Welcome back to the Cisco introduction to networks lecture series. Today we're going to focus on module number four which is looking at the physical layer of the OSI model. The objective of this module is to explain how physical layer protocols, services, and network media support communications across data networks.
So we will look at How you can describe the purpose and the functions of the physical layer? We will look at the physical layer characteristics. We will look at copper cabling, UTP cabling, fiber optic cabling and wireless media.
So first we will look at the purpose of the physical layer. Before any network communications can occur, a physical connection to a local network must be established. This connection could be wired or wireless depending on the setup of the network. This generally applies whether you are considering a corporate or office network.
A network interface card or NIC connects a device to the network. Some devices may have just one NIC while others may have multiple NICs, which could be wired and or wireless. For example, most of home computers will have one NIC, while servers and some network printers and devices may have multiple NICs. Not all physical connections offer the same level of performance.
And we will learn this as we go through this module. So the physical layer is responsible for transport bit across the network media. It accepts a complete frame from the data link layer and encodes it as a series of signals that are transmitted to the local media. This is the last step in the encapsulation process and the next device in the path to the destination receives the bits and re-encapsulates the frame.
and then decode it what to do with it. Remember the physical layer is part of the OSI model and so we're just looking at that OSI stack and just focusing on that physical layer component. Physical layer characteristics.
As I mentioned in the OSI model we have the application, presentation, session, transport, network, data link and physical. The physical layer is the bottom one on the stack. The TCP IP model will cover the application, presentation, session, transport, network and part of the data link. While the OSI model also includes the physical layer standards.
that are implemented and governed by these organizations such as ISO, EIA, TIA, ITUT, IEEE, NSI, etc. If you would like to know some overview of these organizations, please look into my other video for previous module and we discussed that briefly. But for now, just remember what we are focusing on is the physical layer which is just below the data link layer and that is the layer responsible for like cabling and structured cabling etc etc so what are the physical layer components physical layer standards address three functional areas the physical components such as cabling and NICs like the network interface card encoding and how the encoding works in order to transmit that data and signaling.
So during the transmission of that data, how we're going to use the signaling. The physical components are the hardware devices, media, and other connectors that transmit the signal that represent the bits. Hardware components such as NICs, network interface cards, you know, for example, cabling materials, cable design, specifications and standards, etc, etc. I will post another video on and a series of videos not just one video on the networking standards on with respect to cabling called structured cabling but for now just remember for physical layer we are we are looking at the physical components of the network Encoding. Bits must be converted to physical signals for transmission across a medium.
Encoding or line encoding is a method of converting stream of data into bits such as zeros and ones so that it is a predefined code. Bits can be encoded to voltage levels for transmission over copper cable. For example...
if you have a cable and you can have the binary zeros represent with the voltage of zero while the binary ones can be plus one so what's going to happen is the because the transmitting data is zeros and ones because they are digital you can use the voltage difference between the zero and plus five to designate those uh signals so for example zero So based on how long that voltage remain at plus 5 and how long the voltage remain at 0 will define the bits of 0s and 1s. The bits can be encoded to optical light levels for transmission over fiber optic cable. In other words, for example, instead of using 0s and 1s, plus fives of voltage we can use light and the intensity of lights.
So for in fiber optic cables what's going to happen is the binary values so binary sorry binary zeros can be represented with a dim light while the binary ones can be represented with a bright light. To give you an idea how that works Think about it as like instead of having a voltage which is zero and plus five you're gonna have that zero represented with a dim light or no light and then plus five represented with a very bright light. So technically that's not exactly how fiber optic cables work there are more complexities going into it but for this course just remember that just like the voltage we can also use the light. Let's look at some signaling a little bit more into how signaling works. The signaling method is how the bit values 1 and 0 are represented on the physical medium.
The method of signaling will vary based on the type of medium being used. An example of this would be the fiber optic cables of optical fiber cables will use light pulses where when the pulse changes that will actually give you the idea of whether it's a zero or a one while the electrical signal over copper cable look like this and that also can give you the zero values and the plus values based on the voltage difference while the microwave signal over wireless would be uh represented on the right hand side right here would do the similar thing So basically a digital signal in what you need to remember is just zeros and ones and the voltage gonna have the sine waves and then using those voltage and digital signal we can transmit information across a medium. You may have heard about the term bandwidth especially when you are applying for ISP packages. when you get your internet connections.
So it is a common term that being used for market internet as well as some other packages, whether it's a ISP for internet for your home or whether you're for your cell phones. So what is bandwidth? It's a common term that we use, but a lot of people don't understand what it is. So let's look at what it is.
