but how they're implemented in a very general way authentication is the first a it's used to identify the user and make sure that the user is legitimate sometimes attackers and Bots will try to access the network or secure data by acting like they're a legitimate user this is where authentication comes into play any secure network is going to require something like a username and password to log in and any data that's really important or secure needs to be protected now there are ways of course for these attackers to gather the password and username information but the smart thing for us to do is to change passwords for all users on a network frequently probably every 30 to 90 days again we have to balance that with how easy it is for someone to come up with a new password and they're going to remember the new password they come up with we need to make sure that the passwords are documented in some way although we want to be careful again because when we write them down and document them that opens up another way they can be stolen and we want to make sure that they're all secure if an attacker has an outdated password it's going to do them no good so if we can put this in another way authentication verifies identity this is sort of like you have a ID card or driver's license that provides your identity and authenticates you are who you are one of the reasons we have pictures on our driver's license or government issued IDs is so that people can look at it and guarantee We Are Who We Are this used to be done with signatures they would look at two signatures make sure they were identical and then we could authenticate the person was actually us now we've moved way past this now we can even use things like fingerprints which more or less authenticate that we are who we say we are so here is another form of authentication you may have encountered this one before when you're trying to access things on the internet this is called or looks like a captcha and it's used to stop Bots from accessing secure data or infiltrating someone's account or making an account when we don't want them to so the text in the gray box is difficult to read for a bot it's actually a picture and it's very difficult for robots to read this and know exactly what to type in so because of this the captcha is usually made different fonts distorted text pictures Etc and it can be slightly different for a human to read but not so difficult for them that they can't actually type it in when you type in the image into here is text then you can basically ensure that you are who you say you are that you are a human rather than a bot now authorization is the next security level after authentication it's the second a so once a user has been determined authentic we've authenticated their identity they're going to be allowed onto the network but they can't just have free reign and do whatever they want we want to make sure that they can only access specific things remember that concept of least privilege well we want to make sure that the person who's on there is only going to access stuff that they are allowed to access so you're authorized to access only certain things now there are users such as the admin who can generally access a quiet deal more but we don't want for instance the administrator to have access to the partner's private email in a law firm and we don't want someone who works in accounting to have access to marketing so authorization basically provides the information on what the person or the ID person who has been authenticated is authorized to get access to now authorization procedures can stop users from accessing certain datas Services programs Etc and can even stop users from accessing certain web pages for instance we sometimes have filters that make sure our kids don't access very specific information unless they can type in a password that would authenticate that they're an adult so here's an example of what a denied web page might look like as you can see the user is being told that an error 403 has occurred other words the web page has been forbidden it requires you to log on and you have not logged on successfully so you have not authenticated who you are and therefore you are not authorized to have access to specific degree of information now users other than the administrator will most likely not be authorized to run commands in the command prompt and we've looked at this with a plus running things in an administrator mode if the user does they're probably going to receive an error that looks like this this command prompt has been disabled by your administrator the administrator can deny every other user on the network the ability to use the command prompt because they could do something that they are not authorized to do so it's up to the administrator to make sure that only authorized users can access the command prompt or do other things on the computer or on the network for instance rebooting computers accessing servers and so on now the final a we talked about authorization and authentication is accounting accounting is not the same as in bookkeeping it's Accounting in the sense that everything a user does while on the network has to be accounted for and carefully watched this is sometimes also called auditing another term that gets back to accounting in a sort of financial sense but it means something different the users on a network uh can often be one of the biggest of our security concerns most of the time someone is going to hack our network from inside rather than outside and so keeping track of how users spend their time is one of the most important aspects of network security the accounting function of the AAA servers to do exactly that it watches all of the users and monitors their activity as well as all the resources they're using these resources could include stuff like bandwidth CPU usage and a lot more not to mention what websites they're accessing and so on now some people say hey wait you're infringing on my right to use the internet but if you are at your company using your company's internet then you have signed most likely an agreement saying you're only going to use it for specific purposes and you've probably also signed an agreement whether you know it or not that allows them to monitor you while you're using the internet so here's representation of what the accounting function of AAA server does it oversees everything the users are doing and keeps track of what the resources are those users are taking up and how they're spending their time now this was a short module but it discussed the AAA and these are three really important Concepts you need to know and understand for Network plus first we looked at authentication authentication make sure that the identity has been verified this is just like in a metaphor your driver's license which has a picture ID next we talked about authorization this is what you are allowed to do this could be just like you're authorized if you have your driver's license and you're 21 and up in the United States to drink so authentication is provided by the driver's license you are who you say you are and then authorization says whether or not you're allowed to drink or even drive depending on your age and a variety of other circumstances finally accounting is basically a log of what you do if you get in trouble with the law that's put on a record that way if you're pulled over by a policeman let's say for speeding they can scan your driver's license and see if you have any outstanding warrants or if you've been pulled over in the past in this way accounting provides a background information on you and can make sure that we know what you're doing on the network what information you're accessing and also make sure when you're accessing it and so on let's say that we have someone rob our store at midnight and the store is closed well if your security card was used to get access to the store then we know that either you rob the store or someone who stole your security card robbed your store [Music] thank you network security system security tools in the last module we talked about the AAA authentication authorization and accounting there's three aspects of security are really important to running a safe and secure network but there are also some security tools and programs that prove really useful when we're trying to put these into action most notably we're going to talk in this module about firewalls and antivirus software there are a lot of other tools and pieces of software that we can use and we'll talk about these in a bit but these two come up quite a bit on the network plus exam especially because they're the two most prevalent that we see in the field especially from a consumer's point of view so in this module we're going to Define what a firewall is and then identify its importance and how it works we're also going to Define anti-virus software and identify its importance and how it works so let's start by talking about a firewall this is something you've probably heard about you might even have on your computer or on your home network a firewall is an essential part of any secure network especially in today's day and age and a network would just be at risk almost constantly without it it's basically a security system that serves as a barrier between the local network and the wide Network or VPN it analyzes the data packets that are trying to enter the local network and exit the local network and determines whether it's safe to let them in or out or not in a more General sense a firewall is set up between local private Network and a public network like the internet so internet protection is actually a large part of what the firewall is used for now the reason it's called a firewall is because if you think about it the fire is going to burn up all the bad stuff but not the good stuff as opposed to a brick wall which wouldn't let anything in so the name sort of describes what it does people often establish firewalls as their main line of defense from internet attacks and they can be configured to not allow access to certain websites as well as not allow downloads from certain websites or certain ports to be open we'll use something called a port scanner to see if there are any open ports on our Network that are going to let bad stuff in and what we can do is actually set the firewall to allow inbound and outbound ports now I know inbound probably makes more sense than outbound but if you think about it if somehow I get a virus into my computer and it starts sending information out I want to make sure to keep that information in so that I don't release any say private information about my network now the term firewall as I was just talking about comes from the physical firewalls or doors that a lot of buildings contain these doors are fireproof and they contain a fire to one area stop it from spreading elsewhere which is another way we get that term they're also meant to block out fires so this is what a network firewall does but with threats from outside and inside of the network so think about a firewall if we can use a metaphor as the moat and the stone walls around a castle everything within the castle walls is really contained and localized outside the walls however there's a public domain the internet walls in the mode of the castle are the last line of a large-scale defense before an attack can infiltrate so this is exactly what a firewall does it keeps the public network and the private Network separate from each other now the castle much like a firewall does allow certain things inside this is like the drawbridge of the castle so when the walls and the moat keep unwanted things out but then things are trusted so they are allowed in through the drawbridge so firewalls do the same thing with packets of data they only allow the ones that they trust to enter the network and we do this again by allowing or not allowing certain ports now of course one of the downsides of a firewall is it can block good stuff so for instance if I have Quickbooks on my computer and it's trying to access its download server to update the program I could block the inbound Port by accident through my firewall and um then it wouldn't be able to get updates so this is one of the issues now firewalls can be either software or Hardware you probably without even realizing it or maybe you do have a software firewall built into your I OS so if you have Windows 7 Windows 8 Windows Vista then you actually have a firewall built in now you could also have a hardware firewall which if we're talking about your home network is generally built into your Soho router that's right your Soho router contains a firewall built in and will allow or not allow certain ports to come in this awfuls us two levels of security one through the hardware and once it gets through indoor Network then we have one on our computer now like we said before firewalls are mostly used to block uh attacks from the outside but it's not the only use see there are quite a few actually as we already talked about they keep attacks out by monitoring everything that tries to enter if something isn't trustworthy it's not going to let it through now though this might be the most recognized use there are some other important aspects that we want to talk about for instance the firewall acts as a barrier which not only keeps things out but it makes sure that important things inside the network don't get out which in effect keeps the data secure this is what I was talking about without bound ports for example if secure data is being accessed and taken from someone on the outside then we can make sure that the data can't get out through our Network it's going to be stopped just like containing the fire within the building this is really important to businesses and organizations where data really equals money or more than money now for individuals it can help secure important information like your social security number credit card information Etc these aren't things that you want in the hands of attackers so a firewall can actually prevent these problems that an attack might cause just as a matter of example I'm here in Windows 7 and let's go ahead and check out the Windows firewall now I actually have two options here one is far with Advanced security and the plain old Windows firewall if we go into plan we'll win this far well you can see the firewall is on and it's working on this network and if I go over here I can choose whether or not to turn the firewall off or on now if we go to those advanced settings I referred to earlier you can see that I have inbound rules and outbound rules there are inbound rules that allow and disallow certain information for instance this rule which says file and print sharing Echo request allows the connection to be made for icmp packets which is basically for Ping now I can choose to disable a rule or create a new rule for instance if I have a specific program or Port that I know needs to have access you remember the ports that we talked about previously and this is an example of how you would use that now I also have outbound rules so for instance instead of allowing information into the system I want to talk about information I want to let out so for instance Windows Media Player has a number of rules that are here notice that none of them are enabled so if we were to check this one out for instance it says there's an outbound rule to allow the sharing service for a Windows Media Player now I could enable this and that would allow it to occur but because it is disabled to this moment it's actually not going to allow any of that information out so this is how very quickly the firewall works on your software but it would also work the same way if you had a hardware device too you can also have it monitor what's going on so for instance this is telling me that the inbound connections aren't matching a rule so that I could go in and check out exactly what that is and it's also telling me I can see all the active rules and so on that are going on here now here's an example of what a fire mole might do as you can see it's separating the WAN which usually would be shown by a cloud which we could call the internet and the users on the WAN have to be authenticated and allowed before their go past this firewall this is useful because an attack could very possibly infiltrate the WAN and try to get access to the local network but if they're not recognized not given permission by the firewall they're not going to be able to enter the land sometimes what we'll also have is a separate Network that they'll be allowed into that's sort of not between the firewall in some cases even if I erase this we'll actually have two firewalls one which allows a lot of stuff in and creates sort of a demilitarized zone which then we can either put a test server on or a test computer sometimes we'll call this a Honeypot will allow a lot of stuff in through the first firewall and then when the hackers find stuff they're going to start attacking this Honeypot Honeypot being sort of like bees go into honey we can then see what they're looking at what they're trying to get access to Etc and this gives us a sense of testing the network security then once they get into the demilitarized zone they have to pass another set of protocols to get in to our Network and as we mentioned there might also be firewalls on each one of these computers if you can pardon my awful drawing so we're going to have software firewalls just like we have Hardware firewalls in fact this might be a device or it could be a server with firewall software built in now anti-virus software is everywhere and there are more companies and softwares that protect against attacks than you can count some of the ones you might even know are for instance McAfee and Norton two big ones there's also AVG which offers a free one Trend and the list goes on and on and on now in general most of the software is pretty similar and they all do the same types of things some more expensive than the others some are more for Enterprises they have a server set up so you could monitor your entire network without having to go to each individual computer but in effect they all do the same thing so although a firewall is a really good resource against attacks there's nothing it can do once the attack has already taken place once the system is already infiltrated so attacks are not always obvious and sometimes attacks are so subtle they happen right under our noses you might not even know you have a virus until it's already done damage so even though firewall protects the attack it can't get rid of the malicious things that have gotten through this is where antivirus comes in this software has many functions one of the more important ones is that it offers real-time protection the software is constantly on the lookout for attacks and malicious things software that doesn't look right and firewalls merely block the attacks whereas antivirus software will go after an attack before it goes before it can get through the firewall now uh this software can also scan for viruses and remove them once they're found now sometimes this can be tricky because just like if I install the antivirus software after the virus has infected my system the viruses might not be found by the virus software it's also going to look at suspicious files and data and place them into what we call the quarantine the quarantine just like the name is a place where we're going to put all those files that might be infected and that way we can make sure that we can look over them as an administrators see if they're infected and either delete them or bring them back into the network finally antivirus software is going to update itself constantly if you imagine that viruses and hackers are constantly doing their work to keep everything up to date well then you probably have an understanding that we need to keep the antivirus software up to date just like every year we have to create new uh vaccines for the flu and so on we want to make sure that the antivirus software is kept to date this is generally what's referred to as data files or dat files and you used to have to download these off the internet and install them now this happens usually automatically just like Windows update but we need to make sure the setting is correct so that it allows itself to be updated automatically so just to recap we talked about a firewall remember it works with inbound and outbound ports it's going to allow some good things and good things out but it keeps the ins the bad stuff out and the good stuff in we're also going to identify we also identified rather its importance talking about how we can have several Hardware and software firewall Solutions and again we might have to manually edit the inbound and outbound ports to allow for instance a software program that uses its own port to get out and get updates one of that software that might need to go out and get updates would be our antivirus software which is what we talked about this is software that does not it can prevent an attack but it can sort of take over from where the firewall stops whereas a firewall can't stop it once it's already started an antivirus software program can go a little more in depth it has to be kept up to date and it might not necessarily be able to remove the virus but it will put the virus and the files that it has infected into a quarantine so that's really what's important about it and if you've been working on a computer at all in the past 15 or 20 years you've definitely had to use this and nowadays actually Windows requires that you have a virus scan on or it will actually bother you in the notification center quite often so now that we've talked about this let's end by talking about how we can protect our data in a very raw sense called encryption and cryptography [Music] network security encryption and cryptography 101 so to round up our discussion of network security I want to talk about the way that we secure data at the source and this gets to basically encoding the data that we send so even if it's captured or sniffed we can't allow the hackers to figure out what it is that we were sending in the first place and so this gets to encryption and cryptography just like code breaking from World War II or from our military when they would send encrypted messages and because this is a pretty in-depth topic we're only going to cover this broadly so first we're going to Define and discuss cryptography and then we're going to Define and discuss encryption including the difference between plain text and ciphertext one being the way that text is sent if we don't add any encryption and the other one if we do add encryption and then public and private Keys sort of like decoder rings for how we can read the ciphertext the public and private part comes about in the way that we have the sender and the receiver decode and encrypt certain messages finally we'll identify examples of both and how they work now this entire subject gets a lot more in depth if you go into Security Plus and the CompTIA Security Plus certification so here we're just covering this in a sort of very broad sense there are people whose entire jobs it is to Simply deal with this aspect of networking so in a very general sense cryptography is the practice of securing information using codes in order to keep adversaries or hackers or outside folks from understanding it now the word adversary generally means an enemy or an opponent in this case it just means someone who would want to intercept the information you're sending it's very likely that this adversary is your enemy quote-unquote such as a computer hacker and although cryptography is not only used in Computing in fact it's been used throughout the world even in the United States and Military Etc it's used quite a bit here in networking and it's used a lot in how we package data into packets so cryptography simply means writing speaking communicating in code this practice dates back to the time of Julius Caesar and quite possibly even earlier than that Caesar used something that's referred to as the Caesar Cipher which we'll look at in just a second a cipher is a way to encode and decode data so Caesar used it to send messages and commands that needed to remain secret we were also used it in the United States during World War II uh the Japanese used there have been a whole bunch of movies about this cryptography and ciphers play a large role in communication especially when we don't want our enemies to know what we're talking about this was true all over the world people began speaking over the radio writing in codes in order to keep information secure so a language like the English language might be a form of cryptography to someone who speaks Spanish if they don't understand the language However the fact that there is a dictionary out there that translates everything for them means that the code is pretty easy to break so what we're really talking about and what the Caesar code did for instance is replace um every a went down three numbers and replace it with a d so whenever you saw for instance uh the word Apple we would add plus 3 would be our code and so if we went down three if we wrote this out from a is b c d from p is QRS from L is M N O and from E is fgh so if we were to write Apple in the Caesar code this is what it would look like and that's because if we went back three for each of these we would get the word Apple now there was only one code that remained unbreakable in World War II and it was used uh by the US so the Japanese could not intercept messages that were being sent the US actually Enlisted the help this is a really interesting fact of Navajo Native Americans in order to help them transmit messages and these Navajo code talkers spoke a language that was so dead and was only spoken by very few people that every U.S major base had a Navajo code Docker with them and they would translate messages and send them over to each other it was never cracked by the Japanese there was even a movie about this so this is how cryptography worked right if we have a language that someone doesn't understand then that is a form of cryptography fee there's no dictionary in this case of the Caesar code all right this is what he did and uh if we want to look a little bit closer at how that worked we can see the Caesar Cipher basically every letter in this case we're going back three uh it was in the original text and then you would go back and so a became x b became Y and so on what we did earlier was actually go forward three so whatever it was we could figure out what the code would be simply by minusing or adding three so for instance if we were to write ABC right now in the Caesar code with a minus three it would turn into x y z this is a really simple code which is why it's not used anymore now we have a much more intense codes that are used now compared to cryptography encryption is the practice of putting important and confidential information into a code that can't be accessed by unauthorized users encryption is basically the use of cryptography as you can see by the word here so encryption is usually used for information that we want to keep as a secret or that's someone we we want to make sure is not going to get out to other people now a lot of times we're going to use encryption with not just regulate and we're going to add higher end encryption to stuff like credit card numbers Social Security numbers Bank information Etc so encryption is really just a part of cryptography cryptography is broader encryption happens with the data that is being sent through a network so like cryptography and encryption encrypted message is coded and appears to be complete nonsense to someone who doesn't know what the code is now the data is run through an algorithm in order to place encryption on it then on the other side the reverse of the algorithm is used to decrypt the data and an algorithm is a mathematical equation that can be used for several different things for instance in the Caesar code the mathematical equation if we had X as the uh plain text and Y as the cipher text or the text that had a code added to it we could say that if we took the code it would equal y plus 3. so if we had x y z and that was our code and we added 3 to that then we would end up with a b c and so that's how that all sort of works now encryption in an algorithms are a lot more intense than the one I just sort of laid out and they're used not only to code data but also to decrypt it or unencode it in a way that can't be read by our adversaries or people outside of of ourselves so through the encryption process we come across around two different types of text that I just pointed out first there's plain text this is the unencrypted data at this point anyone can read what it says because there's no code on it then there's ciphertext which is the encrypted data the data that can only be decrypted using a special key or using that special algorithm so in the world of encryption there are normally two different types of keys or algorithms in other words that come into play first there are what are called public Keys these are generally used in some cases to encrypt the data these keys are known by both parties that's why they're public they're put out on the web or they're sent out by email or something so everyone has it and these keys are known by both parties so that in a data transfer they can be used to encrypt the data now in most cases the and receiving the data receives the public key also so if I'm sending you uh an encrypted sort of message I'm going to send you the public key along with my data now the way that encryption and decryption will work is the same way these public Keys run plain text through the encryption algorithm and they Place coding on it now private keys on the other hand are usually only used to decrypt the data so I will send you my public key you will encrypt a message send it to me and I can only decrypt that using a private key which only I have and so this is basically how the whole system works now there are different types of uh encryption systems somewhere both sides have to have public keys somewhere we have a private key again I'm not going to get too in depth with that right now because this really gets into more of security and Security Plus but the important thing to realize is that the public key goes to both parties whereas the private key which is only used usually to decrypt the data is only held on to one person so I could anyone can encrypt the message but only someone with the private key is going to be able to decrypt the message so if we take a look at how this works um company a needs to send data to Company B but it's really important information that needs to be secure and encrypted so Company B sends the public key to company a company be created this public key so that the encryption and decryption would work with each other now company a uses this key to encrypt the data then sends it to Company B and Company B uses the private key that only they have in order to decrypt the data now you can only encrypt in this case with the public key and you need the private key in order to decrypt that's how this works but the way that company a got it is because Company B sent the public key over to them all right so just to recap we began by defining And discussing cryptography cryptography again is basically having a code of some sort uh we use codes in all sorts of ways we talked about the Navajo Indians using codes during World War II and we also talked about the Caesar Cipher which basically just means adding a certain number two uh letters so for instance if I have plus 2 as my Caesar Cipher and I want to write the letter A instead I'm going to write the letter c because it goes a b c right there are two added so then if I sent this C to someone they know oh I can subtract two from it and that's my Caesar Cipher now we also defined encryption and encryption is actually the process of doing all this we have the code we have the cryptography and then what we want to do is actually encrypt the data using it now we talked about two different things plain text and ciphertext plain text is the data before we apply the code to it ciphertext is after we've applied it to it so plain text anyone can read ciphertext only those people with the code breaker can read or the keys we also talked about that in a public and private key public keys are sent to everyone so everyone has access to them private keys are only held by one party they are private now generally speaking public keys are used to encrypt whereas private keys are used to decrypt so anyone can make uh a message that is in ciphertext but only the people with the private keys can actually decipher it and then we talked about some like examples of using this for instance not only the Caesar and the Navajo but we also talked about wanting to use it for Social Security numbers passwords are a big one and of course today's market with all the finances going on bank and credit card information [Music] network security IDs IPS implementation in the previous lesson we talked about different aspects of network security now because this topic is so encompassing we're going to continue on with this network security in this lesson where we're going to focus specifically on two types of security one is IP security which we'll talk about in the next module and in this module we're going to talk about intrusion detection prevention systems otherwise known as IDs and IPS these are pretty important and come up a bit on the network plus exam which is why I want to commit an entire module to them so we're going to begin by talking about an IDs or intrusion detection system notice the D there and we're going to talk about the two different types of IDs that exist one is behavior based and one is signature based we'll discuss what this means in a bit we're also going to Define and discuss ips's the difference between an IPS and an IDs is where an IDs is an intrusion detection system and IPS is an intrusion prevention system notice the difference between the D and the P one simply notifies you the other will actually prevent we're then going to discuss the importance of having an IDs IPS and in some cases we will have devices that do both and we're then going to discuss very briefly implementation now of course just like anything we're going to look at this from a mile high view so this isn't the in-depth the detailed version this is the broad overview now an intrusion detection system is software or network device that's used to detect again remember that word d detect attacks or intrusions that are made on the network the attacks that it detects are then reported to either the administrator or to a threat log sort of like the Event Viewer if it logs the information first it then alerts the administrator so the administrator can look into the issue now while IDs are up to date and make alerts as soon as an attack occurs they are still referred to as passive the reason they are called a passive security system is because they don't do anything to actually prevent the intrusion from stopping all they do is they passively notice that it's occurring this is because again they merely a detect the attack they don't do anything to prevent or combat it now there are a few different types of intrusion detection systems but I want to focus specifically on two different types the first is called a behavior-based system this makes alerts and reports of attacks based on the behavior that they deem to be suspicious or out of the ordinary these unusual behaviors can include large amounts of traffic policies being violated um and even people attempting to access things that they're not supposed to now a signature-based system detects the Rest by reading their attack signatures just like a virus scan program has a signature remember those data files we talked about that tells it what to look for in a virus intrusion or attack systems have a signature and a signature file that they can look at that lines up with the signature of an attack or an intrusion so signature based systems scan the signatures of known attacks and when it detects one of these signatures attacking its system it makes an alert to the administrator or reports it to a log so again the signature is based on more or less a history whereas behavior is based on what we see they're looking at two different types of attacks and there are the pluses and benefits pluses and minuses rather of both but you can see Behavior again is looking at a more all-encompassing General sort of view where a signature based is looking at previous histories of attacks and aligning the upcoming or current attack with that so here's how an IDs Works an attacker shown on the left sends an attack through the internet in order to access the network of the local app area network the attacks go through the internet towards the network now in between the internet and the firewall is this IDs and what it does is it detects the attacks being made and sends an alert to the administrator though it doesn't do anything to block the attack this is okay because the firewall is still set up to handle the attack so the attacker comes in isn't able to access the information but the administrator is still alerted that there is an issue going on and in case the attacker begins to double their efforts the administrator can sort of get on it and make sure that nothing is going to get through now similar to the intrusion detection system and intrusion prevention system also detects attacks that are targeting the network however intrusion prevention systems not only detect the attack they also prevent it from happening and causing more issues on the network these are considered more reactive or proactive software or Hardware because ips's do a lot more than ids's do they're reactive in the sense that if an attack is attempted they're going to block it from entering the network just like uh a breaker box is going to sort of kill the circuit by breaking by switching the breaker before the electricity can do any damage to the wall a ips's might even kill the connection out to the internet to stop anything from happening they're also proactive because certain ips's are going to seek out attacks and stop them before they even make an attempt on the network uh for instance scanning for ports in this way an intrusion prevention system is more expensive than an IDs but this is because it does a lot more to provide safety for the network rather than leaving the job in the hands of administrator who perhaps isn't even on site at three in the morning the IPS is going to handle the attack and prevent the attacker from connecting to the network and IDs only alerts the administrator and does nothing about it for this reason ips's are more expensive neither system is exactly cheap and ips's can sell for maybe even fifty thousand dollars depending on how versatile it is so here's what an intrusion prevention system looks like as you can see it's pretty similar to the IDS but with one major difference it's that the intrusion prevention system is actually going to stop the attack from taking place it still sends an alert out to the administrator so the administrator can take care of this but it actually stops the attack in its place and makes sure that nothing is going to occur whereas the IDS is going to rely mostly on the firewall to add Prevention Services again this is a lot more expensive but if my network has a lot of stuff going on in it I probably want to spend the money in order to provide more security for my network now there are a few reasons why implementing an IDs or IPS is beneficial first they're going to help provide additional security to a network the more security we have the more one of the important words we see a lot in computers the more redundancy we have the better adding layers of security and IPS and a firewall for instance is like wearing multiple layers of clothing in the cold the more layers the more protected you are now firewalls and Antivirus systems are great but they are flawed in that they're not able to handle every type of threat ids's and ips's can detect and take care of threats that might not otherwise be found by the firewall or by the virus scan program so there's really not a single system or program that can protect against all attacks but the protection features of multiple different types of systems can actually add up to very thick layers of protection for an attack finally the IDS IPS keeps a record of all the attacks they detect this comes in handy because it lets the administrator see where on the network they're being targeted most and then allows the administrator to make changes add protection of the places that are attacked most often and most importantly create new policies that are going to prevent security breaches in the future now while I'm not going to get into the technical aspects of implementing these systems as I said I want to talk about what we need to consider while we're considering putting in an IPS or IDs first we need to figure out the ideal placement of the IDS IPS on the network this means figure figure out where the sensors are that are going to provide the most coverage an IDs IPS needs to be set up where choke points are available a choke point is a strategy that involves narrowing down the physical space that an attacker is able to utilize and The Logical space as well this way the defenses must easier so we're really limiting the area of our vulnerability much like Achilles heel using choke points is actually something that's been in militaries throughout history notable is like the Spartan Army of 300 men which it used against the Persians when they were greatly outnumbered by forcing all of the attackers into a smaller path so if we had a mountain right and we make sure that everyone's coming up through this path then we can really attack them a lot easier from Atop The Mountain rather than having them come all around the mountain next the administrator needs to fine-tune the alerts the IDS and IPS outputs so that they are more useful if the alert merely says an attack is taking place this doesn't give the administrator anything to go off of the alerts really need to be detailed and tailored to exactly what the administrator needs to know this is something that has to be set up and tested by the administrator once the alerts have been configured and once attacks start taking place next the monitoring of the alerts needs to be handled what use are the alerts if no one's seeing them the administrator can't always be on the network constantly looking out for the alerts they're sent so it's their job however to set up a way for the alerts to be monitored this might involve hiring an employee to monitor it constantly something we used to call beeper Duty where someone was always on 24-hour call or configuring a way for the administrator to get alerts remotely say a text message finally procedures need to be put in place for what's going to happen in the event of an attack the question what's our plan of action needs to be asked just in case an attack goes on so we know what is going to uh what programs are we going to deploy what Hardware do we shut off our connection to the network Etc if an attack happens it's really up to the administrator to lead the defense and the strategy around that defense so just to recap we first talked about an intrusion detection system and remember that D is really important which is a passive system because it simply detects an intrusion as it's occurring and notifies an administrator we also talked about the two different types of IDs as there are behavior-based and signature based behavior-based looks at behaviors such as high traffic people accessing things they shouldn't be or areas being accessed that aren't normally accessed whereas signature based looks at historical data in the form of signature files and tries to match these up with known attacks of course if the attack isn't known then it's not going to be available in the signature and so this is where a behavior would come in play we also talked about ips's or intrusion prevention systems which are proactive because they might search for vulnerabilities in the system such as looking for open ports and reactive because they actually stop an attack in its tracks or at least they attempt to now the importance of IDs and ips's is added or extra security just like as we mentioned having multiple layers if you're going out and it's cold outside it's also important because we want to know how to alter our security policies over time to make them more secure and when we talked about implementation from a very Broad View some of the things we talked about is placement we want them remember in areas called choke points meaning we want to limit the amount of areas that are outside network has access to to the inside we also talked about monitoring and how we get notifications which in some cases needs to be through text messaging or email or anything else finally we needed to talk about what we do a plan of action in case we actually have an attack occurring [Music] thank you network security ipsec and ipsec policies having discussed intrusion detection and prevention systems which are mostly having to do with keeping attacks and malicious software off our Network I want to talk about something called ipsec or IP security which is a sort of group of protocols and policies that are used to keep the data that we have secure on a network whenever we talk about security there's something called CIA the CIA Triad that we need to keep in mind C stands for confidentiality meaning only the people we want to see something actually see it the I stands for integrity meaning what we send is what the other party receives it hasn't been tampered with and finally we have to balance all of this against availability it doesn't matter if something is super secure if no one can access it so broadening out into this that's where ipsec comes into play so we're going to talk about ipsec defining And discussing what it is and then talk about two protocols that we focus on with ipsec ah and ESP we're also going to discuss three different services that ipsec uses or serves one is data verification protection from data tampering again getting into that integrity and private transactions going along with that confidentiality all of this supports availability and the reason we have ipsec is to make sure that in our security we have available data finally I want to talk about some of the policies the ways that we use ipsec so as I mentioned a good amount of the security measures that we use on a network are used to prevent attacks and shield the network from viruses and other malicious software but not all security measures are used for the preventions of this malicious stuff some are intended to keep data and Communications secure within a network while preventing attacks is certainly a part of this there are some security measures that exist to establish secure and safe communication paths between two parties this is what IP security or ipsec protocols do they're used to provide a secure channel of communication between two systems or more systems these systems can be within a local network within a wide area network perhaps even over a virtual private Network now some people might think that data traveling within a local network is secure but this is only sometimes true imagine that someone has hacked into our Network and we're sending data across it well now we want to make sure that the data itself is secure so while the entire network might be protected by firewalls antivirus IDs IPS there might be nothing protecting the actual connection between the two users generally the data that gets sent across the network is not really heavily protected or didn't used to be so people tend to think that just because their network has a shield around it everything inside it is safe as well but this isn't the case it's important to have ipsec protocols in place to secure the data sent and the connections made over a network both local and wide area now there are two main protocols that are categorized in ipsec they are ah or authentication header and ESP the encapsulating security payload let's talk a little bit more about what these are as the name States ah or authentication header is used to authenticate connections made over a network it does this by checking the IP address of the users that are trying to communicate and make sure that they're trusted it also checks the Integrity of the data packets that are being sent in other words is this the data that we actually intended and was it received properly the other one encapsulating security payload or ESP is used for encryption Services which I think we've talked about it encrypts data that's being sent over a network using ah to authenticate the users ESP will only give the keys to the users that have been authenticated so I make sure to authenticate using ah that this is the user I want to give something to and then the ESP does the encryption for the people who have been authenticated providing Keys only to the people who meet the first condition now if this seems like a broad overview of these two it is we're not going to see this a whole lot on the network plus exam maybe one question but it's not really worth going into depth because that's what Security Plus is going to do and when you talk about Security Plus you're really going to talk about these nip Security in more depth then and there are a few benefits and services that ipsec protocols provide the first service is data verification this service ensures that the data that is being sent across the network is coming from a legitimate Source or legitimate place they make sure that the end users are the intended users and to keep an eye on packets as they travel across the network the next service that ipsec is going to provide is protection from data tampering again that integrity service make sure that while data is in transit nothing changes this could mean the data somehow becomes corrupted or that someone literally tampers with it again while ipsec protocols provide secure Communications within the network they don't actually stop an attacker from entering the network so while there is a chance of an attacker on the network they can't tamper with the data as it travels through because ipsec is going to make sure that doesn't happen finally ipsec provides private transactions over the network this means that data is unreadable by everyone except the end users this is where that authentication comes in and where confidentiality comes into play for example if Mike and Steve have to send some private banking information to each other the service makes sure that Mike and Steve were the only people who can read it this isn't happening at any level that you can see it's happening all within the protocols that already exist when we talked much earlier about ipv4 versus IPv6 one of the great benefits of IPv6 is it has all the ipsec stuff built in so all of this is happening automatically within our new version of IPv6 it's not even something we need to really worry about just something we need to know is taking place so we can be a little more sure that our data is actually being secured so here is what ipsec might look like if they were connecting two lands to make a Wan though the two networks have their own firewalls and Protection Systems they still have to connect the Republic Network which we know isn't the safest thing this is especially true in the public network is the internet Now using ipsec the two lands are going to create a tunnel of communication through the network or through the internet this tunnel is secure and only accessible by people inside their Network the is ipsec tunnel by the way is what we're referring to when we talk about VPN or virtual private Networks so when we set up ipsec the service doesn't just configure itself necessarily there's some things that have to be put into place for the services to run properly these are called policies and policies is what configures the services that ipsec provides they're used to provide different levels of protection data and connections based on what in getting what is getting passed through them in other words just like with passwords we have the passwords and we know they're built into windows but unless we set some sort of policy that tells the users how their passwords have to function they may not be used very well someone might just use the password password which isn't even a safe password so we have a password policy that ensures that people have a certain length uh history and certain characters included in their passwords the same thing sort of goes with ipsec now there are some important elements that we have to address when setting up ipsec policies first we have filters that are put into place the filters determine which packets should be secure and which can be left alone now every filter addresses a different type of packet so there's generally a good amount of different types of filters all of these filters get compiled into a filter list where the administrator can easily change and reconfigure the filters to address the needs of their Network now again the reason we're going to want to have filters is because the more security just like the more layers you have on if it's cold outside the more data it takes up and the longer it takes to decode so the less security we have the faster the data is going to travel but the more security uh the less easy it is to tamper with so we need to weigh this stuff like browsing on the internet might not be something we need to secure a lot whereas we probably want to secure uh for instance email a lot more or even Bank Social Security numbers etc etc next policies have to be provided the proper Network information this involves what security map methods connection types and tunnel settings are being used the security methods are basically algorithms that are used in encrypting and authenticating the data connection types determine whether the policies are going to handle a local area network a Wan or a VPN in other words ipsec needs to know what type of connection I have here so it knows what level of security to put into place you can imagine that with a wide area network or VPN we need more security than with a lan all right so although this might have been short duration we covered a lot of important things first we talked about the fact that ipsec exists remember ipsec stands for IP security and it's really not its own protocol what it is is a series or a group of protocols Services Etc that ensure security over the IP protocol or the Internet Protocol we also talked about two of the ways we do this one is the ah protocol and one is the ESP protocol remember ah stands for authentication header as the name implies it's a header in the IP packet that authenticates to make sure the users who are about to communicate are the ones for whom it's intended and who are sending ESP on the other hand which stands for encapsulating security payload is literally going to encapsulate the data in an encrypted form and it'll only release this encrypted information to someone who has been authenticated to receive it and remember to do this we use Keys both public and private we also discussed the three different ipsec services that are provided including data verification which ensures that the data packets being sent are coming from legitimate places protection from tampering which ensures the integrity of our data that it has not been tampered with either tampered with from say an attacker or the data might have just become corrupted finally we ensure that we're having private transactions meaning that the data is confidential between only the people who need to be having it and lastly we discussed ipsec policies some of the things that we need to have when we're creating our policies for IP security for instance we need to know the type of network we're on and also filters so that the appropriate level of security can be applied to the appropriate type of data [Music] welcome to module 14 lesson 1 denial of service so we're going to look at what is denial of service by the way this is a small uh subset of what you would get in the competitive Security Plus exam and and the network plus um sorry the CCNA security exam those are the vendors do security as well obviously like a juniper but um company is a good foundation and then in Vendor specific Cisco CCNA security is excellent you probably I think you need to do the CC and a first or at least one of the CCNA exams the um icnd one would do check so what is it bandwidth attacks connectivity attacks common types of denial of service attacks what is distributed denial of service types of those difference between a denial of service and distributed reflective dos attack and then types of reflective unintentional [Music] physical infrastructure attacks and how to prevent how to identify denial of service attack just bear in mind this is an overview so you need some fairly specific training on um hardening your network and also identifying and troubleshooting and resolving the denial service attack so what is it basically refers to an attack on a computer network to make its services unavailable to legitimate users you've heard of it I'm sure in the Press um before some big big companies have been attacked before Delilah service basically attacks the network with useless traffic it's a type of cyber threat so what do the denial attackers actually put their effort into doing preventing um legitimate users such as members of the public or employees from accessing Network Services emails websites online banking Etc usually the denial of service attacks occur when the attacker floods a particular network with a huge amount of traffic so for example to access a website we type in the URL you send a request to the web server web server can only process a limited number of requests at a given time now there's a whole bunch of things that can go on for example uh load balancing and then CDN cloning the uh website copies all over the web but even so and there's only a finite amount of resources dedicated to all these Solutions and they can be used up when the attacker burdens the server we're too many requests the web server is unable to process the legitimate ones as a result you can't access it and that's called the denial of service good you can then Google denial of service attacks and look at all the news stories over the past few years and messages to establish a similar attack only limited the number of emails are allowed in your corporate accounts usually mind you even large um free providers like Gmail have got a limited amount of um storage so as a result the attacker can stop the users getting legitimate access to their account and in an email bomb the denial of service attack the attacker send a lot of spam emails and they disable the actual email server rather than just an account on the server generally not concerned with stealing information it's just quite an aggressive way of bringing down a particular service it could be a person a business or an entire company they can attack and Destroy files in affected computer system or Network and some situations the Denali service stack actually affects the website um accessed by the users most uh denial of service attacks are aimed at the computers Network bandwidth connectivity our resources also server resources bandwidth attacks on the computer or network with a huge amount of traffic huge burst of traffic legitimate users can't access every network resources the connectivity attacks harm the computer with a large amount of connection requests available operating system resources are quickly consumed and the computers enable once again to perform legitimate requests another common type of denial of service attack is a buffer overflow all devices routers switches have buffers that manage a temporary excess amount of traffic send and receive buffers and if these buffers are actually overflowed then depending on how the devices are configured and what it is then it's going to cause problems and packet loss the sin attacks teardrop attack Smurf attacks viruses a whole bunch actually the buffer overflow is the most used distributes of a huge led to a network more than the um buffer is um able to handle when the attacker has awareness about the weaknesses of the target system or network that's when you'll get a buffer overflow attack and they can Target certain vendors or certain devices such as Cisco routers or uh the vendors firewalls Etc once when the attacker simply tries to attack not knowing whether it's going to work so it's a quite a Brute Force attack but for attacks are based on the system or programs above their characteristics and other way distribute emails including 256 character file names which all take a matter of amount of time to process so the huge icmp packets email messages including a from statement that is more characters than 256 seems to be the limit for emails now this is a sin and synark which you should be familiar with from the network of a plus and and the other network research you've done this is what happens before a connection can actually take place if you're using TCP so with a cell attack the attacker sends a TCP connection request faster than the Target computers processing speed using client server technology it begins to establish a three-way handshake so you'd have a sin sinach sin and there should be an acknowledgment happens before the data sent that doesn't actually happen so client sends a collection establishment using the sin synchronized message a server can then send a sin synchronization acknowledgment client responds with an act an act message and the connection is then established if the attacker sends repetitive sin packets to every port using a fake IP address the server establishes Communications and responds to all requests and what it also does is it leaves a a window open for the actual Communications to take place so for each request in request for a certain period of time depending on the traffic it will um Reserve resources replies to each attempt with a synap packet from every open port okay teardrop account attack sends fragmented packets to a Target computer when the computer receives the packets it's enabled to reassemble them because of the following a bug in the TCP fragment reassembly overlapping packets crashing of network devices can usually happen on older operating systems some of you might remember these three Windows 3.1 Windows 95 Windows NT and some versions of fair Linux some Earth attacks is where the attacker fluids the victim's computer with ping packets the attack initiates the attack by sending a ping request and then spoofs the destination address ping replies are sent to the victim's computer address since the Ping request is addressed to the broadcast address all computers in the network have to respond and um each packet is opened and checked and to see if it's the destination as a result the victim can't receive any genuine traffic because it's already flooded with ping packets uh technique of assigning a network packet with a file side P address is called spoofing computer viruses these are distributed and spread throughout the network in a number of ways the attacker uses and controls the victim's computer to attack somebody else's low and weak uh security network security and some device some devices you're waiting to have patches applied to or they haven't rebooted after up and downloading some updates or whatever and this is when they become vulnerable attacker floods they target competes with a huge amount of data to a particular site or spam emails using a victim's computer so the name distributed indicates the attacker uses multiple host computers uh this is to throw um others off the trail and make it harder to actually identify the attack because the um victims are actually legitimate systems on the hosts the attacker can increase the effectiveness using client server technology in distributed denial of service master program or software is installed on one computer normally they use a stolen login credentials now it may not happen immediately but at some particular time the master program communicates with other agent programs that install the computers anywhere on the internet when the ages receive their command they start to attack the master program is able to spread thousands of agent programs within seconds using client server technology so some characteristics of distributed denial of service attacks a botnet traffic spite coordinated attack so if you can see that there's a attacking machine at the top there and handlers and compromise systems um going down to the targeted services or servers on the bottom there so botnet refers to a group of computers that can cooperate also known as zombies in this context at the botnet owners also known as herders they manage computers in their botnet botners used to send spam emails or to participate in distributed denial of service attack so this is why it can be so difficult because all these legitimate devices at some point of time when there's a trigger it's a like a timer or it's time when everyone's off work or on a Saturday night on a bank holiday they'll start their attack traffic spy overloads the victim's Network or server in order to its services and resources as a result the legitimate user will not be able to access the service they use when people are coordinated to carry out the attack on a site or site at the same time when many people attack the server the web Server slows down or gets overloaded it's difficult to differentiate such attacks from the normal traffic where many people do this at a similar time the web Server slows down or gets overloaded uh it's difficult to identify this a type of attack from normal traffic that can happen and obviously you do get spikes on networks and then if there's updates been applied to the servers again it can um appear to be slow legitimately slow difference between denial of service and distributed and using a single internet connection an attacker can harm a network in a Dos attack launching multiple connected devices that are distributed is a distributed denial of service attack uh the distributed another service also differs in the attacks that perform using botnets um including mobile phones routers PCS Etc Denali service attacks can harm a single machine or they can attack an entire network moving on to the reflective Amplified denial of service the reflective user third-party machines to attack a targeted computer so basically the is one way for the attacker to mask their identity reflective denial service attacks use third-party servers for example DNS servers to attack a targeted computer the attacker sends a requested the reflector server or servers with the IP address of the target and what it does is overpowers the target using response packets an example is a DNS response type of reflective denial of service attacks DNS amplification Network time protocol smurfing mentioned DNS amplification the attack explicit DNS server to make um change small requests into considerably larger payloads this can be used to overthrow the victim's servers Network time the attacker exploits a widely accessible Network time servers and destroys the targeted computer with UDP traffic which is what ntp uses uh can they're not all intentional they can be unintentional this is when a server crashes for example can't provide services because of traffic from legitimate users uh again have a look there's a whole bunch of quite um well reported and embarrassing examples for government and private companies large companies so in a popular website hosted news on a less equipped secondary site the server on that side won't be able to handle the traffic especially if there's a big breaking news story going on a person physically attacks the infrastructure of an organization when it's a physical attack example is they snip or destroy a fiber optic cable again these I suppose these could be um malicious or accidental or known quite a