So bandwidth is a capacity at which the medium can carry data. Digital bandwidth measures the amount of data that can flow from one place to another given a amount of time. So in a given period of time. So in other words, it's not the bandwidth doesn't mean like you know how much you transfer data over a year but how much data can be transferred typically within a couple of seconds or a minute for example.
So another way to look at this is how many bits can be transmitted in a second. Physical media properties, current technologies, and the laws of physics play a major role in determining availability of bandwidth. So, on the table below, right here on the bottom, shows some examples like the units that we use for measuring bandwidth.
So BPS is the bits per second. So one bit is the fundamental unit of bandwidth and one bit is defined based on that definition. And kilobits per second is one kilobyte equal to 1000. bits per second which is 10 to the 3 and megabytes which are mbps which is one megabyte is 1000 megabyte bits per second and gigabytes which are one gigabytes equal to one you know 10 to the 9 bits and terabytes which has tbps which is terabyte per second and that's how you measure that in modern world especially in Canada you will probably gonna hear about megabytes and gigabytes when you come to the point data transmission through ISPs to your home. ISPs stand for Internet Service Providers.
This includes Show Cable, Telus, Rogers, Bell in Canada for example. They would be advertising megabytes per second and most likely gigabytes per second. What you need to remember on this slide for your exams is that these abbreviations and which one is bigger than the other one because they usually show up on your cisco exams one of the most common mistakes that people do uh instead of putting capital g here they put like simple g and capital m instead of capital m you will have simple m and that might show up on your exam and make sure you don't pick that wrong option and get that question wrong so make sure that the demand got by per second gonna be M capital BPS gonna be simple because bits per second is BPS which is all simple. So remember that that's very important. Another important concepts that you need should understand is a latency throughput as well as the good put latency and throughput is some of the common terms that you may have heard if you are a gamer for example good put is not something that very commonly heard in the you know in the general society but you need to understand all of these three concepts for your exams.
So what is latency? So the latency is the amount of time including delays for data to travel from one given point to another. Make sure you remember that definition. The latency is the amount of time including delays for data to travel from one given point to another.
In an inter-network or a network within multiple segments, throughput cannot be faster than the slowest link in the path from source to destination. Even if all or most of the segments have high bandwidth, it will only take one segment in the path with low throughput to create a bottleneck in the throughput of the entire network. So what that means is basically if you have fiber optic cables everywhere, but one segment of your data system have cat5 cable, when you transmit data through the network from one end to the other, the entire network latency will be defined by the slowest part of that network, which would be those cat5 cable link part.
So it doesn't matter you have 5 optics on either end, the middle part is cat5, therefore that will be the bottleneck for the entire network and that will define how the latency works for that network. Throughput is the measure of transfer of bits across the media over a given period of time. For your exams, again, these red tags you better understand how it works so throughput is the measure of transfer of bits across the media over a given period of time so the so the definition is very important here so due to number of factors through a throughput usually does not match the specified bandwidth in a physical layer implementation throughput is usually lower than the bandwidth There are many factors that influence throughput, such as the amount of traffic at a given period of time, the type of traffic, such as voice versus data, the latency created by the number of network devices encountered between the source and destination. So more devices connected to a network is slower the throughput going to be for that one particular device that trying to communicate to the across the other part and that will impact the other devices as well.
The next one is the good put. The good put is the measure of usable data transfer over a given period of time. Again, Make sure you remember this definition, the good put is the measure of usable data transfer over a given period of time.
Good put can be put into an equation as throughput minus the traffic overhead. So the good put is the throughput minus the traffic overhead. The traffic overhead includes the establishing sessions, acknowledgement, encapsulation and retransmitted bits. We will look into little bit of depth of you know what traffic overhead is as we go through this course but for now for your exams and quizzes remember good put is the throughput minus traffic overhead this slide is a very important slide for your ccna exams and quizzes and what i have turned this you know put it in red is very important for your quizzes so if i were you i would come back to this slide and this part of the um video and then just look into this and read it over before your exams and quizzes. Let's look at the copper cabling.
So what are the characteristics of copper cabling? Copper cabling is the most common type of cabling used in networks today. It is inexpensive, easy to install and low resistance to electrical current flow. In fact, if you look around in your home, most of your cables like CAT 6 and CAT 5, actually not most, all of your cables are made out of copper cabling.
The limitations are signal attenuation, the longer the electrical signals have to travel, the weaker they get. If you'd like to learn more about signal attenuation, I will leave a link in the description. I have done some research into signal attenuation for geophysics for my previous degree and I will leave some information about signal attenuation process that you can read into. However, those advanced concepts will not show up on CCNA exams for you guys if you are studying this particular course.