few cases of work people cutting through cables by accident if the attack is able to access the compute system then they can obtain information on the computers obviously there's no set way to rescue computers or a network from these type of attacks you can put into place certain steps to reduce the likelihood install to maintain an antivirus on your end devices you can also have antivirus on your mobile phones firewalls and computers and configure them to control the incoming an outgoing traffic protect emails from spam they're just the latest uh hacking on the Democratic National Party actually where a guy received a link telling him to reset his password and that went off to some Russian site allegedly somewhere who then got into his system and read all of his emails and all the other emails for all of the people on the site and it will manage unwanted traffic and send alerts for spam email messages you can install a intrusion detection system an IDs that will protect systems from the distributed denial of service attacks the RDS uses collection verification methods and speak to whatever your network equipment vendor is for more information you can disable and use networks or segments or devices or ports on switches regular system performance and now you can have legitimate issues that represent denial of service like a fonty faulty network card a spanning tree issue a routing protocol convergence when you're either booty devices or a network has gone down or up and large file download by a user on the network who doesn't have a limit a bulk email sent for marketing for example unusually slow Network I know and some networks I've worked up at for example a Friday afternoon there was a big backup and the whole network went slow but if that happened on another time of the week then it could be a warning sign unreachability of a particular website High numbers of spam messages received on an email account denial of service oh we've just summarizing what we've covered is deniala service bandwidth attacks connectivity attacks common types of deniala service and what is distributed to Denali service types of distributed attacks the difference differences between the two reflective denial of service types of reflective unintentional attacks on our physical infrastructure and then preventing denial of service and identifying one when it happens so that's all for now thanks for watching [Music] welcome to module 14 lesson 1A common networking attacks we've heard earlier about a few attacks but we need to just update the list because of the new stuff in the syllabus you can look at Social Engineering Insider threats a logic bomb Rogue access point Wireless evil twin War driving could love to know who comes up with all of these names uh fishing around somewhere DNS poisoning ARP poisoning spoofing de-authentication Brute Force VLAN hopping man in the middle and then some exploits and vulnerabilities social engineering the funny thing about this threat is it isn't um electronically detectable so we don't have a little alarm go off somewhere it's um normally when an attacker convinces an employee to disclose confidential information so what happens is uh perhaps they could um say they make a phone call that it goes through to um headquarters office and then they um they asked to be put through to your office so what you'll probably see on your phone is the extension one two three four as if it's coming from here so you think it's an internal call and but really it's coming from outside here in the um the EU the hackers house wherever they may be so it looks like um uh the legitimate call they pretend to be a senior manager or someone inside the tech support department and um they'll access some information they'll ask you for passcodes or say there's a problem with your account and um this is a pretty successful way of of getting information the other thing is um or accounts are social engineering is somebody Who Walks Behind the employee who's already entered the security guard for a door also known as tailgating also another way is leaving the USB ground on the USB on the ground somewhere this is quite common sometimes this these USB sticks have actually got a battery in and it's designed whatever whatever device you plug it into sends an electrical current through it and it fries your circuit board and Fries your hard drive or it can actually plant some lines of code Insider threats normally an employee or a contractor they could be under duress working for a competitor or a blackmailer looking to get information and most security focuses on external threats so it's looking at incoming attacks malware Trojans all that kind of stuff but inside your organization obviously you could have people that are posing the threat so people who work for your organization should know your systems policies procedures and weaknesses and they should know how to spot somebody Who's acting suspiciously or acting for suspicious information as you've probably seen in the movies you could have what's known as a sleeper so we normally uh associate this with spies sleeper agents let's sleep with somebody who could be waiting to be activated obviously they could easily go undetected and they could be doing um things to your network or passing information for some time a logic bomb is a type of malware it does damage after a certain condition is met so an example is um the spyware or the the malware sorry is on your device and then when the clock ticks over to the first of the first say 2019 or whatever it then executes the it executes the code and then does the damage it can be left behind after attack and what it could do is destroy any evidence that is taking place so it could destroy whatever fires it's actually put on your system making it harder for you to do a forensic analysis you may remember the Chernobyl virus this was an example of a logic bomb they wrote to the boot sector of discs swipe the bias on the hard drives and left the devices unusable so pretty bad uh Rogue access points so we're talking about the um waps wireless access points major concern especially in large environments so somebody's brought in a third-party access point by Network user often this can happen when somebody's complaining about their signals you've got you know you've got bars on your device so you've got one or two bars then I've seen instances where people have brought in their own access points and somehow managed to connect to the network and they get obviously a higher connection or faster connection so gives a network access to anybody in range of the Rogue access point so this is the the danger of people who uh on purpose or just accidentally they don't know how the technology works a lot of other devices will be associating with this access point here when it should have actually gone off to the corporate one you mitigate this for regular site surveys basically you're walking around with um your wireless wireless device checking for legitimate devices uh you can force users to authenticate user NATO 2.1x uh also can happen if you enable Wi-Fi sharing on your phone so if you're stuck somewhere you've got your smartphone there's a little um app in there where you can let the devices say for example your laptop if that doesn't have a capability it can actually piggyback onto your um phone with a wireless signal and then connect to the network so you've got to be careful of that Wireless evil twins this is uh configure an external access point to behave as The Trusted access points it used the same SSID and their security settings so it'll all look the same and the user connects you can see the the legitimate one is here but the signal is pretty weak the signal here is much stronger so you'll more likely connect to the Rogue access point this device normally will have a quite a strong signal on purpose so it is chosen of the legitimate one again this can be brought in by Network users innocently or it can be done maliciously mitigate with https or VPN tunnels while driving is just simply this happened when Wireless first came out and nobody had security or it was just a very weak security people drove around trying to find some wireless access somewhere and um if they could see your device and connect to it even when I it wasn't too many years ago and my my internet went down and I um I could see on my wireless um if you do a wireless search you'll see a few padlocks and then um you'd have one with a open padlock and you can just you could connect to that so you see it less now because most of them are configured quite easily for security fishing email sent which is looks legitimate usually appears to be from an official website and it asks you to click on the URL so you click here the sort of things I'll see are it'll say Amazon or um text message and even smarter people have been caught out say for example if you're like me maybe every three days you've got an Amazon delivery coming or um or something from eBay so if you're busy you'll see it I think oh no I've missed my Amazon delivery too late you've clicked on it and um the damage has been done fishing can be phone based also you come to this with email security systems spun viruses fishing Etc ransomware has really been in the news lately because even the law enforcement agencies have been caught it's taken out large areas of um the National Health Service in the UK it limits all of some system access and it locks your screen as it does here until you've paid money to the extorters offers threatens to publish your data and if in the case of uh I can't remember what it was some sort of police department anyway but it accessed all of their systems somebody downloaded or somebody got an email uh opened it up and um they downloaded the software and it spread through all the all the devices often uses cryptocurrencies for payment so it's hard to trace the money I often uses Trojans uh wannacry the uh one of the latest ransomware that uh malware um software packages that came out automatically transferred it didn't use a Trojan DNS poisoning we've already learned about DNS this is a fake DNS cache entry it cropsy data inserted into your system and the name server returns a false result so you'll do a DNS lookup it goes to your DNS server but for whatever reason this attacker has somehow injected this fake entry and instead of going off to the real server here it queries the fake one and it just for all intents and purposes to you looks like you're actually on the correct site obviously then it'll try and get passwords usernames or credit card information and again this false entry here if you've got a DNS server it can actually propagate within your depending on the authority of This Server it'll propagate to other servers up poisoning requires the attacker to have access to the victim's local area network again this could be a contractor or somebody who's managed to get in somehow it provides a host of the wrong Mac address for hosts the host IP address so um if we go down here this host is looking for the you can't say it can't encapsulate the packet as we already know until it knows the MAC address so there's a field here for layer three and then but for Layer Two in order to send the packet out it needs to know the Mac and if it's got a the false entry here from the attacker then it will send it to the wrong host it'll send it to here instead of here or vice versa you combat this with Dynamic harp inspection which is you will enable this on switches our and DHCP snooping there's a lot of different type of spoofing when it comes to hacking this is pretending to be someone or something you want and one type of spoofing is DHCP spoofing the idea is the software exhausts the pool of addresses so you'll have a pool of say 10 000 addresses and it will spoof keep requesting the addresses until eventually there's zero left at which point in the DHCP server can't allocate information and then hosts on your network can't join the network uh the Mac impersonates house or device on Two Hosts on one switch Port so this is actually poisoning it looks like the port on the switch here it should have one Mac address per port but it's got two associated with the uh Port which um it can it can happen if you've got a um Hub plugged in but it would you would normally have this on your network however the ARP Source the MAC address is disguised and the arc cache is poisoned de-authentication this is used on Wi-Fi networks this is more of a pain than anything it sends a de-authentication frame to the host to end the session the attackers boosts the victim's Mac address which you could attain by sniffing while a sniffing now there's no need for encryption so even though you've got an encrypted uh connection so or your device or all your traffic is encrypted the de-authentication frame doesn't have to be so whatever that frame will say whatever whatever it says in the frame to tell it to terminate the session that doesn't have to be so it's a floor in the technology brute force uh this is a type of password attack the other type is a dictionary attack so what the Brute Force attack does it just keeps guessing over and over to try and find the password typically the username would have been installed and um yeah you'll have a hashed version of the password this is what it's trying to guess the same hashing algorithm is used for example md5 is used and it will use this to try and send hash values you'll combat it using Advanced algorithms so you'd have like millions or billions of combinations um for example RSA or public key encryption VLAN hop in uh host typically require a layer 3 device to reach under the VLAN and if I've got a picture of this actually but we've seen before if you've got a hosts in this VLAN and they will connect to a switch and then hosts in this VLAN so VLAN 10 VLAN 20 and they'll be they'll have different IP addresses but uh these do these devices can't connect to one another unless the switch is connected to a layer 3 device now this can actually be built into the switch it could be a multi-layer switch but it has to have this layer 3 capability well VLAN hopping the attacker attempts to bypass the layer 3 device to com compromise another device and you could have all your security or some of your security built into this layer 3 device here it's done by a switch spoofing or double tagging so switch spoofing the device impersonates a switch whatever this Rogue device is it's pretending to be a switch so probably we'll need a trunk link here you combat it by disabling trunking where not required to say this is your frame here and you would have your VLAN uh 10 here and say 20 here well normally when the frame reaches the destination the VLAN tag is removed because the hosts don't really care that they're in a VLAN but what they can do with VLAN hopping is they can add an extra one um here in order to gain access to a VLAN when this device might be over here on VLAN 20. so that's double tagging combat by using a dedicated VLAN for all trunk links so your trunk link between this switch here is switch here this switch here you've got a special VLAN only used between these trunk links so save VLAN 101 102 103. these these numbers aren't used anywhere else on the network they're just used for the trunk links uh this is just a diagram showing you um the double tag frame here so the switch arm removes the first tagging forwards to switch to and this time the tag is still attached to it man in the middle attack uh convinces the sender and receiver that the computer in the middle is the actual host so this host here thinks it says speaking to the server the server thinks he's speaking to this host over here really it's going between this intermediary device here which is the attacker you normally accompany this with DNS or ARP spoofing so there'd be an ARP cache here and here and it would say the back address for this particular host but really it's injected a false Mac address here and it and the messages are actually sent and received so there's acknowledgment it sends and then this device here will send out an acknowledgment but really it's going through the middle here type of spoofing attack I've renderability scanning um this should have appeared in a moment sorry it probes the host in order to find an explode exploitable service or process so you've got your server here and obviously there's ports permitted or denied but it will keep probing until it finally finds one that's open and then it will try and do some damage there's a whole bunch of tools if you do an ethical hacking course for example you can download there's a ton of free tools that um the idea is you're trying to learn how to protect your system but they're obviously available for use by hackers now say there's a particular Port open or a service so um like an instant messenger Port has been left open this will then tell the attacker the hacker what type of attack will work best on this particular Port so it may not use that specific pool but it may then be able to Target a vulnerability in the application one of the tools you could use is a nmap you obviously counteract all of this by doing some penetration testing or paying for it and here's a result from the nmap tool here and then it's giving you your your outputs you'll learn more if you do penetration testing which isn't really covered in the syllabus all right so we've covered a lot of stuff social engineering Insider threats logic bombs the Rogue access point that somebody brings in evil twin driving around looking for a free wireless fishing uh ransomware poisoning the DNS entries the ARP cache spoofing is pretending to be something or someone you're not D authentication the frames got um it can be in clear text Brute Force attacks VLAN hopping man in the middle and then exploits versus vulnerabilities that's all for now thanks for listening [Music] thank you network security threat mitigation and user education we've now talked about a lot of the different types of attacks and security threats that you encounter in today's world when it comes to your network and we've talked about ways to protect from these threats from attacks to antivirus software and so on but let's talk a little further about how we can mitigate these threats and if that word is new to you the first thing we're going to talk about is what threat mitigation means we're then going to identify some of the steps in a good protection strategy these include developing strong security policies monitoring the threats on your network something that we've talked about in the past a hugely important one educating users since almost all the threats we've talked about in some way shape or form have to do with what we call social engineering in other words getting someone to do what you want them to do for instance give them your password automating scanning and updates both from uh updates of the operating system and from the virus scan program and patches and updates for our operating systems and our software so what is mitigation one of the only ways that a network can stand a chance against attacks is to do something before the attack is made isn't it said that an ounce of prevention is worth a pound of cure well this means more than just having anti-virus and firewalls in place those things are great but they can only stop an attack that's already being made really the best way to protect a network is to set up prevention measures before an attack can happen the idiom of an ounce prevention is worth a pound of cure means that you save a huge amount of trouble by preventing the trouble from even happening so one of the best ways to do that is to mitigate the threats that are made on your network mitigation is a word that doesn't just apply to networking but in this case we're talking about it in the sense of lessening of a chance of an attack by using mitigation you're taking measures to reduce the frequency of attacks the size of those attacks when and if they take place how severely most importantly they're going to impact your network we need to have a strategy in place in order to mitigate threats and make life on the network easier so step one of the mitigation strategy needs to be to set up rules and policies within a network users are set up by the administrator and need to be agreed upon by all the high up people on the network and all the high up people in your corporation they then need to be told to all of the users these rules should be standard throughout the network with very few exceptions because these exceptions easily lead to a breach in security one of the rules that needs to be set up for instance is what can users download such as applications can they download stuff like browsers well some of them are trustable but are we going to trust people on our Network to choose the browsers that are actually worth trusting the administrator needs to be wary of just about any program that a user could download and as we learned in the last module viruses can hide within programs they don't just attack out of nowhere a user on your network could easily download a virus without even knowing it and then they end up infecting not just their computer but the entire network so a rule needs to be put in place that says whether or not downloading of applications is allowed and if it is from what sources you may even want to limit the fact that people can download by shutting off their user rights to download or to install programs on their network if they can't install anything they can install a virus another major Rule and this is really important is are they allowed to use outside storage devices such as uh removable hard drives thumb drives flash drives and storage CDs any one of these media storage devices can contain malware one of the uh classic examples is someone leaves flash drives in the parking lot when you find the flash drive what's the first thing you do oh you say it's a brand new flash drive I'm going to put it in my computer I want to test it out see what's on there see if I can find the owner well the minute they do that they've just infected your system and your network with a virus so we need to make sure that even though the person might not be trying or mean to infect the network they could do it simply because they don't understand the risks that are associated with flash drives and outside storage media they might also be bringing stuff from their home computer which very well could have a virus on it so storage devices could contain malware without the user even knowing it and this isn't something you want to risk so a policy is really important other things such as this would include stuff like tailgating when someone logs in uh swipes their card to get into a building in the morning if they open the door for someone else well now that person just got in without being audited we didn't have they didn't have to swipe their card so that's a pretty major concern when it comes to security another one uh is something like shoulder surfing or giving out your password we need to make sure the policies of how passwords are reset when they're reset and who you can give them to is fairly important if I give my password to my wife and suddenly my wife becomes my ex-wife she could do some major damage to me and to my company by using that password to get access to private information so step two is a mitigation strategy which is to constantly monitor virus threats as you might already know attackers and computer hackers are very well educated when it comes to getting around security systems This Is How They infect networks and when their attacks are blocked most of them just update the attack and try a new version they don't just stop so this is why the administrator needs to be as on top of the virus versions and attackers and the threats that are out there it's up to the administrator to make sure that they're up to date and research is being done and they're knowledgeable at the newest attacks that could be coming to their Network again it's no one else that's going to get blamed except for the administrator when someone hacks to the network so not only do we need to monitor our Network we need to monitor the threats that are out there and this really involves doing research on what the latest and greatest techniques are to hack into a network step three is user education which is really I think the most important step that we have out there it's critical to have Network users educated in this field so that they know exactly what sort of threats are out there and what safety habits are there as well there's some safety habits that are obvious like locking a device and keeping your password secure but there are other security measures and knowledge that's less obvious but just as important Network users need to be knowledgeable on how to protect themselves from viruses and how to recognize them so they don't just click on something when it pops up on their browser first they personally need to back up their important data because in the event of an attack perhaps are major system goes down alternatively they need to know that they should be um backing up their data to perhaps a central location or they need to be taught where to back up their data for instance to the network share and not to removable hard drive or not on their desktop because if they back it up to their desktop then what happens when their computer gets broken now they've lost all the work they didn't back up automatically to the server they also need to be diligent about web browsing what they download what they click and so on if they're administrator is going to allow them to download programs they need to be careful about where they downloaded them from again we always have this interval between responsibility and power the more powerful you are the more responsible you have to be if I can install things on my computer that also means a hacker could use my information to install something on the computer as well and finally if a if they download a program that seems illegitimate or they think they've been attacked they need to be able to spot the issue and report it to the administrator before the risky program has a chance to damage sometimes they don't want to say anything because they don't want to get in trouble but if they had said something earlier we could have prevented more damage it's really important for them to know when they are being deceived by something and when something is legitimate so I see this all the time people send up these emails saying beware of this and an easy Google search would show that the thing that they're actually being aware of isn't real it's something fake and they've spent time and energy everyone's time and energy getting worried about something that actually is not going to affect them on the other hand they don't seem to recognize when someone's account has been hacked and is asking for money money when that person would never do that it's not characteristic most of all they have to check and double check stuff and be willing to ask questions so here's an example of an extremely common virus that's intended to scam people out of money on the on the computer that's being infected the virus takes over your computer and only lets you see this screen or one very similar to it it claims that the IP address has been used to do very illegal things and the FBI sees the computer and in order to unlock the computer you have to pay a fine or purchase a code now this virus is extremely intrusive and obviously uh quite you know um successfully convincing look at all the 7-Eleven CVS Rite Aid all the logos at the bottom Department of Justice Etc and the reason they're gonna make you pay through money pack it looks so real is because that way they know they're getting the money on the other end so it's important for someone to recognize that this is actually fake look on here it even scares people by saying you have 72 hours to pay the fine or you're going to be arrested now someone might have been doing something like downloading uh a torrent off the internet and so they think oh my God I'm gonna be in trouble and they don't want to tell you because they think they're going to get in trouble with you as well we need to make sure that they have a judge-free Zone in which they can come tell someone and that way you could remove the virus and they could go on on their way and continue to work now as viruses and malware attacks become more and more advanced anti-virus software improves to combat them there are thousands of antivirus software and some are more advanced than you could possibly even imagine it's not at the ordinary however for antivirus software to have automatic features so step four in the mitigation strategy needs to be to make sure that antivirus systems and software are configured to do things automatically this means they have to automatically scan the computer scan the network and update themselves we don't want to rely on a human to do this very often when it comes to virus scan nothing's going to be rolled out automatically that's going to damage our computer so this stuff needs to happen automatically when are we going to scan the network well we want it to scan when no one's doing anything so we want to do it for instance at 2 am not at 2PM when people are busy opening things and closing things and that's when the virus scan program won't be able to get access to fifty percent of the network and therefore something could be hiding out this eliminates all this eliminates the human element it allows for more regular and controlled updates in the process which is important because when we allow humans in that's when errors occur finally when an update to a program is released it's generally to address bugs that were found within a previous version along with these bugs there might have been some security weaknesses in the software that need to be addressed but program updates don't come out very often in between uh updates patches and so on there might be a temporary fix that's released or a fix that is manual that have been found so a patch does exactly what you think it does it basically covers a hole in the software and temporarily repairs it until an update or a new revision of the software can come out so as soon as patches or updates are released the network admin needs to look at them and think about installing them on the network now notice that I don't necessarily want you to just install it right away I want you to test it and think about it because the patch or update could very well cause another problem on the computer and one thing we don't want to do is bring down our system because we put in a new update that suddenly stops our printers from working or something so we need to balance this with the idea that once the patch and the update is released the hacker now knows that this is something that they can exploit and so the longer you wait to update it the longer you're at risk of being exploited all right so we talked about a bunch of things in this module some of this is common sense but these are things that pop up on the network plus exam first we want to Define Network mitigation mitigation the word literally means to lessen and so what we're doing is we're lessening the threats that can hit us some of the steps that we identified in this strategy were first to develop strong policies for instance a password policy is important download policies internet use policies and so on and so forth we also need to monitor threats not just internal but we need to research what's going on around the world so we know what the latest things are that are attacking our systems the most important one I think is educating users social engineering is how hackers and attackers get around the human element when there's a human element there's a flaw and so we need to educate users so they don't click things that look bad and they know when to ask questions since this can help them as well we also want to automate scanning and updates from virus scan programs and perhaps our firewall this should all happen automatically because if we remove the human element then there's not going to be an issue we also want scans to happen in the middle of the night when no one else is using it for instance 2 am or 1 am make sure that you give enough time for the scanner to actually scan the entire system finally we need patches and updates and we want to balance the patches and the updates with uh the patch actually doing harm versus the weakness or exploit that it's correcting the longer we wait to employ a new patch or update the longer we're at risk [Music] thank you welcome to module 14 lesson 2A Advanced threat mitigation so this is new stuff for the um double 07 version of the com2 exam managing your signatures hardening your devices in terms of security that is changing your native VLAN switch Port protection restricting access with access lists Honeypot and honey net uh penetration testing so signatures in terms of signature management we're talking about IDs and IPS which we've covered earlier the signature-based detection examines Network traffic for pre-configured and predetermined attacks so the signature is the thing that is matched against in these devices the threat the threat signature these are known as signatures attacker um convinces employee to disclose confidential information if adult signature is identified by the system an alarm is triggered or the traffic will be blocked this it depends on how you've configured your um IDs and IPS so it will either um send an SNMP alert or create some sort of log message or whatever you've designed it to do the signature codes are updated or they should be updated regularly for new or false patterns you don't you really don't want false positives either because it's just going to be in traffic's blocked when it shouldn't be uh there's a website called threat threatconnect.com they offer some sort of signature management uh system for for you to look after all your signatures uh I I only suggest it because I use their graphic and I wanted to credit them for that but this is what came up when I was researching threat signatures device hardening this is part of your daily weekly monthly admin task especially if you're in charge of security for uh looking after your network you'll Pat your update software or firmware in your Hardware devices check for non-compliant passwords this will obviously part of your password policy but I'm sure you've logged into something or had an email updating you saying that your current password isn't um strong enough and you need to update it removing redundant networks and IP addresses strangely enough I've known equipment found years after people thought it had been decommissioned it's sitting in a office somewhere plugged into the network and nobody knew it was there and this can then be a back door for hackers to find and get into your network changing security keys are changing the native VLAN so the native VLAN is used for any untagged traffic on your network you'll be familiar with this when you start doing Cisco configuration or any type of juniper or the other network management big security vulnerability your native VLAN is passes important information such as um your Cisco Discovery protocol or the equivalent which is device information foreign your operating system that it's running etc etc a dynamic drinking protocol is for uh trunking so your native VLAN will normally go across a trunk link and you've got all of this important information on The Cisco devices certainly and probably a lot of other vendors the native VLAN is VLAN one and if you leave this as the VLAN that the switches can communicate with you've left a possible security vulnerability because this traffic is actually untagged so what you want to do is on any drunk leg trunk link you change it to an unused VLAN so this is one that isn't been used on um so you've got to VLAN 10 20 30 and 40. you would use your an unused VLAN on your trunk links for example um two two two just something fairly high and then another trunk link to another switch you'd have another VLAN for example two two three Etc is the output for a Cisco device and you can see this is trunk in so it's passing multiple vlans on this link but the native VLAN is uh VLAN one so I've wiped over it there the native VLAN is VLAN one which you don't want so what I did I went to the trunk interface here I issued the command switchbot trunk native VLAN five you'll probably use something higher like I said like two two but it's just to illustrate the point so this traffic that passes over uh the native VLAN will use VLAN F5 it won't use VLAN one and you've got to be careful because you can't delete a VLAN one it's there all the time you just don't have to use it to pass any traffic and now you can see it's changed from VLAN one as a default to VLAN 5. I've already mentioned all this sorry so another thing mentioned is bpdu guard this is arrived in the syllabus a bpdu guard it's on an interface the port is every disabled when a bpdu is received so Bridge protocol data unit we talked about earlier this is uh used for spanning tree traffic and it can actually change your layer 2 topologies for example let's say this switch is the root you've got a high a high-powered switch here and it would normally be a multi-layer switch here and all of your traffic is pointing to this device but what will happen is this device will announce a number to say I am the boss and say for example this is number 99. this is the number that determines the root of all your spanning tree traffic well what happens is if this device uh connects to the network say you've bought you've found it on a Shelf at work and for some crazy reason all you've done is plug it in and this has happened by the way I've seen it happen well this device could actually be configured with the number 100 in terms of um spanning tree and what could happen is then or this could be a really low switch is worth about say a hundred dollars and it's just got a tiny amount of process and power all of your spanning tree traffic all of a sudden will be converging onto this tiny little switch the CPU will go from almost nothing through the roof it'll probably crash bring you down your entire local area network and at that point you'll probably be out of a job to be honest so what happens is with bpdu guard you configure it on this interface here for example fast ethernet and 10 and if a BP do you frame is seen coming in onto this particular interface it will error disable um it will error disable it and it won't pass traffic until you the network administrator um what come comes shuts it manually and then manually no shits the interface so you have to re-enable it uh root guard so I mentioned uh if this is a topology where it's actually I think from my CCNA book where I'm telling you on what interfaces depending on the topology you would add bpdu guard root guard you would add down here on these level of interfaces so these are your layer 3 switches and these are your these images here represent Layer Two uh root guard is configured per Port so you wouldn't configure it on a device and expect the configuration to be passed out through your network and like um other configurations root ports are the closest to the spanning tree master these ports are furthest away if this is the master here in my topology these are the ports that would normally you would want to be root and it's basically saying the root equals um best path to take to the master this is not the best path to take to the master this would cause you a lot of problems this is why you would enable root guard on these ports here so Modesto for incoming Bridge protocol data units and it prevents support from becoming a root Port how it does it yeah you can learn a bit more when you do Cisco CCNA and ccmp Etc DHCP snooping this is the uh legitimate one here this is the Rogue that somebody's either somebody's attached it to your network or they've downloaded some code accidentally onto their device and it's trying to take over as a DHCP server for this segment of your network which you don't want to happen it forces the switch here to examine and filter inappropriate DHCP messages so if this port if this switch detects it coming on this port you've configured this port here as interested and you know which ports you trust because you're the network administrator this port so it comes in and that is permitted through untrusted it comes in and blocked and then you would normally get notified as the administrator that hang on something's not quite right here with a text phone call or other type of alert uh vlans these separate your host into function so here you've got the sales team you're accounting uh Team the IT team and then your human resources and what this does and it depends on the design methodology you're following by the way there's a whole bunch of ways to design your network depending on which vendor you're speaking to but we've separated ours into functions now if there's a broadcast say there's a a fault on the network card for this device here then um the broadcast traffic because each VLAN has its own network address so say that's in 10.10 uh 10.20 10.30 and uh 10.40 so these are all different um subnets and in order for these to communicate you'd either have to have a layer 3 module in this switch or the switch would be connected to a router as we've spoke about earlier if there's a broadcast through this faulty network card here it's basically restricted to all devices on this VLAN and then what would happen is the the your phone would go somebody would call tech support and um it would help you in your troubleshooting because the broadcast isn't affecting everyone here but basically you're told that um everyone in the sales team is getting a really slow Network response and then this this um this is known as the divide and conquer method of troubleshooting you know that everyone here is affected and then so you'd be looking at these ports on the switch you could use a the sniffer the network sniffer and you'd probably quite quickly see the IP address dot one is sending out normal about traffic and then it's gone through the roof whereas all the other devices on this particular and segment of sending a normal amount of traffic access lists and these can be used to block an entire network or subnet one particular host or a number of hosts a particular port number or a protocol so um icmp or um whatever you want airport numbers could be anything dhep DNS host dot one and then obviously entire Networks so it's a list of permitted or denied traffic so if you don't worry about the uh text here because you're not expected to know this for the exam you've give you've created an access list and you've said do you know this traffic icmp and permits IP traffic and what happens is the access list always processed top to bottom I've only got two two entries on this so it'll be pretty quick actually but as soon as the access to this reach is aligned so say it's icmp traffic it would reach this particular line and then it would be a match and it would be denied the access this wouldn't go all the way to the bottom if it's not icmp traffic it would reach the next item on your list and the chances are it's going to be some other sort of Ip traffic and it would be permitted honey pot honey net honey pots attract possible attackers into an isolated environment so this is your attacker and it's a potential victim and what they don't know or they should know is they've actually been fooled into redirecting into this um new net system they can't do any harm in this place and what you can do is this is a pair of binoculars I know it's absolutely Dreadful isn't it this is you as the network administrator watching what they do you'll obviously be doing it via whatever software and you can see what commands are executing and trying to inject pieces of code and this whole environment here is um protected is segmented off from your network and then that that lets you design a series of steps to protect your network so you're analyzing the behavior and Gathering the information if it's a honey net it's basically a chain of Honey pots so you've got you've got your honey pot here and but what you've done is you've chained them together for whatever reason I usually place in um Network segments this will this will be isolated by your firewall so they're coming in and they get redirected to your firewall this is actually your local area network over here sting uh comment here have actually got the um the pen test certification out I'm looking into adding it now um so keep your eyes open it scans your network in order to find ports or protocols with floors I've talked about this kind of stuff before part of your regular security ordering and audition process so say every every Monday you carry out this particular um test on your network it can simulate a type of attack and um it's well recommended that you you do this so we've covered a lot of stuff here um managing your signatures device hardening changing your native VLAN must do protecting your ports we looked at um protecting it from the STP packets coming in the bridge protocol data units so we don't it doesn't become a root or um and it doesn't change the um it doesn't become a report and it doesn't become the STP um root either both very bad things for your network access lists Honeypot and honey Nets and then penetration testing so that's all for now thanks for watching [Music] welcome to module 14 lesson three policies and best practices a few things we want to cover here the privileged user agreement your password policy on off-boarding which is when people join your business and leave whatever reason your licensing restrictions restrictions International export controls preventing data loss and remote access policies incident response policies bring your own device acceptable use policy your non-disclosure agreement uh system life cycle and safety so your privileged user the privileged users are people you could call them super users or administrators whatever this um agreement should be signed by administrators so the Crux of it is that they should only be using the networking tools for job purposes I know where I where I worked at this um ISP we all worked in the um the admin team we were doing the network support for large customers and then obviously there was a whole bunch of teams under us here like a HR Finance Etc but none of these could get out to their social media this is say for example Facebook that was blocked but the admin team they could obviously decide what went in and out of the network so they let themselves get out on Facebook eBay whatever they wanted so um we didn't actually have a user agreement there we just got hired and we started working but really the point of a user agreement is you're not doing things for the network or giving people access to things that aren't really work related so access only areas that are under your purview so as the administrator you may or may not be able to configure ways of you getting into firewalls and other devices that you might not manage but the agreement that you've signed should prevent you from doing that user accounts only changed under company policy and with correct authorization so this would be something like a friend of yours that's asked to to get out on some device or they're asking if they can and access their emails from their home computer these things that you might be asked to do but you you shouldn't be allowed to do your password policy uh I've actually seen a few um News interviews especially in the last couple of years of people giving interviews when they're at work and you can actually see a Post-It note on their monitor yeah saying what their password is so this is obviously a big No-No some of the things that you maybe maybe implemented are they're no reuse or changing the last character such as a if your password is a b c d e f g one you wouldn't be allowed to change it to all be the same and then two on the end obviously for the work Network no writing on Post-it notes expiry length again this is all a pain because people are going to be forgetting their passwords and logging tickets it just depends how secure your environment is upper lower case is pretty common plus special characters and numbers non-dictionary words so again you could be just looking at and people choose things they're going to remember like um I think there's only one Ellen Bloom but you know what I mean balloon kite teacup all these kind of things are they allowed to use passive password management software I've got password management because I've got maybe 150 different types of software and service I use I've managed about I've got about 14 15 websites some I'm on every day and some I only check in once a year maybe but I mean just to try to imagine you can't have the same password for all of these or you shouldn't so try to manage them this is a bit too difficult it's a robo form I think it's called on off-boarding so policy for hiring people and then terminating this should obviously go through the HR team as well because the chances are if it's a big company you may not know who's coming who's gone and and obviously sometimes people will give notice and they're for um privacy or whatever other reasons uh they're not allowed to work at the company anymore they're basically in in the UK it's called gardening leave they're told to leave immediately but they're paid for the rest of their contract what access and privilege levels they're given and when are they given email access and access to Shared directories and files are they given best practice training this is normally um in the form of CBT and then they get a certificate maybe and then that goes off to the manager for filing just to prove they've been shown what they should and shouldn't do do they get a smartphone another what are they allowed to use this Smartphone for uh licensing use of corporate hardware and software and I remember when I worked at a large company I won't say uh who they had um they had a few servers that we could use for internal files but people would download it was cracked software crack software and it was video videos exams and a whole bunch of other stuff that technically should have been paid for with um hard-earned dollars but um it was all put on there for free now the um I'm sure the man at the top managers didn't know but some managers knew what was going on and this is going to leave your your company uh legally a light bulb download and sharing policy training with a sign off which I've already mentioned mentioned could be computer-based training end of training exam I had to do all sorts of things health and safety and harassment all this kind of stuff when I worked even when I was a contractor International export certainly in terms of hardware and software say for example the USA when they developed the um GPS software the it was only allowed a thing within something like 100 meters accuracy the soft the software you they could drop a bomb then within a window of a moving car um but um that was not allowed out to the public and now it's I think it's in in the range of around 10 meters the other thing is obviously encrypted software is uh restricted because depending on the level of encryption issues by uh for terrorist organizations so if you buy any software say for example for from Cisco if it's a high level encryption you'll normally need some sort of license uh you can get it from the government or um you know just to do your own research and see how your government deals with it satellite satellite technology and images that are protected or sensitive uh there could be Financial penalties or you could be criminally liable for uh what goes on so just be careful data loss could be accidental or malicious I've even heard instances of and the talk about this elsewhere but the word computer gets decommissioned sent off for sale in a shop somewhere and then somebody can see all the data I've actually on um eBay I bought a Cisco router I'll do this image here bought a Cisco router I booted it up and I had a load of um IP information password information usernames and this was for a large ISP um an internationally known ISP so heaven knows who was decommissioning their equipment but it wasn't being done very professionally have a policy for your clients devices your network devices and any storage devices and there's normally um software that you can wipe off hard drives or sometimes they have to be destroyed identify what's most sensitive normally addresses credit card information emails make sure people are trained and review the training I've talked about remote access equipment you need to also work out who is allowed remote access this can be um this could be sales if they're on the road it could be um Telly see telecomuters that kind of thing people who work from home what VPN software are they allowed to use are they allowed through SSH software or if they don't have a good internet connection probably people won't use modems anymore but uh disable HTTP access I've talked about this elsewhere https but when you have a device a lot of the time you can put an IP address into a browser and manage it what's your favorite VPN client software what are they allowed to download if anything onto Works laptops are they allowed the intranet what can they see on the internet and where can they access it from Works emails a big one especially with the uh the latest presidential campaign as you know um one of the candidates was accused of download insensitive email onto their from The Works servers onto their home servers what happens when there's an incident there should be a policy because some places have worked people are blaming each other finger pointing nobody knows who's responsible for what so there should be written procedures and also training so everybody knows who's responsible and what the procedure is for um escalating it who gets called who gets paged uh who are the stakeholders so um you know your Chief technology officer your network manager security manager all these kind of people who are they involved depending on what the problem is so identify the start procedures the start the procedures and the steps that take place you're normally work in some sort of framework like ITIL it infrastructure Library they have qualifications on them procedures you should be using who declares it's an incident uh within ITIL you've got um you've got different streams problem you've got the problem manager normally on any team that's one person who everyone reports a problem to instead of basically everyone in the team being told through help desk tickets and then they tell other people the problem manager will receive all of the reports of the problems and then they will escalate it when there's a resolution it'll go through the problem manager and they will communicate it through group email phone calls or whatever uh can their damage be isolated um can it be who's who's in charge of actually removing it who will they speak to can they um who's got the authority to um to escalate it to say um Cisco attack or um the AWS uh Senior Team if you've got a support contract with Amazon uh then eventually hopefully it's recovered Network restored to normal function there'll be a debrief after if you go through the idle procedures there's a normally a meeting a resolution and then something will happen to um change the procedures so it doesn't happen again the training or there could be some sort of consequence if somebody's made a mistake that they should have known better BYOD bring your own device normally and not allowed in fact most places really should have the USB ports disabled um and decided who can use what where the policy per device so for example um can they bring a whap in probably not could they bring a USB device in even phones are they allowed to bring phones in could they try and pig you back onto the wireless network all these kind of things there should be a policy for and who owns what data if somebody brings in their device and but they're using it for work you know who entered data this all needs to be clear what applications can they use and what can be taken off-site as well you need to decide what hardware and software can be taken off site the acceptable use policy uh stop and search depends where you are and how secure the site is but people can search your bag uh speaking of which I already mentioned the acceptable use policy there should be a security policy included how the network should and shouldn't be used what you're allowed to do it should be clearly spelled out and signed websites you can access I know when I worked at this particular ISP at the end of every month the manager would per employee they would have a list of every single website you went to and how many minutes you spent on the website so if you've spent 60 Minutes on whatever say eBay even though and we couldn't do it but say you were found to be on eBay for 60 minutes then obviously there's going to be a consequence you'd either be told off written or an invariable warning or you could be sacked and what you can and can't download a social media again this is a killer you're not really being paid at work to social media unless it's part of your job for example digital marketing NDA as well these are these are huge in the corporate environment protects non-public information so you're you're learning about customers names phone phone details uh who are the key contacts all of this kind of information what are the consequences of the breach this could be um Criminal or it could be civil so you could have to pay Financial penalties and this creates a confidential relationship between the disclosing party and the receiving party your boss or your company and you which is fair uh the system life cycle which is asset disposal something is brought into um Commission oh sorry I did this in a weird way so integrate devices some something is brought into the network and then it would have to go through a chain of events for example a router would all have to be cabled up then it'd be passed on to another team to do um username and passwords for example then it might go to the security team for configuration then it might go to the backup team to make sure that it could and they can download files and configurations and recover it if there's a problem and procedure to decommission what happens uh does it go in the bin does it go to a shop for sale and as I've already said and if it's going to go for sale then all the date all the data needs to be removed hard drives are they going to be scrubbed are they going to be physically destroyed in a furnace or some other device what are the laws for recycling a lot of countries now are really hot on and non-recyclable stuff so if you can't destroy it how are you going to render it and usable or the data on it unusable certainly safety procedures um so who can troubleshoot the equipment people need to know what air their job is you could um ignore that sorry authorized Personnel who can cable stuff who's been trained who's insured monitors as well certainly the old cathode ray monitors there was the back of them and the front uh just massive things it would take two people to carry them and they'd have a massive electricity electrical current going in through them as well even when unplugged um it still held a massive uh current and could have shocked somebody or killed them who can move what uh heavy lifting so I work for as I said an ISP and I work for the network support team I remotely accessed routers and switches firewalls load balances and one day uh one of the one of my bosses asked you know you've got racks these big racks that are full of really heavy equipment and some of it can take up a half rack a massive Cisco switch and he came and asked me if I could remove one of the switches and put a new one in now I wasn't actually there for that this is down to the hardware team at the time this stuff weighed something likes um say 150 kilos and he was asking me to somehow pull it out put it somewhere and um put the new one in I wasn't actually trained to install this heavy equipment I I didn't have any safety equipment I couldn't move it and um maybe he just didn't care or he was just ignorant but I had to turn around and say well I'm not actually qualified to move this equipment but I am qualified to support it but I can only connect to it over the network um he wasn't very happy but it's better than me breaking my leg or whatever is there any safety equipment required normally when you're installing heavy stuff you need a hard hat so you you need your hat you need your boots uh you've you've got to have read the training manuals um are you insured and there's a whole bunch of stuff yeah normally it would go in a trolley again who's who can use this trolley uh electrical circuits certainly in many countries for example Germany and Australia you can't even change a plug you have to be a qualified electrician to access electronic equipment all right so we've covered a lot of stuff your user agreement your password policy and the levels of password leaving the company so joining leaving the company any licensing uh export for example security images and um all this kind of stuff what's it protected by and what you can explore and import what happens to prevent data loss of remote access what happens was that when there's an incident can you bring your own device hopefully not sign in the acceptable use policy your non-disclosure system life cycle and then finally keeping keeping safe that's all for now thanks for listening [Music] thank you welcome to module 14 lesson 4 securing the wireless network a few things we want to cover syllabus items uh WPA WPA2 tkip rc4 ccmp AES EAP lots of abbreviations gfn sync if you've been using wireless routers for any period of time you've probably heard of WEP which was the first protocol used um to secure your wireless network it was um it's pretty much better than nothing I guess but it was flawed very easily crackable and quite quickly after it came out they realized they had to upgrade it and replace it with something better and then it's upgraded uh replace with a Wi-Fi protected access as you can see the title at the top web is a wireless equivalent privacy I think it stands for from 2003 WPA was available it uses as a dynamic key management and it's based on EAP WPA uses temporal key Integrity protocol so I'm glad they do abbreviate it so you've got something like 50 trillion key compilations which is quite a lot you can use it with radius in the Enterprise we've talked about radius and radius servers elsewhere in the course so this basically offloads all of the management and um and authorization onto another device that's um designed for that purpose he uses an encrypted hash each packet has a unique encryption key a WPA2 is based on the 802.11i architecture if you want to prove that documentation it can integrate with ATO 2.1 x there is they do allude to this I think in these syllabus actually and it's a method of authentication and authorization running on their layer 2 networks it's covered in quite some detail in the Cisco CCNA actually this allows users and devices to authenticate with EAP plus it uses tacaxa radius so just take a little bit of setting up but you'll certainly find this in Enterprise level Networks the rc4 was replaced by Advanced encryption standard AES this is 256 bits as a minimum and Beyond a TK IP was replaced by computer mode with Cipher block chaining ccmp uh and I've already mentioned uses uh encrypted hash each packet has a unique encryption key um again I mentioned this earlier MAC address filtering I've just found a basic uh router here and even this cheap one and looks like um maybe it Linksys one at the looking at the colors you can use their filtering enable prevents clients um listed from accessing the network if you want to stop certain clients or you can have a permit only list whereas you manually and decide which packets go and which Mac addresses are allowed uh should be used with other security features in case of Max spoofing and it's quite easy certainly on devices I've managed to log in and manually change the MAC address of your device and here's a permit list for just a random device a random device I found EAP extensible Authentication Protocol it's a framework used in wireless networks they've got an RFC for it if you have the time to look 100 plus types available so I think they're only list three or four in the syllabus EAP md5 uses a series of challenges and responses TLS this was designed by Microsoft and uses a certificate system fast is a designed by Cisco and it uses a TLS tunnel with a secure socket layers and on that node it also uses shared secret Keys these are unique to each user and they have protected access credentials ttls uses the secure TLS tunnel and then finally this is also in a new one in the syllabus uh PE AP increases the protection of authentications by creating a protected TLS tunnel and within the tunnel on Authentication Protocol such as Ms chat version 2 can then be used geofencing is a feature that is actually built inside software so you don't actually have it running on its own it uses GPS or radio to Define geographical boundaries I.E who's allowed in and out of your network or device uh triggers this default the triggers defined for devices entering or exiting the network boundaries all right so just some of the we're basically hitting some of the syllabus items so this is why we went through pretty quick uh WPA tkip ccmp EAP and GF and Tim okay that's all for now thanks for watching [Music] Network Tools hardware troubleshooting tools in all the previous lessons we've talked about a lot of different things and in the very previous lesson we talked about network security and how important it is so in this final lesson I want to talk briefly about some of the network tools that were going to be useful when we're running a network specifically in this module about some of the troubleshooting tools we're going to start off by discussing the general top topic of Hardware diagnosis and troubleshooting and then we're going to move on to talk about four common tools that are used in troubleshooting software these are the diagnostic disk multimeter cable testers and a postcard there are of course other tools however these are some of the major ones that we want to know specifically for this network plus exam if you recall very early we talked about some of the cable tools as well such as toner probes and punch down tools and those sort of fall into here but those are more tools that we use to create cables rather than ones that we're going to do troubleshooting with so we've briefly discussed Hardware in the past but we need to take a closer look at it for the sake of this module Hardware is a term that refers to the physical components of a computer system including hard drives power supplies RAM and other stuff Hardware unlike software it's not a program it can't be installed it can however be physically placed or installed or changed in some cases but this generally requires taking apart the unit and physically installing something new on it and when we're talking about a computer I just want to point out that a router a switch these are types of computers a printer they do have Hardware inside of them so important that we realize this term is really all-encompassing and because Hardware is made up of physical components it generally takes physical tools to troubleshoot them by saying physical tools this means tools that physically come into contact with the hardware in order to test it now some of the hardware troubleshooting tools can actually be programs that run on the computer and one of those I'm going to talk about in this module so this non-physical troubleshooting tool is commonly called a diagnostic or diagnosis disk this is common software that's used to test the system's Hardware or in some cases the router's hardware and so on it runs a series of tests on different pieces of the hardware in the system and if there are issues that need to be fixed it'll notify you you might be thinking if the hardware of the computer is meant malfunctioning how can you run a disk well as long as the system's clock circuits disk drive and CPU are functioning diagnostic disk can be used so again it does require CPU the disk drive or the USB contact whatever it is that is going to contain the disk or we should say perhaps disk in some cases and clock circuits which are the circuits that allow the CPU to run now I just made the C right here because a disk with a K it's like a hard disk like USB drives flash drives a disk with a C is Optical now in general these disks aren't going to State what the problem is they're just going to say that there is something malfunctioning and then it's your job to actually take that information and relate it into something useful they usually do this by producing a list of all the different Hardware components and basically saying which of them is malfunctioning the course of action is then up to whomever is going to physically make repairs or test for more this person is usually the administrator or an I.T consultant or specifically someone who's been sent out by the manufacturer there are a number of tools that they can use to diagnose once they know what part is malfunctioning a multimeter is one of the most common tools that we see in the field of electrical work and hardware troubleshooting it's used to test circuits outlets and other electrical components of most devices now there are very different types of multimeters out there but they all generally test for the same thing they measure electrical current resistance and wattage or voltage rather current is generally going to be measured in watts resistance in ohms and voltage in volts in the case of a hardware troubleshooting the voltage and resistance functions are actually going to matter the most may tell us information about say the power supply or the wall socket that's plugging into now the only times that you're really going to see or use a Multimeter to be helpful for troubleshooting is when we're talking about power supplies and fuses which are also related anything that has to do directly with the electrical on the OSI model what we're looking at here is layer one the physical layer voltage tests are important because they can see if the power supply of a computer or device is actually receiving power the multimeter shows there's no voltage and the power supply is probably malfunctioning the resistance function is used to test fuses if the fuse is blown or faulty needs to be replaced the multimeter is going to tell us this by the resistance so this is sort of what a multimeter looks like this one would be considered analog because you can see right here it has a basically a doesn't have a digital output it's going to measure it with this um arm here that will move and then you can read it based on the numbers that are above there are as well digital multimeters but either way they're all going to have two probes which are generally black and red the black road probe rather is usually either for the ground or the negative and the red just like on your car is going to be for positive the dial in the middle is going to be to test to determine what you're going to test for are you going to test your voltage are you going to test for ohms are you going to test for wattage etc etc by the way the reason it's called a multimeter is because it has a volt meter in it it has a ohm meter in it Etc so we combine all of these into one device which is called a multimeter this probably looks familiar if you have already taken the a plus exam now out of all the hardware failures that can happen the one that's most common has the biggest effect on the network is cable failure this type of thing happens all the time and there are tools that are created to help with this problem cable testers are generally hand held devices that are meant to test cable connectivity they test to make sure that the data is being communicated through these cables properly and there are a few main types of cable testers continuity testers are the least expensive kind and all they do is test for a broken cable basically they tell you if there is continuity in the line data cabling testers are a bit more expensive they can actually test broken cables and properly Twisted cables shorted connections and more they'll tell you what pins within the cable are faulty finally there are things called time domain reflectors or tdrs they're the most expensive out of the three so as we move we're going from less to more they test exactly where a break or issue is and the cable can be found so they do this by sending basically out a signal and they wait to see how long that signal if I have a signal let's say we make a little chord here and I have my time domain reflector connected over here it's going to send a signal out and it's going to wait and see how long it takes before it's reflected back then they convert this time into a distance so they know how far along the cable error was found this way they can literally tell us where the problem took place and help us fix the problem at its source as opposed to us having to sort of try to find this blindly the last thing I want to talk about we talked about this in a plus as well is postcards post stands for power on self-test and you might remember this from the beep that you get at the very beginning when your computer starts up this card is inserted into a slot of a device and it can tell us what is not working in the in the system by giving us generally a sort of code called a postcode sometimes this is a beep code as well generally speaking you have to relate the code to a manual to figure out what it's telling us these cards are really beneficial because they allow us to test a non-starting system without having to start from scratch and restore the entire thing in other words they can test the system that would otherwise have to be restored to a previous version or which we'd have to rebuild so the cards run the tests while the system is attempting to start up and gives us this beep code or this error code then we can go to the code look at a list and determine where the problem is for instance perhaps the ram is bad or is not just not seated properly or perhaps it's not able to find its firmware so just to recap we talked about hardware troubleshooting again Hardware is the hard stuff not software we physically have to deal with it and some of the common tools we looked at were a diagnostic disk which generally is just going to tell us which item is malfunctioning and remember a diagnostic disk is in effect piece of software we also looked at a multimeter which is for electrical things this is going to test volts resistance and current faults and resistance are perhaps the most important ones resistance for fuses or Breakers Volts for power supplies we also looked at cable testers remember there are three different ones that we looked at continuity testers are just going to tell us whether or not the cable works cabling testers otherwise known as data cabling testers will tell us actually which pins aren't working and time domain reflectometers let me write that out will tell us where the error is occurring finally we have our postcard remember post stands for power on self test and this is going to tell us in a non-functioning or non-starting system where the error is it's very much like a diagnostic disc however the diagnostic disc does require the CPU clock and the disk interface is functioning the postcard it's literally a card we insert and it'll tell us itself it does this again by giving us a code that we can then reference on a list [Music] welcome to module 15 lesson 1A physical testing tools just updated the uh from the last presentation really there's a few extra little things slipped into the syllabus which I I think is important to cover the cable crimper the punch down Tool The Wire Strippers otdr cable certifier we may have actually mentioned these in other areas of the presentation but I just wanted to specifically address each one cable crimpa also known as a y crimp hat you'll be familiar with this tool if you've created your own cables a lot of people do at home just to save money because they're so expensive if you buy them from the electronic shops for some reason and also if for any reason something goes wrong with the end of one of your cables you could just snip off the end and just um create your own a cable it's fairly easy to do well with a little bit of practice like anything so you'll need a cable crimpo which you also buy from the electronic shop use to connect the end of a cable to a connector it can depending on which one you buy you can actually strip the cable you separate the wires and then you can um insert into inside here the connector the plastic connector pop the ends of the cable in which you've also stripped With a Stripper and uh and then clamp it closed and that clamps down on the wires in the correct door down different types of cable crimples for different connectors the punch down tool is known as a chrome tool also used to connect wires into punch down blocks it strips off the insulation on The Wire before inserting it into a punch block not something I've used before because I didn't um didn't use any of the punch down blocks uh I did some cabling but didn't use a punch down not something I was interested in wire strippers used to remove electrical insulation from my wire on this particular figure you can see the difference and sizes so you choose the correct size for the cable type and that strips out the um housing of the wire the plastic covering and exposes the actual cable itself it has a center notch otdr this stands for optical time domain reflectometer I'm not saying that again used to locate faults on networking cable I mean there's a argument that you if you just think there's a fault in a cable you just swap it out anyway it'd be cheaper but it's available tool anyway it sends light into the fiber and based on the quality of the reflected light it can determine the following thought location length of the cable loss of signal if applicable a cable certifier it's used to carry out tests it can test the following conductors in the ethernet cable continuity in the wires proper pairing of the wires as well it's quite handy you just plug it in and it will give you lots of different reading depending on the model you have and how much you've spent proper termination of cat cables so they're covered in the syllabus which is why I give them specific slide each instead of just mentioning them in passing as we may have done elsewhere so the cable crimp are the punch down Tool The Wire Strippers otdr cable certifier all right so that's all thanks for watching [Music] thank you welcome to module 15 a lesson 1B software testing tools I'm not going to cover stuff that has already been covered unless there's a new point or some of the reason for doing it uh packet sniffers Wi-Fi analyzer bandwidth speed tester CLI tools command line tools uh not already covered because of the way the syllabus is set out we have to cover some stuff earlier in later and in the middle because it's relevant to that particular subject for example security or troubleshooting I put an image here for Wireshark um Wireshark I'm going to say a must no missed now you must know sniffing and uh Wireshark is just the industry leader and the good news is it's free to download you could have a virtual Network on my Cisco virtual rack which is free on howturnetwork.com it actually you booted up you've got to find your own Cisco image because Cisco don't give them away but I wonder why sharks you can actually see traffic live passing between your routers and other devices this is an essential tool and you need to understand it for troubleshooting so uh really important you can see all your protocols and packets and all that kind of stuff so um you'd you'd normally load this uh software all right the Wireshark it'd be loaded onto your laptop if you're troubleshooting you would leave it running say for example you'd leave it running for an hour and and then you could analyze the output and see where a particular problems happening is it is it happening for the the whole hour is there some sort of um issue spikes and then or does the issue sort of happen over this period of time that kind of thing so the traffic is going into your switch from the server and you will configure um the switch over here you would do a configuration command on the switch to send the traffic out on whichever Port you've connected your laptop to um you've just got to be aware of I'm just telling you this because of the real world you've got to be aware of CPU and you've got to make sure that you get permission off whoever the um person in charge is when I've worked on network teams and um I knew the procedures and policies which we've already talked about what I can and can't do but if it could be Network effect in for example the CPU then you've got to make sure it is done out of hours or you've got permission so you'll check for traffic patterns of Base a traffic Baseline any irregularities they will pop up you'll be mirroring a port just be aware the package slippers can be used for good and bad so they cannot also be used by hackers so whenever possible if you're connecting over the network use a secure shell this is a Wireshark we and they call it captures as well it's handy to know the uh the vernaculars um ethernet zero looks like the port uh you'll you'll this is the dashboard all around here and in this part here you can actually click on these uh little arrows and it will expand so you'll see the layer one which probably won't be of interest to you then layer two and then you can click on this and you will see that it's an ARP packet you will see source uh destination all and all this kind of stuff and then down here is all your ones and zeros and hex which you probably generally won't be interested this looks like it's uh some sort of uh pattern over time and you can see there's a spike here that's more on here and here you can decide exactly what traffic you're you're monitoring this is SS H telnet and whatever you wanted to Monitor and then it's a in a pie chart here and obviously a graph form here really handy so you can go to your customer or your boss uh with all of the facts and say when this happens that happens when this happens such and such Doesn't happen and you can prove what is or isn't the issue on the network so um please do check out the Wireshark certified network analysis um the network associate sorry qualifications really important we've got it on um how to net work.com um I think there's maybe other people offered the course but most people just seem to just Skip by but this this will be a lifesaver if you're looking at being a network engineer anyway Wi-Fi analyzer this is obviously a graphical output that has been discovered with the piece of software it reports on your SSID which you can see here and Mac addresses channels use you can see the Mac addresses of devices here uh challenge use speed that kind of thing and it represents the output in the graphical form as you can see it tells you the security protocols and more importantly lack of so you could um we talked about Rogue access points and bring your own device earlier you could be doing this in work or you could do it as part of a security survey and here's another image from the same sort of piece of software all right bandwidth speed test damage we've all used these because if we've got problems with our speed at home moving at work maybe known as throughput testers they can be Hardware software based it's easier for us obviously to use the piece of software which will send a certain amount of packets upstream and give you a report of x megabits per second then the downstream then the same sort of value so it injects traffic into the network you could actually use this on your Lan one or for your home broadband connection the handy thing is you'll normally get a graph saying um you know how fast or slow it is free to download if you want super duper uh outputs and charts and that kind of stuff it'd normally be paid CLI this is where the rubber meets a road and most Network Engineers kind of worry about using these color commands like even something simple like ipconfig gives you all of this useful information here that help you will help you troubleshoot now you can use the GUI but it's just a little bit more clunky you've got to go through a menu to get to another menu and then it's only going to show you maybe 50 of what you could actually see if you use the um command line and if you're doing some sort of emergency recovery you're probably only got command line available anyway a typical exam question ipconfig will give you the TCP information on Linux devices this ifconfig classic exam question that is IP information for your local interfaces including your wireless adapter any um virtual adapters virtual land cards Wireless or ethernet uh you can use switches to drill down for example ipconfig forward slash all there's a whole bunch of switches actually uh most um command line tools will let you issue the question mark and then it will save these year options IP tables this is a Unix command a lot a lot of people it's you'll either you you use Unix a lot because it's your job or you've probably never touched it at all but it configures the kernel firewall the only reason I mentioned this command is because it's in the the dreaded syllabus oops syllabus so um I think just know this command and what it does known all this stuff I've put it here so you can just see some of the options but I really doubt that you would need to know it um I took this uh lot here from tutorialspoint.com if you're nowhere look at that URL net starts a handy command basically short for Network statistics thankfully so it's easy to work that out shows your active connections tells you the type of services you're running and you could be in for a surprise um if you see things running on your device that you you didn't think should be there there's a few switches let's start minus n minus a minus B I'm not sure you'll need to know the switches although I can't guarantee it active connections the applications the connections without doing a DNS resolution uh here's a net start from uh this is from one of my authors actually I recognize the name from his device he's obviously named his device after himself let's start mine is a and you can see the state of all of these um ports there's an established Port here and then you could obviously do a search and find out what this is he may what may well be connected to a Remote device he may be chatting on MSN or Facebook Messenger or and you could quite easily find out what all these ports are for TCP dump and here's the output here it's a Unix command it's a sniffing tool so what you can do is use it to Snoop um the if you're if you want to do the snooping it's the Snoop command if you're using Solaris um pretty specialized a bit of software but I've seen some of the network teams using Evernote menu you can view the packets on the Y app pathping now this is a tracer command actually it's a TCP tool it provides information about Network latency and sends icmp Echo requests and map I think I mentioned this before actually she used to discover computers and services on a computer network in order to create a map and you can see there's a whole bunch of services here many of them probably look familiar to you and at the end it says Two Hosts up and how long it took to scan it uh vulnerability scanning Tool uh just bear that in mind again typical type of question they'll ask you what's nmap used for or um tick the relevant vulnerability scanning tools used for auditing by you or obviously whatever can be used for good can be used for bad and it can be used by hackers dig and he said the command has been used here domain information growth it basically sends off a query to DNS servers it's the same as the NS lookup tool but this particular one is used for Linux devices now you can see it's done a search for example.com and you can see uh the name servers here IP address DNS servers cash timers that kind of thing that looks like a um that looks like Google actually from if my memory says I think they've got eight eight eight and eight eight four four you can check for yourself all right so looked at some cool stuff uh package sniffer Wi-Fi analyzer bandwidth speed taster and some important command line tools remember we're covering this in in other presentations too so this was just a subset of all the stuff that you need to know so that's the end of the presentation thanks for watching [Music] thank you welcome to module 15 lesson 2 height availability and low balancing we're just hitting another syllabus topic here um just a brief overview really high availability [Music] vrrp hsrp load balancing and high availability this refers to the ability of a user to access the service no surprise High availability is a common networking term it refers to the continuous availability of a service for a higher period than normal now obviously we're looking for the 99.99 percent in order to get the highest possible availability we usually need more than one other thing for example um some Cisco switches come with to power supplies and even even this has been improved upon so they have not just the fact they've got two power supplies but they're hot swappable so what that means is you don't need to reboot the switch you can pull one out the inactive one and then slot another one in and then you've got two active power supply units and in case one fails so measured as a percentage of uptime which is five minutes a year uh for a network to be highly availability it should survive any kind of failure I'm not saying there's such a thing doesn't exist but even the most robust networks there was a recent outage due to um severe flooding in Australia I think it was just a few months ago where it took out Amazon uh S3 service so which you would think would be one of the most available and secure and robust uh hosting Platforms in the world but even some of those customers were taken out so high availability can be achieved by configuring redundant components so if one one part of it fails the other part takes over now in the context of a routing we've got protocols such as vrrp Virtual Router redundancy protocol and hsrp which is done by router protocol these are what are what is known as um High availability protocols these enable multiple multiple routers oral layer 3 switches in fact to act as Virtual Router with a virtual IP address a default gateway is configured with this virtual IP address so one router will be active and this handles all the requests to the default gateway and the other router will be a standby so the other router actually takes over if the main router goes down now this isn't load balancing because um you've got one master router and the other one is a slave or backup depending on the protocol you use they have different terms so here's an image of uh the Cisco hot standby router protocol at the top you with the red and the blue you got a layer 3 switch it should be another there we go so uh we'll see you see the host on the bottom they both have the same default Gateway the Gateway is 10.10.10.1 now 10.10.10.1 is configured as a virtual IP address on the two layer three devices on the top these two devices are connected and they monitor each other so if one goes down the other one takes over you see the priority on the right hand switch is 100 the priority on the left hand switch is 105 so it's got a higher priority so this one in the case of hsrp will be the primary router uh all traffic will go via this router until there's an issue with it if it goes down then all traffic immediately in a split second swaps to the standby router which is on the rides they both run a virtual Mac address we don't need to worry about that because I don't think it'd be asked but they run a virtual Mac address so that um a layer 2 connectivity works also I think that's all we need to know about this diagram load balancing is a distribution of work across two or more resources such as servers and networks if you have a server overloaded with requests then we can have several servers share the burden of that single server in fact even better than that you can um it will it can work so that the load is balanced automatically so you don't have to wait till one server to be overloaded the load is shared over two or more servers now the other thing is just going back to that last point the servers are acting as a single server so devices don't realize that load balancing is taking place the servers are acting as a group of servers with the actual hosts that are contacting their services on these servers for example um surfing a web site and doesn't don't realize then load balancing is taking place so here's an image of load balancing you've got two load balances here so one would be um redundant or possibly taking a part of the load from the other one and then we've got an array of servers providing whichever Services they they may be FTP or web services so load is distributed uh across the servers they'll all have the same IP address and if there's a problem with one of the servers that will be removed from rotation if they're not responding I presume you'll have some sort of reporting software that will send a message to the administrator saying one of the servers has been taken out of rotation so that can be looked into some of the benefits optimization of resources you get faster throughput obviously requires careful planning for all your bandwidth efficiency High availability which is the whole point of the presentation so we've looked at high availability two types of protocols vrrp and hsrp low balancing all right that's all for now thanks for watching [Music] thank you welcome to module 15 lesson 3 we're looking at SNMP syslog and s-i-e-m these are exam objectives you could go into each of these subjects in quite a lot of detail actually there's the entire book so that's an MP which um we won't we'll only be doing an overview so you're familiar with the the terms used we'll talk about these services Harrison MP Works email Cinemas SMS alerting syslogs and the benefits and Siem SNMP you'll be referring to a fair amount as a network engineer a guess I get it just depends on your network some of the larger networks I've worked uh on you actually have a team that deals with any SNMP reporting and any configurations or perhaps as a network engineer you'd have to enable SNMP reporting on a particular device do some testing to make sure that the receiving station the network management station can receive information which we refer to as traps from the device and then you will sign off that device as compatible so SNMP is an application layer protocol and the idea is it Exchange Management data between the devices on the network or from a certain device to the network management station issues to Monitor and manage devices on the network such as router switches servers and it even drills down to individual ports for example if you have a switch with 24 ports the SNMP manager depending on the software you have some of it's free and some of it's quite expensive and it can drill down and show you a pictorial view of each port on the switch including the power and power button and you can enable or disable and monitor and manage individual ports so it's very handy and very powerful SNMP implementation consists of a managed device the SNMP agent little piece of software the SNMP manager which is normally a PC or server that monitors the network and then reporting is done on there pictorially usually the graphical user interface the manage device on the network it requires some kind of monitoring and it can be it would be your servers switches routers firewalls that kind of thing an example is a storage array SNMP agent is a program that runs on the manage device so these need to be written by whoever the vendor is usually so it can comply with the RFC the SNMP collects information from the device and sends it to the SNMP manager the SNMP manager is typically a computer that has the software running for us in mp and a lot of the time it's graphical user interface you'll see different images and diagrams and Reporting pie charts and that kind of thing this communicates with the SNMP agent management information base we call these mibs we don't normally say MIB when we speak to Engineers the maybe is a database maintained by the SNMP agent it contains information about the managed device which is shared by both the SNMP agent and the manager so SNMP is typically enabled when you have a storage system again it depends on your setup whenever whenever a specific event occurs in the storage system this is an MP agent running on it will notify the manager and it sends a message now what happens after that depends on how you've configured it it could trigger a number of events or just be stored so you can see the act I will act now by the SNMP manager what actually happens the Trap is in the is an event that's reported the SNMP manager will receive the event and take action type of actions could be um an email you can configure it to send an SMS to the network engineer or a number of people you can even have um an automatic um phone number dialed or number of numbers dialed voice message is sent it just depends on how you how you configure it and how important this particular message is quote from Wikipedia SNMP agent receives requests on UDP Port 161 it can send requests from any available Source port to port 161. the age of response is generally set back send back to the source port on the manager the manager receives notifications these are known as traps and inform requests there's other types of messages these are on Port 162. so basically UDP ports 161 and 162 is used by SNMP moving on to a syslog which has got quite a lot of prominence in the Cisco CCNA exams it's a protocol for exchanging log messages so syslog generally sits on a syslog server although you can configure it a router to be a syslog server the general rule is leave these devices like a router to do the main job it's designed for instead of um using it to allocate DHCP addresses and record syslog messages although it can do these and a lot more things it can be used by devices on the network to move all the audit logs to a central login server again this is called the syslog server why would you do it it allows the consolidation of audit logs from multiple devices to a single place basically it's for to give you usable information and data you can have different levels of syslog messaging from urgent messages to just general reporting and how and what it actually does is down to you to configure depending on your particular needs on the network okay lastly s-i-e-m security information and event manager it's a set of software products and services that are used to monitor a network what it gives you is a real-time output of security alerts generated by Network and network Hardware so it's definitely got a security bias It's a combination of sem security event manager and Sim security information management the security event management deals with the real-time monitoring and notification of security events the Sim deals with the collection of the log files into a central Repository a lot of the time as with other protocols like this you would have a graphical analysis giving you some sort of meaningful data that you can interpret the Siem Solutions are used to log security data and generate reports a lot of the time for compliance and security compliance is a whole new and expanded area a lot of the time for you to comply with and National standards and requirements for security one example is checkpoint event here which you can Google and look at some more information if you want to do some research but that's um for now summary is SNMP components manage devices and agents and managers mibs we've talked about how SNMP works alerting syslog and why we use this log and Siem okay that's all for now thanks for watching [Music] thank you welcome to module 16 lesson one web services this would obviously uh be a massive area we're just touching on the things that are covered in the syllabus what are web services XML programming languages and web services their components used by web services how are web service works I think uh this has probably been put in in as much as you probably you may be asked to do some sort of troubleshooting not uh in the respective web programming but perhaps accessor through the network or firewalls or some sort of troubleshooting so you may need to communicate with the web programmers at some point what are they there's a whole bunch of applications that use Open Standards such as Excel soap wsdl uddi uses they used to exchange data between the web-based applications over an IP network and this is just a massively expanded area and always has been since HTTP was first used to display web pages it's been improved upon over and over again to deal with them issues speed security usability mobile devices it's just never ending so in a web service we already know the HTTP is used to transfer um machine readable formats such as the following XML Json and Jason when different software Services onto stage dates with each other a web service allows them to do this over the internet software application that requests the data is called a service and you can tweak these way in most of your browsers such as their Google Chrome or Firefox they normally have ways you can manage extensions or um the back end to a grade to a lesser extent software application that serves the data is called a service provider and web services are a means of um interoperating between different software systems the software applications develop using a whole variety of programmer languages and normally you'll have somebody specializes in one or more and you can see a few in the Fig there some have been depreciated such as Flash and due to security issues season for applications want to exchange data they should be able to communicate with each other this may possibly be where you have become involved as the network engineer data exchange shouldn't depend on any particular programming language so there's a need for a common language that allow different software applications to send and receive data over the web most types of software can interpret what's known as XML tags this stands for extensible Market bandwidge which you can learn if you so choose it's a standard language for web-based applications to communicate with one another the exchange of data happens through XML files XML is a markup language it defines a set of rules for encoding documents in a format that we can read as humans generally you need to be a programmer to understand what they mean but it could also be read by the machines so here's an example of an XML file you can see it's marked as XML at the top the version and then there's various um prompts within the greater than and less than markers and also the actual text in between Network 100 status pass subject Hardware Mach 100 so you've seen an example easy to read it once obviously once you've learned what it all means and how it works but it's also easy for the machine to read also allows you to see what's been sent between the web-based applications web services web applications can send data using the XML format they can also retrieve data from an XML file a standard web service uses the following components soap this stands for a simple object access protocol this is actually used to transfer the data uddi stands for Universal description Discovery and integration directory that defines which Software System should be contacted for which type of data wsdl stands for web services description language used for describing the services available how are web service works it uses XML to tag the data soap to transfer the data and then wsdl to describe the availability of a service it's worth writing this out if you haven't already if you're not making notes so you understand which um part performs which service because this is the most likely thing you're going to be asked a question about so we've looked briefly at web services XML programming languages and web services components how web service works that's all for now thanks for listening [Music] welcome to module 16 lesson 2 unified communication just call this UC usually to save a lot of breath as with everything uh different media the same communication we look at and presence this is a real snapshot of a pretty huge subject area so as with a lot of network plus stuff especially the new stuff in the syllabus you just expect it to have an awareness of it you see is the integration of a whole bunch of communication methods including voice video and data all goes into your IP network which is kind of tied in with the cloud now and how everything would be you'd expect everything to be working over IP and over multiple devices depending on where you are and how you want things to work the idea is it simplifies real-time Communications at an Enterprise level including it can work it doesn't have to be Enterprise by the way it can be any small Network including homes making calls instant messages having a video or audio conference sharing your desktop with whoever needs to log in and troubleshoot presence information so you see it's all forms of communications are exchanged over IP integrates real-time Communications with non-real time such as accessing your voicemail if you're not available accessing your email text messages faxes I don't even know who uses those now it allows you to send messages on one medium but receive a response to another an example is when you send somebody a voicemail you've probably had this happen before or you've left a voicemail and it says it will send the user a text or email you can retrieve um check and retrieve emails or voicemails using any Communications at any time our presence is a component of UC shows the present status of a user in real time whether they are available and available where they are located if if you've enabled geoip tracking or Geo tracking sorry allows users to communicate seamlessly even if they're in different locations you can look at a person by accessing an interactive directory and engaging communication through text voice or video so that's the summary of what we've covered just wanted to go and show you just for more context really Cisco's unified Communications I'm just going to play a video this video is copyright Cisco system so if you want to learn more um all you do is go to Cisco or in fact type Cisco unified Communications I'll just put a video on now foreign [Music] thank you welcome to module 17 lesson one introduction to virtualization this is one of the few new topics that have been added to the syllabus surrounding virtualization and cloud computing and come to your offer a cloud certification actually there's a cloud Essentials and I think there might be a cloud Plus definitely a cloud Essentials because we host uh host that course all right module objective is the definition of virtualization what is a virtual machine and the software I'm sure you've heard of it actually it's the new or one of the very new and exciting emerging Technologies that's made alive a lot easier for Network engineers um companies from a financial and operations standpoint and also home users who can do a lot more interesting things on their um systems at home so it refers to the technologies that allow a single physical computer or or server obviously environment to operate as multiple virtual machines simultaneously transforms the physical Hardware resources into virtual Hardware resources so what you normally have one device running one operating system you can have depending on how much Hardware you have and how you apportion it and two or more virtual machines a virtual machine is an isolated software replica of the original computer so for all intents and purposes it appears as a machine in its own right with all processor instructions and system resources so you'll often see an image like this where you have a physical computer or server and inside and it will represent a number of virtual machines much in the same way as their vlans they operate in their own right as if they're an actual machine a virtual machines are completely separate and independent by running good operating system in each one it becomes possible to run several guest operating systems at the same time so you could have um a Microsoft Linux and other operating systems running on the same physical device but different virtual devices a whole bunch of virtualization software around some free some um you have to pay for and you get different levels of um software up to Enterprise and obviously support contracts the software transforms the hardware of the computer including the CPU memory Network adapting to Virtual resources these are shared amongst virtual machines it basically provides a layer of layer of abstraction so for all intents and purposes there's a divide a virtual divide between all of these different machines the labor of abstraction is basically there to hide what's happening underneath what you can see foreign as a result the abstraction provided by the software the guest operating systems are not tied to the underlying physical Hardware so this is how we can actually get it all to run so you have a portability of moving virtual machines from one physical computer to another physical computer if you so wish great if you want to do testing interoperability stress testing or just practicing even if you want to do some install various operating systems onto one device in order to practice free exams or job interviews so this is just an overview we've got more to cover in the following presentations what is virtualization the virtual machine the software that's all for now thanks for watching [Music] welcome to module 17 lesson 2 virtualization components and software-defined networking or sdn for short looking at virtual networking virtual network adapters a virtual switch Virtual Router Virtual Router via vrrp the virtual firewall and sdn and while we why would want to use sdn so a virtual network is a system in which the following is true you've got two or more virtual machines connected logically to one another they could each just send received data as if they were operating as physical devices I've got an example here esxi which is software available from VMware I think they do offer some free software I haven't checked as to which um is free for home use or commercial use and I recommend you check out the VMware certifications on howturnetwork.com they're very relevant for modern day networking so they can send to receive data from each other the virtual network adapter is a software implementation of a physical network adapter which I'm sure comes as no surprise so you have a physical adapter but the virtual one is acting in exactly the same mother and same manner sorry and you've got a diagram here of a physical network card um and then you're working as a subset of this is your virtual machine they're running virtual network cards and virtual machines on top of that the virtual network card interface is a virtual machine to the network they can have one or more virtual Nic next or v-nix eat such Phoenix has its own Mac address it needs to follow the same rules as physical networking so it'll need to have a unique Mac a virtual network card in a um virtual machine you still have to configure it all the same rules apply it's just the fact that it isn't operating uh physically so you can go and see and physically plug and unplug cables virtual switch or v-switch is a software version of a physical switch it's got Network ports similar to the RJ45 connectors you have and one 1016 virtual ports this all depends on your software and Hardware platform you're putting it on there's a limit of 4088 ports on all virtual switches on the VMware esxi host different vendors May well have different um capabilities and rules to follow a virtual send switch can send Network traffic between virtual machines on the same host or from virtual machines to an external network that's outside the virtual virtualized hosts you can go to YouTube and check on videos on how to check a virtual air device to a live Network and a lot of the time you do it for home use to overcome um limitations when you're trying to get different bits of software and Hardware to work for certification exams it's quite common virtual switch joins the network with a physical Network when it when it connects to a physical switch using um physical network adapters uh you can also get virtual routers a software version of a physical router obviously performs your layer 3 packet forward in between your subnets or lands and um vlans obviously you need layer three capability of some sort a virtual router via vrrp which we covered that protocol earlier uh it's a virtual route is implemented when you use vrp to provide redundancy of the default gateway so all the hosts still have IP connectivity it's back by two or more physical routers depending on the protocol you can have two or three I'm not sure what the limit is actually depends on the protocol and it does change uh why use a Virtual Router provides the same routing function functionality but it's virtual so you've got all the advantages of costs uh virtual firewalls they're mentioned again in the Cisco syllabus probably definitely the CCNA routing briefly but I would imagine in the CCNA Security in a lot more detail so it's a virtual version of an actual firewall so they're implemented as a follower within a virtual machine or as an appliance it provides security to your virtual environment does exactly the same job as a hardware firewall just moving on to sdn now it's um a big topic and it's been introduced into the new Cisco CCNA exam and I would imagine um it's going to have more and more prominence over the years to come because Cisco have invested heavily in sdn and there's a lot of um some Open Standards that have had a huge uptake as well it provides um a high level Administration capability to network admins it allows you to manage your entire network through a user interface that abstracts a com complexity so you wouldn't necessarily need to understand all the underlying commands that have been executed and how it all works um just to manage it if you're using sdn obviously it helps if you to be a network engineer that you actually understand what's happening but um now I suppose it's like managing your car they've got all these different settings on the onboard computers that change your handling and your engine performance and all that kind of thing you can turn different controls on or off like traction control and you don't necessarily need to worry about how it all works all right sdns are used to control the operation and network devices um look into more I think Cisco I'm not sure which CCNA version maybe data center that looks interesting any more details but there's a whole bunch of um controls and formats that have to manage your um interface between your network the user and all of your devices and apis to name one so examples of sdns or Cisco open network environments nikira's Network virtualization platform why bother it basically makes your life a lot easier as the network administrator you can interact with your entire network without having to actually connect via telnet or physically connect to your devices or even understand all of the different commands so if you're using Juniper Hardware it's got one type of um command line interface for um copyright reasons your Huawei and Cisco all got different command lines different commands all to achieve the same thing so you don't you don't need to worry about that if you're using SDM so get get rid of the command line some of the benefits again the graphical user interface provides information about what's going on with your network it allows you to specify changes and behind the scenes the actual configurations are done with the interface one of the apis between the software and the hardware all right so it's just an overview looked at virtual networking the virtual adapters virtual switches and routers the RRP firewalls and software-defined networking and why why would we be interested in using it so that's all thanks for watching [Music] welcome to module 17 lesson 3 the storage area network I think come to your actually have a qualification uh storage area networking engineer Plus and we actually have um such a course on howturnetwork.com this is just an overview touching on some of the subjects they mentioned in the exam syllabus looking at storage area networks direct attached storage network attached storage sanvi Das Sun media fiber channel iSCSI San Jose architecture and components of voice guzzy also jumbo frames Sun as we already know stands for storage area network it's a high speed Network the idea is it allows um transfer between the computer systems and the storage devices it's optimized for this type of Technology as well we'll see this as we go along and here's an example which will um you'll see in a few slides so why bother at all why do we need a storage area network again everything covered really in the network plus was created in order to solve some specific or general networking problem it's the evolution in data storage technology and we'll look at some Legacy ideas in a moment so um unfortunately this I'll put the wrong order here so the lines are appearing in the wrong order there's been progress in the data storage technology from Das to Sam direct attached storage is the traditional way and it's I'm sure many companies still use it those who don't use uh San as a solution for storage so a traditional client server systems each sort of server having its own storage and the storage is directly attached to the server internally usually or it could be external search a technology is referred to as direct attached storage or Das so there obviously has to be advantages it's high speed and it's exclusive access to the storage so it's not shared preferred by small companies just cheaper to implement easier to implement easier to um troubleshoot maintain obviously there are disadvantages which is why it's been um superseded by many companies so what you get is a pocket of isolated storage it's not officially utilized and this ties into virtualization really where you we've got this whole amount of resources but we may only be using a certain percentage of it which is a waste so for example when one server has plenty of C uh free storage and the other one has almost ran out of space then we've got a disparity this is where um Network attaches storage will help direct attached storage design doesn't allow the free capacity of the servers to be shared so when a business deploys more servers in the network the following occurs there's an increase in the wastage increase in the complexity of managing all of these isolated storage because usually you've got raid so you've got to insert and pull out various disks and network attached storage another image there it decouples the storage from the servers so the servers are still there but we um remove the storage as another feature makes the storage a centralized pool of shed devices that can be accessed by all the servers connected to the network now network attached storage is not a network in its own right but a storage array hooked up to an existing Network here's an example of a Nas server that's a Netgear by looks of it it can provide centralized um shared stories of terabytes of storage you get enough servers for home users as well wherever everyone can connect to this particular device and hopefully that device then in turn backs up somewhere over to the cloud or somewhere like that disadvantage is doesn't provide the high speed data protection needed in Enterprise environments because it typically sits on an existing shed corporate Network um complete data backup takes a lot of time and obviously takes up a lot of bandwidth so sun is a dedicated Network that transfers blocks of data at a high speed to a storage device a low latency for the input output request to the storage device uh what you what sound gives you is access to several servers that connect to several several storage devices you can see we've got a in this instance we've got a full mesh connection between the servers the switches and the storage array there also allows the storage devices to communicate with each other limitations going back to direct access storage this is the challenge we have with the traditional server attached storage you can't satisfy the ever crease in demands for storage and we obviously have more and more complex information including video and voice not scalable due to the restrictions and how many devices you can add physically to um servers sun is scalable so you can add a lot of new devices and and without having to add new servers you can aggregate the devices into a central pool that can be accessed by the servers the server attached storage doesn't provide High availability because if a server goes down then you lose the data since the data is tied to the server so obviously um overcomes this problem because you remove the storage from the servers if a server goes down in the topology then the data is still accessible so you've removed that as a point of failure and though the sun connects multitude of servers and storage devices the performance doesn't so far because the network is characterized by high speed and low latency you've got the best of two different worlds there the high speed data transfer the low latency can be compared to the high performance of storage directly attached to a server so your storage area network is a dedicated Network it's scalable and highly available as we've already said primary purpose is providing the high speed and the low latency Sun media it's the actual cables and physical wiring It's associated with the unique protocol and is always managed by that protocol the protocol is responsible for the format and sequence of data exchange on the storage area network now you're almost always going to have um fiber channel and because of the speed requirements different types of optical electrical transmission meter that you cannot follow that and you can have copper the fibers of preferred connection type uh the sounds are typically typically built using fiber channel uh the standards you define a high-speed Network that transfer dates at around two gigs per second the standards also define the properties of the media and how data is transmitted which I mentioned earlier fiber channel is a de facto standard the storage area network using is built using fiber channel technology is called the fiber channel or FC San uh the whole idea is to increase access to all the data and since organizations have a heterogeneous combination of operating systems fiber channel was um designed to cater for all of these different applications and operating systems the fiber channels solve the fundamental problem of reliably making terabytes of information available to hundreds of servers more than likely at the same time as well so serving multiple requests uh while direct attached storage and network attached storage may be appropriate for small networks the fiber channel San is used generally for large storage networks and Enterprise Networks um con the concept of sand isn't tied to any particular technology or vendor so it can be used by a multitude it can also be built using other Technologies such um as Internet Security or iSCSI is a storage area network implemented over an IP and it uses the iSCSI protocol it's a mapping of the scuzzy protocol over TCP not sure if there's an RFC for this actually but you can Google the ice cozy for yourself and see um where the proposal started carries Block Level data over the IP network and block storage can be accessed over the network as if it was directly attached to the server is because the architecture is based on the client server model of scuzzy it's because the parlance is referred to as the initiator target model which may be you may expect a question on something along those lines for the exam the iscosity sign consists of three components initiator the Target and the IP network the initiators the system that first initiates a read or write request over the IP network example of a device is the server Target system is the system that responds to the requests so an example is the storage array initiates initiators and targets need the physical is because the interface to connect to the IP network the Isis interface is available as a PCI expansion card or it can actually be built into the motherboard again you need to speak to the vendor and look at your particular specifications and requirements jumbo frames you may heard of before in network parlance it's an Ethernet frame it's got a payload greater than 1500 bytes and it can carry a payload payload of up to 9000 bytes so on the contrary an Ethernet standard frame a standard ethernet frame sorry can carry a payload of 1500 bytes the payload or the size of the largest data that an Ethernet frame can carry is referred to as the MTU and if you ever use a package sniffer you'll see you should see for ethernet and MTU field the maximum transmission unit since jumbo frames have larger mtus they can carry more data each transmitted frame and a network requires a network hardware and software to process it so we have the more frames we have the more CPU Cycles are required to process them so if we use jumbo frames it only requires a few we require less frames because of the bigger MTU size as a result we get less CPU utilization but we get the bonus of increased throughput uh we can use jumbo frames when fiber channel frames are to be transmitted over the ethernet the size of the fiber channel frames are over 2K so it becomes necessary through the adapters and switches to support baby jumbo frames in order to prevent the segmentation I think we covered segmentation early it's when the frame is chopped up into different pieces numbered and then transmitted and each frame has to um has to have an acknowledgments so you've got a lot of overhead associated all right so we've looked in brief at storage area networks direct attached storage Nas uh Sun versus Das Sun media fiber channel and iscs architecture and Sam the components of Isco Z and jumbo frames thanks for watching [Music] welcome to module 17 lesson 4 Cloud Concepts I've mentioned earlier well worth doing the CompTIA Cloud Essentials exam because uh cloud computing is just one of the core subjects that you need to understand as a network engineer among us a few others including routing virtualization um probably Amazon storage uh routing and switching for example the CCNA IPv6 so this is just a real uh brief taster looking at cloud computing characteristics on-demand self-service broad network access resource pooling elasticity measured service software as a service platform as a service infrastructure as a service and then private community and public clouds on hybrid clouds so best thing is to start with the definition so we can kind of have an agreed kicking off point of what cloud computing actually is now cloud computing from the definition is a model for enabling ubiquitous convenient on-demand network access to a shared pool of configurable computing resources examples are network servers storage application and services that can be rapidly provisioned and released with minimal management effort or service provider interaction we've all used the cloud already if you've used any storage for example Dropbox box.com I think the call for storage any Google services for example Gmail or Google documents and things like that there's many many others and are all based on the cloud so some characteristics that you need to remember these so make sure you note them down there's five characteristics of cloud computing on demand self-service broader network access we'll go into all of these in more detail resource pooling rapid elastis elasticity a measured service so on demand basically means the user can provision resources as and when they're needed without getting any human assistance so you if you needed more memory you wouldn't have to log a ticket and you wouldn't have to have an engineer somewhere turn off the server or whatever the device is adds more physical memory reboot it and then answer the ticket as you may well have had to do in the not too distance past you click a button and more is available we can do when consumers provision the resources based on their needs those resources are automatically allocated from a shared pool and their schedules provided by the cloud service provider broad network access means that when the consumers have provisioned the resources they can access these from a number of devices workstations laptops tablets and mobile devices and mobile phones resource pooling and the service providers resources are shared and when the consumers on a multi-tenant Model where consumers get a dynamic allocation resources based upon their needs so sometimes consumers may need more Computer Resources and other times they need need less so it has to adapt for this particular requirement it's um resource allocation based upon demand rapid elasticity I can't say that word elasticity foreign now a consumer can be allocated more res me more more resources if needed at the same time if for any reason they need less because the more you the more you need the more you pay obviously if you need less then they can be downsized to provide whatever model you need the resources you need so it appears to the consumer that there there's an actual unlimited amount of resources for them at any given time elasticity provides a lot of savings because it's not possible when you have a traditional data center that you've built and you own you can't grow it and shrink it as and when needed obviously is measured just like a meter so you're charged based upon your um a number of things such as um memory you need uh storage and uh bandwidth so you get what you pay for which you've already said is um uh tracked normally you can log in and you can track your use of resources in real time as well as historical data looking at um how much you've used and the projected requirements based on previous usage and you can see how much you're going to have to pay how much you paid in the past there's three service models you need to be familiar with software as a service platform as a service infrastructure as a service providers provide the services to Consumers based on these three service models so SAS swas or SAS consumers can use the service provider software applications and databases over a network without the need to install any software except for a web browser you need to access these uh software applications databases run on the cloud so imagine you're trying to program um some application for example or just use a huge amount of resources or develop a program you can use the provider's resources and scale it as and when needed it's provided as a shared Computing resource to the consumers it's essentially the aggregation of hardware and software used to support the cloud services a few examples you can see there are Twitter and Facebook there's a whole bunch of others you can look into if you wish though in the SAS model consumers access the shared applications over a network from various client devices it doesn't give you the ability to control and manage in the manage the underlying Cloud infrastructure so you can't manage the operating system servers the network or storage and you don't you don't want to anywhere you just want to um use it as is platform as a service there's an example there Windows Azure which you could look into in your own time in the platform as a service model consumers have the ability to develop and deploy software applications on the service providers Cloud infrastructure uh the service provider typically provides a competing platform comprised of the operating system and the application development environment this includes programming languages libraries tools databases and web servers I recommend you look at the Amazon AWS qualifications for more information on these in the paas model consumers can develop and deploy software without the need to maintain the operating system so you can imagine how convenient this is to fire up an instance for example if you logged into the Amazon or the Google cloud and start doing your developing it's just so easy and quick consumers have control over the deployed software application and the configuration settings and it doesn't give you to again manage the controller manager underlying infrastructure infrastructure as a service one example is Amazon ec2 web services here consumers access a dedicated physical or in most cases a virtual machine running on the service providers Cloud infrastructure a lot of people use this for web hosting especially WordPress is quite easy to fire up an instance and get it all working virtual machine typically comes with a server operating system consumers complete complete control over the OS and can control the updates um you have control over the operating system application storage you have limited control over the selected networking components such as the firewall that's protecting your particular virtual device again you can't control the underlying Cloud infrastructure probably um neither would you want to infrastructure as a service you've got four models to choose from for iaas you've got the private Cloud the community Cloud public and hybrid for private Cloud the cloud infrastructure is provisioned exclusively for a single organization so you get exclusive use of this you've probably hired a company to create all of the infrastructure for you and nobody else can have access to it and all of your offices and remote offices will have access owned operated and managed by the organization itself very third party or a combination a physical location could be within your premises or it could be located Elsewhere on the cloud Community it's um Provisions for a specific community of consumers from organizations that share common concerns such as security compliance jurisdiction and so on for example would be law reinforcement in this model the cloud infrastructure may be owned operated by one or more organizations by a third party or you could have a combination the physical location and may be within your premises or it could be located elsewhere in public Cloud it's provision for the general public so it can be used by the general public over a network such as the internet um the cloud infrastructure could be managed by the government businesses Academia or a combination foreign physical location is within the premise of the service provider now a hybrid is a mixture of any of these separate entities but are integrated into the benefits for the um of the multiple deployed models example is when the it organization uses a public card as a temporary solution to meet um an excess capacity demand that can't be met by their private setup so I've looked at quite a few things here you need to make some notes obviously because there's a few things to remember for the exam service models software as a service platform infrastructure private community and public cloud and hybrid okay that's all for now thanks for watching [Music] welcome to module 18 lesson one physical security controls I'm going to whisk through this pretty quickly because most of it is pretty self-explanatory and Common Sense really physical security man traps Network closets video monitoring door access controls proximity readers biometrics Cipher locks and a security guard so the physical security control is the measures we take from physical threats basically people trying to get into our data center I guess Ram radio might be included because I've never heard of that but uh yeah physical security examples I've already mentioned the man traps the network closets they reduce the risk of damage or loss by preventing or slowing down physical attack I've actually been a worked uh or been to a few networks Consulting where they don't have any security whatsoever everything's shoved in a Cupboard and the entire company website the financials the accounting all stuck on the server hanging off a cable in a Cupboard and I'm sure you've seen the pictures or may have seen it yourself for real and it's pretty easy to do it doesn't have to be expensive a man trap I've experienced in a internet service provider that used to host some of my equipment basically it's a space it's a door um within a door so you go through one set of doors which it normally has got some type of security keypads or whatever and then you've got a second set of doors you have to go through if it's a manual Man Trap or security guard locks and unlocks each doors and sequence if it's automatic the doors are only opened after getting an identification from the person uh the one I went to you had to do a keypad to get through the front door and then actually pick up a phone and speak to the on-call engineer to get through the second door and it all had to be done by appointment our Network closet is is a room where Network hardware switches switches and routers are installed physical access to the closet is normally restricted by having some sort of security control videos um normally record who comes in who goes out who accesses what and where and it's recorded for a set period of time this can be CCTV or video over IP foreign electronic system I'm sure you've used these in a lot of different places to get in and out of different rooms and buildings and floors and use a granted access door if the door is open for a predetermined amount of time and the entry is recorded the door remains closed when the users denied access that attempt is still recorded if the doors held open for too long then it should trigger some sort of action or alarm proximity reader is basically electronic access where you have some sort of smart card and you swipe your way in and possibly out again as well you'll normally hold the card on or in the reader proximity read normally bleeps or beeps when it has red your smart card if it doesn't read it you may hear a different type of beep and you may have to go and get your car checked or renewed when the user's granted access to the door will open otherwise it remains closed it's pretty obvious to be honest Biometrics refers to remetrics related to human characteristics fingerprint face Iris retina and so on and so forth if you've seen it if you've watched any of the um Mission Impossible movies uh since Biometrics are unique to individuals they're used to verify the identity of an individual before granting access the biometric locks Grant access only if the biometric feature is validated for example scanning your fingerprint keypad and Cipher locks the cipher lock uses a keypad in place of a keyhole use us to provide the correct numerical pin code by pressing buttons on the keypad cypherlock could have four or five push button combination in order to get in uh Cipher code is created at the initial setup but obviously can be changed usually changed every week or every month and the security guard is the whoever's been uh got on the course got qualified and um it has become the security person it has a legal or inappropriate actions all right so covered some following items all fairly obvious I think just to make a few notes for the exam and I'll see you on the next presentation thanks for watching [Music] welcome to module 18 lesson 2 basic forensic Concepts this is one of the new additions to the network plus syllabus and it's basically because of the increased scope for Network engineers and the more formal proceedings we have in um respective Cube and computer forensics so this is quite um an emerging field of um law and evidence and obviously we've got uh forensic investigations going on now in terms of um terrorism and other threats and crimes and um we need to be familiar with some of the basics so what are forensics and computer forensics the First Responders job electronic discovery chain of custody legal holds securing the crime scene high level View some steps in basic forensic process including collection examination analysis and Reporting so what is forensics or what are forensics is the scientific methods and techniques for collecting analyzing and preserving evidence that's the definition can be used in the court of law and if anything's going to be used in a quarter law it normally has to follow a certain amount of um procedures in order to qualify as evidence as we'll see the um computer forensics U.S government organization states are following computer forensics is defined as the discipline that combines elements of law on computer science to collect and analyze data from computer systems networks Wireless comms and storage devices in a way that's admissible as evidence in accord to law and it all hinges on that last sentence really it has to be admissible and we'll go into the chain custody in a bit this uh when I worked in the police it applied to physical evidence in as much as we had to know who first sees the evidence who do they hand it to who examined it after that and so on and we have to have this continuity and it's the same in regards of computer forensics computer forensics help organizations deal with security incidents that have an adverse impact on their business so it could be for internal investigations also security incidents are events that violate the security policies of the organization so obviously some things may not be a crime however sharing sensitive information as regards of your company or take over bids or other information about people at work there can be a breach even though it hasn't um it isn't officially a crime for whatever reason here's a screen grab if you search for um computer forensic certifications the website Tom's it pro has listed what uh for 2017 are the top five uh computer forensic qualifications the certified computer examiner in case which is a um vendor specific the other ones are vendor neutral I think certified forensic computer examiner um gcfa and gcfe I'm not sure that stands for cyber security forensics so um if you're interested in this particular field then there's certainly other certifications you can follow uh just do some research and see what uh the employment prospects are so examples of security incidents include unauthorized access to data attacks through malware or denial of service it's important to understand the technical and legal aspects in order to gather information because you could be will cover first responder in a bit but you that could be you could be contacted by a law enforcement agency told us some sort of um data or even their Hardware that's been involved in the commission of a crime and be asked to take certain steps or be served with the legal notice for criminal or civil court the risk is if you don't have these forensic processes you could lose your um evidence or it could become inadmissible which can be quite embarrassing because um it could I mean the cases last the security professional needs to know the legal aspects so U.S law mandates proper authorization must be acquired before Security Professionals can monitor and gather information so it depends what it is you'd be certain sort of court order or warrant and in the form of a paperwork in order to um take certain action or preserve a certain amount of evidence or hand it over uh organization should have a computer forensic competence established as part of its security policy and you may need to have it in respect of having audits for compliance or certification to work with certain vendors or government departments so the first responder is a person first to be present on the scene after the occurrence of a security incident which if you're the duty network engineer then that could well mean you um you control the damage caused by the incident and ensure none of the evidence is spoiled to the best durability first responder initiates the escalation procedure so you'd inform um the legal authorities whoever that may be and um internal company management and bosses e-discovery or electronic Discovery refers to a pre-trial procedure where the parties exchange the electronically installed information this could be emails exchanged between different employees it could be spreadsheets a video conference calls that have been recorded um anything electronically really that's pertinent to the case and it's different from paper documents because it's not actually tangible um and it could obviously be saved in one place or saved in multiple places over the cloud and have different versions of it some examples for electronically stalled information are as follows emails voicemails documents presentations databases websites and it could be for a certain period like a database copy of a database from a month ago or a year ago or whatever it obviously varies the electronic Discovery process this involves identifying preserving collecting processing reviewing and producing the document to the opposing Council you could actually have to produce it for your own lawyers as well and to prove your case now the gender custody is a document and you could have evidence labels if it's a physical hard drive for example and this would include the person who seized it who they handed it to um I'll go into some of the stuff on the next slide let's um let you know the location of the evidence so if it's finally handed to a and property retention department like in the police property area then um that would be the last person to have signed for possession starts when it was collected requires who collected it the date and time description where the evidence was stored it's not only given an exhibit reference as well certainly if it's collected by an experienced um forensics person it'll have some reference number on it um how it was initially secured which software can be used to view it the transfer history the evidence and here's some evidence labels and not necessarily just for um Okay computer forensics if you can see on the left it's received from and by date time the agency the case number the badge number and then on the right the submitting agency again and chain of custody so the child across today is the transfer history showing the information every person or every normally person could be a department and along with the names and the person signed in the dates and where the evidence was stored and secured now if there's a problem if person a has signed it person B assigned it and then person D signs a label we've missed out what happened one person C held that evidence and if the chain of custody is like broken it means the evidence could be tampered with and then it'll be down to a court to determine whether or not that evidence is still admissible and the evidence um but I've just said that it may not be admissible it could be useless in court all right there's a document or a process called Legal holds used in litigation but it could also be a preservation order basically requires an individual or organization to preserve all information that may be required by an opposing party because of anticipated litigation data should be preserved such as emails um preventing things being deleted because of um a certain period of time has um transpired or expired sorry and there's an Interventional hold on the routine destruction until the litigation end so you know as backups normally get wiped and um replaced with fresher backups then um you wouldn't be able to do that you'd have to keep hold of the evidence if a crime scene is a physical location then the area should be first secured once the area is secured is important together as much evidence as possible normally this person will be properly trained and qualified and just to go through how the evidence is collected photographed preserved and who it's handed on to and in what manner and some types of evidence and not that it applies to computers but um say blood on clothing that has to be dried in a certain way in order for it not to um all go stale and lose all the DNA evidence if the crimes are cyber crime and then the location should be secured to stop the evidence being tampered with it doesn't mention there but obviously if there's remote access available to the device that has to be born in mind as well in case somebody can inadvertently log in and wipe the information a hard drive should be kept in a secure Drive is probably going to become harder and harder now we're using cloud computing uh collect all um digital evidence in a manner permissible to the court it depends on the court obviously when Crumbs are committed the first responder at the scene controls the damage this could well be you as I've said so down to you to use your technical know-how to preserve data as much as possible foreign ensure nobody else tampers with it again you'll be advised by law enforcement as and when they arrive but down to you to stop people walking all over things or picking them up or moving them which have seen happen when I was in the police during the course of the investigation the investigators collect as much evidence as possible the technical city is established from the moment of the initial collection until the investigation finally ends if it has to be transported the data in some way it should be done so securely to prevent tampering again this is the chain of custody uh when the investigations finally complete the forensic report is made available in a format that can be understood by non-technical person and normally because it's been presented to the jewelry if it goes to um a jury trial okay we've mentioned um the legal hold must keep that information into the litigation ends just a few steps in the basic forensic process this should be a process in place according to National Institute of Standards and Technology the following steps collection examination analysis and Reporting collection is the first phase where data is identified labels and recorded and gathered could well be photographed in situ also examination uh it's the data's forensically process using automated or manual methods analysis the results of the examination are analyzed to get answers and then reporting the results are reported details the actions carried out the tools and procedure used who did it and when and why Okay so we've covered a lot here so just to recap we've looked at forensics and computer forensics the first responder electronic Discovery in the chain of custody legal holes securing the crime scene the high level View steps in basic uh forensics collection examination analysis and Reporting so that's all for now thanks for watching [Music] thank you welcome to module 18 lesson 3 safety practices another new addition to the topic and it's something that has been growing over the past few years and so this has become a recognized area where you go and get qualified in a risk assessment or whatever it's called in your respective countries in respect of um certainly data centers the safe storage um manual handling what to do in the event of an emergency a fire or other disaster how to keep um the equipment safe and comply with all of the um different certifications and if you want to be a Data Center and keep people safe also so look at the data center and the need the environment heating ventilation and cooling HVAC how HVAC works typical hot cold oil conditions rack mount servers rack loading power distribution and fire risk the impact of Fire types of their suppressant agents you've got available to install wet pipe dry pipe and gas how to lift stuff up without getting injured anti-static it's funnily enough anti-static if people laugh about it and don't think about it but it can actually fry vital components in your devices stabilizing the Iraq and the material safety data sheet which is another item added to the syllabus the MSDS all right I'm sure you've heard the data centers and if you're very lucky you've actually got to work in one or will be working in one great place to work there's a definition on Wikipedia it's a facilities used to house computer systems and Associated components such as telecoms and Storage generally includes redundant backup power supplies Communications environmental controls EG air conditioning fire suppression and various security devices why do we bother it basically helps organization centralize the entire Computing resources into one location where they can have a uniform procedure for insulation upgrades out of hours a redundancy a whole bunch of stuff uh reduces the TCO by consolidating all your power and cooling otherwise you'd have to have 10 20 30 40 racks spread among different departments or different buildings or different cities making things pretty difficult to control racks and rackmatic servers are used in data centers at the moment I'm sure the future will uh have something completely different you've got the servers storage arrays and power distribution units all the other devices and internal components generate a lot of heat the heat needs to be removed because it obviously affects the electric equipment to the point where it reaches a threshold that it can no longer function and then the device will fail and you may have had this on your home computer if your CPU fan has stopped working or this tumors dust or dirt inside your equipment then it starts to lock up and finally fail I know that's happened to me since heat effects of reliability we need to keep it cool this requires removing the hot air and moving in cold air just like your PC chassis but on a much larger scale I'll turn cold air within the data center shouldn't be mixed and for this reason you've got the hot oil and the cold oil Arrangement this is for your ventilation if the cold air mixes with a hot air without going through the equipment then it becomes useless so HVAC stands for heating ventilation and cooling which is an entire set of systems procedures best practices and companies that will help you plan and manage and install all of this provides the optimum temperature and indoor air quality so you've obviously got to have an environment that works best for the equipment but also the engineers can go in and manage and survive in the HVAC system not only keeps things cool and keeps things humid obviously not too humid but there has to be a certain level of humidity in there and removes contaminants from the air also cold air is pumped from the HVAC system into the cold aisle as an as an input for the servers the server is pulling cold air from the front to cool themselves and they exhaust hot air which goes into the hot tile now my experience when I've gone to Data Centers is the the better ones I've got doors to get in and out of the cool aisle the Hostile um they're certainly the ones I've been to don't have the doors so you'll be walking through an area that feels quite warm you'll open the door to go to the front of the servers to connect or do whatever obviously shooting the door behind you and it'll be very cool in fact you'll probably need to wear a couple of layers of clothing the AC duct carries the hot air from the hotel to the HVAC to cool it again and exhaust it elsewhere typical hot cold oil conditions the cold air temperatures range from 55 to 78 Fahrenheit they haven't listed this in Celsius so I presume this is for the American viewers the hot oil temperature goes from 73 to 96 Fahrenheit and the amount of heat carried by the stream of air exiting the heat load should be 15 to 20 degrees Fahrenheit rack mount servers I don't know if you've seen many of these I've seen a lot over the years the rack contains the servers the servers have a different form factor than your normal desktop servers these are these obviously need to be compliant to fit into a rack taking over so many um units uh use they call it sometimes one two and so on they need to have the correct eyes so you can screw in the screws to hold it into place securely front and back and most of them actually you can pull open so it pulls out from the rest and you can do various things without having to shut down the server or the cables coming loose larger up Mount servers and Equipment are stored at the bottom so the heavier stuff at the bottom to ensure the rack doesn't tip over Rock loading should not only seed the weight rated capacity of the raised floor to ensure that the race floor doesn't collapse because it's overweighted everything has to be documented planned and measured so you spread load over inside one rack and among a multitude of racks so you can have the heavier stuff going at the bottom of 10 different racks the next heaviest goes on top on 10 different racks and so on rather than having one rack with all the heavier stuff because it could if it breaches a loading it's obviously going to break through the floor uh the power distribution your data center is normally connected to multiple power grids um and even after that you could have the one the one I used to have my equipment at had um massive generators that would take over and it wasn't one generator the generator had a backup generator as well so there's three levels of redundancy in case there was a power cut for whatever reason if you've got two grids if power is lost on one grid and certainly where I live in Australia you get power Cuts quite regularly which is a strange phenomenon now to experience nowadays for devices with redundant power supplies power comes from separate circuits providing redundancy so it would be um it wouldn't be great redundancy to have your redundant power supply both connected to the same extension lead because if the extension lead goes down or the power supply providing power to the extension lead then you lose both your power supplies redundant and Main as a data centers power requirements are determined by taking into account the power requirements of all the equipment and you've got a feature um future growth so you can't just plan for what you need now you need to plan for however many years in the future in the company's business plan uh you need to ground all equipment separate to um other grounds fire and demand for the power increases with the um amount of equipment a lot of the cream equipment with increased power consumption I can find a small spaces and susceptible to fire accidents again this is down there due to heat obviously fire will be catastrophic data centers are fire detection systems that detect the fires where they detect smoke I think before the fire you've got portable fire extinguishers for engineers to use if they somehow set something on fire or see a small fire data centers have emergency power off switches which are big red patents on the wall that cut off all power obviously if you do that it's um a constitutes an emergency because all the servers don't really um deal with hard power shutdowns very well they normally need to be correctly um shut down following procedures faster person agents put out the fire you've got to choose the correct one obviously if you even if you go to a local hardware store and choose a fire extinguisher there's some for um the kitchen some for papers and some for car fires there are three types wet pipe dry pipe and gas the wet pipe is basically a water that's held within the pipe under pressure and it breaks a little seal which you can see in the picture there the little red seal and that um when that breaks it lets the water come out and obviously soaks everything with water and that's the end of your equipment and it will bring your data center down the drive pipe is the same as a wet pipe but the water's not kept in the pipes and the reason is it accumulates moisture and if there's a drape it can damage the equipment and obviously um could cause rust since the dry pipe is a water-based system the disadvantage is the same as the wet pipe now you've got gas suppression suppression which is the norm in your data centers it basically starves the fire of oxygen and the fires need oxygen in order to generate the Heat clean agents such as fm200 remove the heat from the fire and here's some large industrially scale heat agents and inert gases such as carbon dioxide deprive the fire of oxygen you do get immediate recovery of business operations you've obviously got to vent the area before people are allowed back in otherwise they'll just pass out and and you've got to have training for the staff it doesn't actually mention I didn't put in here but you obviously need an evacuation plan so that there's normally a diagram in several key places and and signed exits as mentioned in the syllabus but I just thought it was so obvious because we all see them wherever we go even coffee shops have got fire exits of fire escape plans lifting techniques well you can see this guy here is bending his back not his knees which isn't a recommended way to do things easiest way is to adjust houses through improper lifting don't really lift the equipment if it weighs more than a quarter of your weight lift with your legs with a straight back obviously if you have injuries especially back injuries then don't attempt it and a lot of the time there's lifted equipments there that will oyster for you or hold it in place while you screw things or unscrew them and Slot them in anti-static static electricity as I mentioned at the start will fry various components and that's happened to me when I've installed motherboards and other devices I've just heard a Little Fizz and some things um something's broken so use anti-static devices there's anti-static bags and also wrist straps that you can connect to your wrist and then connect to an earth somewhere that will prevent the um causing the spark somewhere because as we walk around we're generating electricity static electricity stabilizing Iraq is important to have a correctly stabilized rack with the um fate which are all adjustable racks are not stable or likely to collapse at any time um you put your large equipment in at the bottom and the lighter at the top there and moving on to another syllabus item is the MSDS the material safety data sheet which you'll go into this is a document that contains information about hazardous chemicals used as a primary means to communicate and the chemical hazards to staff I presume you'd go in some sort of training course for for this not um not just read something on a wall preferred by the manufacturer or supplier of the chemical you have to make the MSDS available in your workplace for each hazardous chemical or a mixture of such hazardous chemicals it should be ready available to all those who may come into contact with such hazardous chemicals the occupational safety and health administration and I presume these are American different countries will have different organizations or Administrations they're part of the US Department of Labor create the hazard communication standard to ensure that all um chemicals that are hazardous are evaluated and the information is correctly passed should be in English this should be include 12 items mandated which will go through briefly the name of the chemical the physically chemical pop and properties such as color and odor so you can recognize it if it does have a color a lot of them have odors added such as their natural gas has an odor added certainly did in the UK so you could smell it if there was a leak and before that and people didn't know that the house was full of gas and uh lit a cigarette and that was the end of them physical hundreds uh hazards such as explosiveness or could it react with something uh health hazards such as corrosive to eyes or skin you normally have that in a diagram as well primary ways you can enter your body such as always breathing allowable limits of exposure before you get seriously injured or die carcinogen precautions before you use it masks or goggles special equipment and do you need any gloves protection and Engineering controls first aid if it all goes wrong normally as the number of the Emergency Services the date when it was prepared the document and the last revision contact details of the person who's responsible all right we've covered a lot here and it's all your health and safety stuff your data center your HVAC hot and cold aisles and a correct loading of your racks fire risk fire suppression and the impact your type of Agents lifting without injuring yourself or others you're anti-static and rack stabilization and your MSDS so that's all thanks for watching [Music] foreign lesson one common wireless issues and we look at signal loss interference signal to noise device saturation bandwidth saturation untested updates getting your SSID wrong so you can guess how to fix that one power levels open networks Rogue access points wrong antenna for your device incompatibilities wrong encryption and bounce most of these are pretty Common Sense actually but I've put these in because um it's on the syllabus and if you've got a home wireless device or even you've used Wireless on your mobile phone you probably have to troubleshoot most of these issues um but we'll cover them nonetheless just in case signal loss you've got no signal or low signal there's connectivity and there's no connectivity when there's no signal there's latency and inconsistent connectivity when the signal strength is low client devices closer to the access point especially when you're at home actually if you've got a your wireless access point in a different room and if you've got an older house certainly in the UK most of the walls were made of um thick concrete and uh they built the houses to last there was no or very few false walls inside houses with just plasterboard or wood um obviously you can install um a booster as well you can install something in your power unit and it will boost the signal or act as a repeater ensure there's minimal obstructions metal studs is another one that will reduce your um connectivity or signal ensure the antennas allow communication as well sometimes the antennas come in a box or um they're not attached or they're just pointed in the wrong direction interference other wireless devices are using the same frequency uh you can also have interference from microwave ovens and cordless phones it tells you this in the documentation but most people don't read it when you're installing your wireless router it'll have a pictures of the kind of things that will interfere with your signal you'll get latency and inconsistent connectivity avoid interference pretty obvious as I said and but you can avoid having your devices near to these things like your ovens or cordless phones um you may be able to change your channel as well if it's got the same channel as your cordless phone uses overlapping channels because of the wireless access points are used in the same frequency there's automatic channel selection normally on your devices but if you have any reasonable amount of ability you should be able to log in and change your channels uh avoid uh you can correct it by avoiding the manual selection of non-overlapping channels signal to noise ratio it's the ratio of the Wi-Fi signal to the outside interference or noise noise is in respect of Wireless have a negative impact on your wireless signal other Wi-Fi signals don't count as noise this again will give you connectivity issues or latency signal levels and noise levels can be visualized as heat Maps the ratio of 10 to 15 decibels is considered unreliable 16 to 24 is weak issues can be avoided by increasing your signal strength and decreasing the noise I told you all this stuff was obvious device saturation is when more wireless devices are connected to your network you'll get a decrease throughput that's probably your fault for letting your kids have access to phones at home or other wireless devices bandwidth saturation is when one or more devices transmit a large quality of quantity of data um I would imagine received also so if somebody in is there watching YouTube in another room in the house and that'll do it untested updates um updates can obviously break things if they haven't been uh correctly tested especially with regards firmware I've even recently installed a an SSD drive in my home computer and while I was just researching it I found that the latest firmware drive from the manufacturer actually was wiping everyone's data which is catastrophic for most of us and the manufacturer was aware and they said they were releasing an update but the problem is if you downloaded the update it was too late for you back up your last working config not sure how you do that with your firmware actually but you can research that yourself wrong SSID all you need to do because they're case sensitive you could have the wrong case or just mistype something a lot of the time when you type these out you can't actually see the letters you're typing unless there's a an option for you to do that so you could well have typed out the incorrect password but you can't see it avoid having the client device and the access point set to use the same SSID power levels uh users will experience a big coverage area or small coverage area because of low power levels and access points big coverage areas occur because of high power levels and access points and avoid it by adjusting the power levels for a good coverage area open network is an unsecured wireless network you used to see a lot of those around but most people now have become Savvy or the default settings on the home routers I've got security chosen automatically unauthorized devices May connect to the network if it's insecure so obviously change the security settings if this is the case Rogue access points as an authorized access point installed on the network normally employees uh just for a bit of convenience will go into their desk and plug something in to get wireless access malicious attacker can install Rogue access points uh thus getting them access to the network wrong antenna type signal coverage depends on your type of antenna so you could have no signal or poor signal or um a good signal but far away from the access point okay omnidirectional and directional are two main types of antenna omnidirectional gives you 360 degree degree patterns suitable for inside an office conference area directional will give you a signal in a particular direction so your coverage is limited to that One Direction you got a yagi parabolic grid patch and panel antennas the jaegi and parabolic grid are used to connect one building to another you must have line of sight so if somebody's got a tree there or something else temporary or permanent then it's going to cause you issues that you'll have to troubleshoot and if you see if there's incompatibilities users may not be able to get access to the WAP the settings may be incompatible standard supporting if you've got a very old um Wireless car that you've got on your device a PCI card or USB it might not be compatible with your other device so 802.11a is not compatible with 11b and 11g you've got to look at what is compatible so B is compatible with G and vice versa some are backward compatibility compatible others aren't uh wrong encryption you may not be uh get a connection with the wireless access points the client device and wireless access may have different encryption settings so you need to check that um what's configured on your access point is matching on your wireless card or wireless device whatever you're using so do configure it correctly examples are web WPA and WPA2 bounce is when your signal bounces off an obstacle without reaching the destination you can get weak or no connectivity you need to remove the obstacle obviously sometimes that's easier said than done so if it's a big thick concrete wall in your house don't don't knock it down because your roof will fall down you need to either get some sort of booster or um move where you're connecting from or just find a alternative connection type such as connecting through the um ethernet devices that were plugged into your power all right so we've covered a lot a signal loss interference signal to noise saturation bandwidth saturation untested updates wrong SSID and your power open networks Rogue access points the wrong antenna type incompatibilities are on encryption and bounce that's all for now thanks for watching [Music] thank you welcome to module 19 lesson 2 Common copper cable issues that's a mouthful so some of the common issues you'll experience as a network engineer our shorts opens incorrect termination crosstalk Emi distance limitations attenuation the cable issues shorts is basically short for a short circuit it allows the current to travel in a path that wasn't intended and the cable wasn't designed for a couple was in the cables are insulated so they don't come into contact with each other if um there's some sort of issue a lot of the time it's because it's frayed somebody's bent the cable around a Bend or just done something with it or folded it too many times and unfolded it then the cables can touch each other and then you've got a short circuit you depended on how bad it is you'll have intermittent connectivity issues you could use a TDR that will locate the short in the cable this is one of your troubleshooting tools that you could use an open refers to an incomplete electrical circuit in which there's no current if one of the copper wires inside the cable is cut or just broken for some reason then you've got an open circuit you would normally then have no connectivity again you can use a TDR that can be used to locate openings in the cable incorrect termination generally happens when you've made your own cables or your cable engineer has done it and just made a mistake or done it too quickly or just not and been watching what they're doing and it's obviously human error then don't happen it doesn't happen as much in um professionally made cables so you haven't properly terminated as per the standards you could have got the wires mixed up or not squash the um the RJ45 connector onto the wires correctly and it's a bit of an art to it so you could have no connection or intermittent connection issues straight through cables should be terminated either using t568 a or b crossover cable has got a on one end and B on the other so pins one goes to three and two goes to six on the other end use the cable tester to check if your Cable's properly terminated and what type it is crosstalk is when the signal from The Wire interferes with the signal on another wire less of an issue now with modern um shielded twisted pair uh cables you measure with the cable tester or TDR again the issues avoided if you buy a professional cable basically because it will be twisted properly two types of crosstalk that you may be asked about in the exam near end and far end and near end is refers to the crosstalk that occurs at the terminated end of the cable where the crosstalk has been measured so this is where you're doing the measuring occurs near the connectors terminating the cable far end is um on the far end of the cable from where you're doing the measurements occurs near the connectors terminating the far end of the cable electromagnetic efference is normally when you've laid the cable yourself and it's gone through or near some device that emits a strong error signal an emo signal also called radio frequency interference generate generated um by fluorescent lights electric motors dynamos things like that so it could happen in a workshop or when you haven't properly housed your cable or it's not running under the floor and you're running it through the ceiling and it's going through the um fluorescent lights data transmission of copper cables is um obviously disrupted when it's exposed and it could be intermittent it could be fine during the day and then later on in the evening when somebody starts turning the lights on it could be affected avoid if you separate the power source from the cables or by using shielded cabling you may have to buy a special type of cabling if you're running your cables through devices with a lot of very powerful um electrical signals obviously there's distance limitations per cable lost the signal when it travels over a long distance you could then have connectivity issues so if you're running your cable over 120 meters when it's recommended 110 then you may well have issues attenuation or DB loss refers to a loss of signal strength the signal strength is measured in decibels uses experience degradation in network performance you can avoid it by um using cable runs within the maximum supported distance using a signal booster you probably need specialized advice for this to be honest if you're installing in a commercial premises remove broken or damaged cables and miscellaneous of the problems uh verify the cables are present and plugged in yes I've been asked to troubleshoot devices when somebody hasn't actually put the cable in yet it hasn't been installed at all or somebody's removed the cable for some reason because they want to use it somewhere else and not realized that that is connecting to an end user or a server or some of the device make sure the network adapter is enabled and it has a valid addressing sometimes devices have been up for years and um millions of packets have been passed in in and out and it just needs resetting or rebooting or the address needs and refreshing on it it just happens sometimes every period of time make sure disabled ports are enabled for connectivity sometimes ports are disabled for security and you could plug in a new user into a certain port on a switch for example but that Port has been disabled you can have bad cables again sometimes we bend them or just over time for whatever reason the cable goes bad misconfigured switch Port it could be the wrong um duplex setting or speed setting or something else on there and it may not work misconfigured network card or a network card that's failing or failed software drivers I've mentioned elsewhere that can cause huge problems and it's not a problem you can actually easily see until you start doing a bit more research all right so we've covered shorts opens termination crosstalk Emi distance attenuation and other problems that's all for now thanks for watching [Music] welcome to module 19 lesson 3 common fiber cable issues so look it's troubleshooting uh supported distances categories of multi-mode fiber the bend radius dirty connectors I think you can guess what that one's about attenuation a wavelength mismatch fiber type mismatch so the bottom line with fiber cables is uh if it's faulty it can't transport data it tends to be either a working or not working situation whereas with copper you may well have a period of time where the the performance just deteriorates when you get in packet loss or intermittent um connectivity and you normally easily troubleshoot that by just swapping the cable out if it all works then it points to the fact that the cable was faulty and they're so cheap you just throw them away obviously um fiber cables are not so cheap first place to look will often be the LED next to the ports where you've plugged the cable in if it doesn't light up then you've got a number of possible reasons the cable's not um plugged in properly at both ends the cable could be broken somewhere now here's um the troubleshooting flow chart for fiber cable um well worth maybe just printing the screen and just following it through plug it into a different port does that Port light up then and it shows you it's a problem with the port um just a few simple troubleshooting steps really all right don't look into the cable when you've got the other end plugged in because the laser will go directly into your light and it could cause damage so use um you could well you could actually point it at um a white object or a wall or at your hand um but read the documentation that comes with the cable to make sure you're doing the correct thing there are obviously electronic devices that you can also use when you can connect two devices such as a server adapter to a switch using a fiber cable the TX Porter one end should always be connected to the RX Porter the opposite end normally you'll get a housing that both ends of the cable will connect to and that can only plug in one way to the device not always the case and obviously there's different cable types all over the world but um normally you'll um it'll be designed to be idiot proof so we don't um cause that issue if you connect it the other way around you'll have no connectivity and then um it'll show no connection as supported distances multi-mod fibers with 50 microns and 62 microns can support data up to 500 meters and 175 respectively again read the label it comes with your cable in um you might you may well be lucky enough to have a professional company coming into your cabling for you and then again you may have to go and swap some cable out or install a new device without the aid of this company so you do need to know multi-mad fibers are categorized further by Optical multi-mode or om designator these are labeled from om1 to om4 just check the uh table and um you've let you've normally got a label on your cable as well to see what you do however it's stamped on the side and just check the specifications and allowances when you troubleshoot in check whether the cable supports the speed and distance of the link between the devices Bend radius most fiber optic cables are made of glass a sharp Bend at some point they are pretty flexible but if you bend it too much it will break the glass the bend radius refers to the smallest bend a cable can withstand again if you start wrapping this Cable Round and Round a pole in order to take up the slack then you could well check and break the bend radius and rendering the cable um unserviceable to avoid issues don't bend them obviously or more than you have to the otdr can be used to check whether the cable is damaged damage cable obviously needs to be replaced hopefully that goes without saying um the broken cable some people put them in a cable box if it's broken make sure you dispose of it in um the legal the legal manner so you can't throw it onto a fire usually you'd have to have it professionally uh destroyed or every cycled if you've got dirt because it uses light on the fiber cables if you've got dirt on one end it will cause um problems High loss and reflectance clean it using the cleaning methods and supplies provided with the cables don't wipe at the end of it on on your trousers attenuation signal loss over the fireball optic cable following could be the reasons it could have been over stressed during installation improper termination improper splicing if it's been spliced somewhere could be broken fiber again you can use the otdr to locate the faults wavelength mismatch fiber cable uses wavelengths longer than a normal light it's usually around 850 1300 or 1550 newton meters multi-mode fiber is designed to operate at 850 to 1300 single mode 13 10 or 1550 the wavelength is used for transmission on the wavelengths that must be tested for Signal losses in the cable plants now when the mismatch fiber cables are coupled the incompatibility of the core sizes results in signal loss now there's no problem if you're transmitting light from a smaller fiber core to a larger one but the other way around and you'll have signal loss the signal loss can be around 20 DB when a couple when we could pull a multi-mode fiber to a single mode again read the documentation that comes with all your cable in so I've looked at fiber cable supported distances and categories the bend radius dirt on your connectors attenuation and wavelength mismatch and fiber type mismatch that's all for now thanks for watching [Music] foreign 19 lesson 4 common network issues there's actually entire books been written about troubleshooting Networks and from PC switches and routers and it's something that requires a bit of experience common sense and often a plan and sometimes a bit of good luck as well and guesswork we're going to look at common things that normally go wrong day to day incorrect default gateway broad Customs duplicate IP address your duplex and speed mismatches incorrect vlans Hardware failures and DHCP DNS interface misconfiguration cable placements power failures and then less common MTU black hole Nick teaming issues so you can create default gateway um it depends if there's been a change of default gateway if the device um that is experiencing the problems has had any changes or um somebody's gone in and configured something so it all depends on the questions you've asked really but if you've got the incorrect default gateway then all traffic from your host device is going to the wrong location and Layer Two devices such as switches also are normally configured with the default gateway but you should be able to Ping from the um switch whatever the VLAN is to the default gateway when you're installing it just to check it's working so the IP address assigned to the default gateway may be correct and you can check your IP configuration settings on your windows or Linux um device obviously to fix it put in the correct default gateway and make sure nothing's changed on the default gateway broadcast storms users can experience a degradation and network performance and it can actually bring down the entire network so the network is flooded with broadcast traffic could be a switching Loop it could also be a faulty network card that's just sending a huge amount of traffic out and you could troubleshoot it with Wireshark and other programs and Cisco provide um a whole raft of tools uh obviously having spanning training switches will help solve the problem it's normally there it's normally on their body faults duplicate IP sometimes somebody doesn't release their DHCP address it's been on there too long or stuck for some reason or I've seen people manually configure an IP address on their system for some crazy reason I don't know why they did it and it's caused a mismatch to avoid it you can change the IP address of both or one of the hosts and normally um asking for it to be provided by DHCP which most devices use speed and duplex mismatch you can have on your host or on a switch in fact on a router as well you'll have slow or degraded Network performance or no connection no connectivity at all and you could have different port and speed settings you could have 100 full duplex on one side and 10 Meg half duplex on the other side and you're going to have problems normally you'll see issues on the LED of the network card as well and you could have um error messages coming up on your router or switch console and on your PC so common causes when negotiation is enabled on one side and disabled on the other it's reliable to manually configure network speed and duplex settings for the server and other critical links now you may use Auto negotiation the networks I've worked out they they generally didn't they had hard-coded and speed and duplex settings for all devices uh incorrect VLAN if you're on the wrong VLAN you may have no connectivity or not be able to access the resources that you need because it's in a different VLAN configuring devices is normally the switch Port the end devices don't have VLAN settings as a general rule you would configure the switch port to be in the corrective VLAN and make sure it's not blocked that VLAN is unblocked for security reasons on the switch trunk port Hardware failure this is a whole raft of things that could go wrong intermittently or just completely break and one of the components of a device may have failed or an entire device you identify it with your troubleshooting methodology and you can replace the faulty device or the faulty interface DHCP if this server has been incorrectly configured then you're obviously going to have issues you could have one person affected or the entire um organization you could exhaust all of the IP addresses on your DHCP pool you could also indicate that you've got some sort of attack going on some Rogue DHCP server or the devices causing issues we've addressed that elsewhere DNS obviously for DNS lookups you need to have the correct device configured a host can be configured with the wrong DNS server either because you've misconfigured the DHCP server or somebody's hard set it so ensure the host is configured with the correct IP address of the DNS server on Windows you could issue ipconfig space forward slash all and it will show you your DHCP server address your DNS server address IP address and a few other um settings that you may find interesting if your interface is incorrectly configured you'll have no connectivity or intermittent you could have the source um or destination device may have an incorrect IP address or subnet so if if for some reason you'll um router interfaces on either end have been put in different subnets then you're not going to get you're not going to get connectivity check the ipn subnet mask of both source and destination and check it against your design documents cable placement you could have slow performance and it could be close to a source of Emi which we've already discussed power failure obviously that's going to cause issues either with the device or part of the network or the entire network and most um the higher end switches and routers have redundant power supplies so that if the main one goes down the second does backup one takes over MTU backholes this is a maximum transmission units for your IP packets and it depends on configurations it can also happen with routing protocols such as ospf um which is outside the scope of this course if the packet's been flagged as do not fragment then the router is expected to send an icmp message destination unreachable back to the host that sent the packet and the router drops the packet and doesn't send the icmp message then the host to the host and the router is referred to as a black hole router you can check the interface MTU on your routers when you do the show interface or you can add um some troubleshooting software if it if you don't already have it you can use a ping utility or you can use a trace route you can send different ping sizes and certainly on Cisco routers you can go into a detailed menu of options or send a ping packet of a certain size to see if you're losing packets Nick teaming for user experiences a degradation in network performance it could be a Nick teaming misconfiguration this is generally done a lot on servers and different vendors have different terminology for Nick teaming so again check your documentation uh generally you'll you'll aggregate various Network Cards into one logical connection um so you could have broadcast uh storms there'll be other issues as well with spanning tree and um other things to prevent the Nick team from becoming multiple links you can use Link aggregation control protocol which is used on routers generally all right so incorrect develop Gateway broadcast storms duplicate IP and speed and duplex VLAN assignments on your switches check your documentation for that and your configurations should say Hardware failure sorry misconfigured DHCP and DNS interface misconfiguration issues cable placements power failures empty black holes and Nick teaming that's all for now thanks for watching [Music] thank you welcome to module 20 lesson one change management basics we're going to look at what is a change what is change management types of changes and approval processes what is documentation in respect of change management what is a maintenance window what is configuration procedures or what are what is a rollback what is the potential impact what is the notification to change now change management is a new addition to the network plus syllabus it actually dates back to you can trace change the management back to the 1960s and now it's a recognized um qualification and a whole area where you can gain employment as a change management change manager so you could Google change manager and ITIL which is the it infrastructure Library but this is bringing it into alignment with prisoners practices where we're managing um changes and problems also when I worked uh Yellow Pages in the UK there was a whole Lotto team looking at um change management problem management so there's systems and procedures for everything looking at what we're doing why we're doing it who authorizes it if there's a problem what caused the problem how do we stop the problem happening again and it makes the entire uh business procedure and business run more professionally and it cuts down a lot of unnecessary procedures blaming Communications and debriefing and makes the organization work more efficiently changes any addition removal or modification or configuration that could have an effect on the IT service so this is why we need to have a set of procedures in order to plan for a change rather than somebody just rebooting one of the main cool routers on the network at the busiest time of day we need to have some sort of procedure so change management is a set of processes that governs and controls the aspects from start to finish it reduces the risk disruption and impact on the business we could refer to it as CM for short so CM aims to use the defined standards and methods and procedures across various teams of groups so we're all basically singing off the same hymn sheep this is the ITIL the it infrastructure Library which we actually host and some of the one of the qualifications on howturnetwork.com I highly recommend it because um it people now can't just rely on being technical they need to have an understanding of how they slot into the business and how the business works the it works as part of the overall business utility breaks into service transition service design and service operations and you can see some of the um things I mentioned here you can see change management is highlighted there's problem management Knowledge Management Service testing and validation and you slot this into your business how your business works and how it's going to benefit it so change management includes a risk assessment reducing change failures properly implementing any changes looking at business timelines and service level agreements it gives you better control a clear plan for reverting if there's an issue I've actually seen this when I had my website hosted with a different service provider somebody did a change to one of the tables on one of the databases and it caused outages for around three days and I know some people went out of business it was just an absolute catastrophe and they didn't I don't think they had a change management procedure in place otherwise they could have backed out quite quickly I'm managing Communications this is important where there's a central person is responsible for from communicating what's going to happen when it's going to happen and then they communicate um just before it happens and then after to say the changes happened and it was um a success or failure on what's actually um the procedure afterwards for following up changes can be performed to adapt or change business needs Hardware software it could reactively Implement a fix if there's some sort of major issue or bug or attack on the network normal changes for example a a normal configuration or server maintenance and something that it was generally expected standard change is pre-approved changes that don't require approvals these are things that just aren't going to cause a problem usually for example um swapping out a redundant power supply it's just not going to have any impact and it's been tested for um in the past risk associated is low and does not have enough adverse adverse effect on the business emergency these are changes that are implemented on an urgent basis through and remediate a problem it's normally Network effect in business affecting and it has to be done urgently you need to have approval off um the emergency change Advisory Board and they'll normally have either a video conference or a quick meeting in order to talk about the impact on the business because you need to look at the entire um structure documentation a change request is documented using applications there's a variety of um applications you can use the documentary change request is caused a change record it could be online or printed issues to track the chains throughout its life cycle from beginning to end this is so we've got an audit trail of what happened and who did what and who approved it and Etc the change record contains key details of the change including detail tech technical implementation the the technical parts will probably be read by the um the it managers and Technical team but they're there um for the record key details is who requested it why did they request it what's the outcome what's the point of doing it is there a business benefit or is it going to prevent something more serious happening what are the risks involved what resources that includes the teams human resources and physical and software resources for example a network card needs replacing or an update required for the software who's responsible for building testing and implementing what's the relationship between this change and other changes is it one of a series so the effect of one change on another for example if you update a VLAN on a certain device what devices what physical ports are going to be affected is the VLAN going to be propagated on other switches or does it need to be blocked maintenance window I'm sure you've heard of it's an agreed period of time in which is going to have minimal disruption normally done on the weekends or out of hours just depends on your business uh procedures the author authorized maintenance Windows predetermined and pre-approved to carry out the change a lot of the time um an alternative our server is used or whatever um you could have some sort of load balancer used on all traffic is just sent through one of the load balances so the change could actually be transparent to users generally changes during weekdays are scheduled after business hours critical changes Friday nights and they can run into the weekend so you can roll back and recover if there's an issue or changes to service assets and config configuration items are recorded in the configuration management system uh server can move from pre-production to production with a formal sign off before it's accepted into production such changes are to be documented for timely support so everyone needs to know about the fact this new server has been introduced the configuration settings and what the possible risks are and what we do if there is a an issue our rollback is basically going back to how we were before this change happened not always possible obviously especially if something's completely broken and has to be replaced and then the replacement for example is broken also okay so worst case there's a site failover or business continuity plan may be invoked this is if the entire core system goes down is there some sort of backup in place or what do we do looking at the impact there's a matrix low impact and low risk category for going all the way to category one which is high impact high risk and it's a critical category low medium high and critical the notification to change is published with the details of the change activity the window of the change obviously it only goes out to the people that are going to be impacted all right so we've looked at change change management types of changes and approvals what is documentation what is a maintenance window configuration procedures and rollbacks impact and the notification to change that's all for now thanks for watching [Music] thank you welcome to module 21 lesson one Internet of Things Technologies this is one of the new subjects has been added to the latest uh come to exam they just expected to have an overview of what these things do rather than any detail because there's quite a diverse array of protocols here said wave and plus Bluetooth which I'm sure you've heard of NFC uh infrared RFID so Internet of Things it's a network of devices appliances Vehicles physical devices and many of them work with sensors or softwares so for example when you're uh so let me go down there's a car here actually you'll have a sensors on your car I know I didn't want any awards for drawing centers on your car breaks uh which has been detected by a gold goes into a CPU of some sort when it detects it the wear is down and say you've got 30 left then it will communicate to the uh garage a computer in the garage that will all down whatever part you need from the manufacturer that will go to the garage and then you probably depending on how advanced the car is have a notification that your tires are worn or your garage next time you take it in for a service we'll have the part in stock and um we'll be able to replace it that's just one example of The Internet of Things there's many of many of those and it's just a phrase that was coined several years ago said wave is a Wireless Communications protocol used mainly for home automation for example your lighting your security your thermostats to set it and all your favorite settings works over a mesh networks all the devices are um interconnected and is controlled by a keypad or you can have a key fob of some sort and plus it's a wireless communication protocol again monitor sensor data this could be your heart rate tire pressure television any number of things and it's created and managed by the ant Alliance it's actually a subsidiary of Garmin who do uh the satellite technology a Bluetooth mesh adopted in 2017 it's many to many Communications so the receiver can be a thing a group of things or many things for example you'd compare that to the unicast multicast or broadcast all messages are encrypted and authenticated so it's pretty secure are you sorry you can ignore that one near field communications a set of communication protocols you're probably using this already it allows two devices one's usually a smartphone to communicate now you need to be within four centimeters of each other so you have to be pretty close use for contactless payments I know on my phone I can enable it to act as my card credit card or debit card and swipe for my phone instead of my card quite handy if you've forgotten your wallet somewhere as well and you need to pay for something infrared I'll go I'm sure you've heard of that we used to have um this used to be the competitor to wireless where companies would add an infrared communication module on top of their building and as long as they had line the site they could get high-speed Communications with another building then I can't remember what the range was but um it fell by the wayside really it's similar to visible light but slightly longer wavelength for example your remote control you click that and per second of holding down the button it sends out 38 000 signals used in Internet things for medical Diagnostics fire detection remote gas leak detention air detection RFID you probably see this if you saw the uh the newest not the newest porn film a bone film um with Jeremy uh I forgot his name now JB right now we had one of these inserted in him and they tried to uh unfortunately tried to shoot him with a missile so I had to cut it out let's um yes it's essential to the operation on the Internet of Things allows computers to manage all individual things this is compared in the picture to a grain of rice so it's pretty smart uses Emi fields to identify and track tags it up and attached to objects the attack can actually contain the electronically stored information so this is what's used to Target pets for example when will a pet gets lost somewhere it can be tagged also using tracking Vehicles if you've ever seen a production line there's tags inserted on the vehicle and that updates the entire production system as to if it's going too fast too slow and when to expect the next vehicle along all right so we've covered just in brief the Z Wave amp plus Bluetooth NFC IR RFID just you need to be aware of these in case one of the questions pops up in the exam that's all thanks for watching