The electrical signal is susceptible to interference from two sources. which can distort and corrupt signal data. Those sources are the EMI and RFI.
The EMI is the electromagnetic interference and the RFI is radio frequency interference. And also the crosstalk. The electromagnetic interference or frequency interference, in this particular slide C squared is helpful to put it into one.
The signal of the EMI and RFI can distort and corrupt the data signals being carried by copper media. Potential sources of EMI and RFI include radio waves and electromagnetic devices such as fluorescent lights or electric motors and another example would be like a microwave ovens is another example of that. Cross talk is a disturbance caused by the electric and magnetic fields of a signal on one wire to the signal in an adjacent wire. In Telephone circuits, cross talk can result in hearing part of another voice conversation from an adjacent circuit. That's where the term crosstalk actually first used by AT&T laboratories and other people because you can literally can hear the conversation going on the other cable by the cable you are logged into.
Specifically when an electrical current flow through a wire, it creates a small circular magnetic field around the wire which can pick up by the adjacent wire. So that's what you need to remember for crosstalk. So remember the electrical signals are susceptible to interference by EMI and RFI.
and also it is susceptible to interference by surrounding wires and cables that are transmitting similar data or other data that you are the wire that you are been using that is sitting right next to the or those other wires those are called crosstalk so those are the two key points that you should get from this slide so let's look at what are the some of the things that you can do to mitigate those issues One of them is strict adherence to cable's length limits to remove or reduce the signal attenuation. For example CAT5, CAT6 cables have a limit of length and if you go little over that limit you will either get drop packets or very unstable network connections. uh some kinds of copper cable mitigate emi and rfi by using metallic shielding and grounding and some kind of copper cable mitigate crosstalk by twisting opposite circuit pairs uh wires together so you know that's okay you will see those things especially in cat6 cables for example types of copper cabling so for example unshielded twisted pair or utp cables look like this and then the shielded twisted power or STP cables will have that metal you know shield and a plastic core in the middle. This is usually you see in cat6 cables as well this is like cat5 or loba most likely and then the coaxial cables will have that shielding as you can see right here with the cable the copper wire in the center with the shielding around and then their outer copper The unshielded twisted pair or UTP.
UTP is the most common networking media. UTP gets terminated with RJ45 connectors. It interconnects host with intermediator network devices.
The key characteristic of a UTP is the outer jacket protects the copper wires from physical damage. which is that one this this part this is number one and then the twisted pair protects the signal from interference so see this uh the orange wire and the orange white wire is mixed together and then the green wire and the green white wire mixed together and then the the blue wire and the blue white wire get mixed together etc and that what what we call the twisted pairs because they are pairs and the color-coded plastic insulation electrically isolate the wires from each other and identify each pair which is that that color that you see here most of you have seen these at home and at work when you are using those rj45 jacks to connect to the internet or your internal networks so this is what the utp cable look like the shielded twisted pair or stp is very similar but it product provide better noise protection than the utp however it's a little bit more expensive than the utp harder to install than utp and terminated with the same rj45 connectors and it also provides the interconnections between the host and intermediary devices and the characteristic of a stp as opposed to the utp is that it has the outer same or similar or same outer jacket that protects the copper wires from physical damage but now you have that braided or foil shield which provide the emi and or rfi protection which is this part the foil shield for each pair of wires provide the rmi efi protection as well so that's this part this this gray one part and the color plastic insulation electrically isolate the wire from each other and identify each pair just like the utp they are a little bit more expensive and just like it's mentioned here it's a little bit harder to install but it's not that hard and but however it provides the better protection for emi rfi and crosstalk the coaxial cable it consists of the outer jacket to prevent minor physical damage A woven copper braided metal or foil act as the second wire in the circuit and also act like a shield for the inner connectors so that this braided wire or it or not only provide another you know connection path in addition to the the center core. but it also act like a shield. A layer of flexible plastic insulation will isolate this section, number two section from the inner core right here and a copper conductor is used to transmit the electronic signal will be in the center. There are different types of connectors used with coax cable commonly used in the following situations.
Wireless insulations for example, attach an antenna to a wireless device and the cable internet installations into the customer site. For example, these cables may be used by companies like Show Cable and the other one would be the Telas or other internet companies to get the connection from their centers to your house. However, I have also seen and have done coaxial cable internet within the homes internally for internal network and I will talk about that in a later video.
Just for now what you need to remember is that they were used typically for wireless installation and cable internet installations. UTP cabling The properties of UTP cabling can be described in a way that for this, you know, related to this course in this slide, but I also added an extra slide next to describe a little bit in depth so you can have a better idea, like you have a little bit of more information than what the Cisco has provided to you. So the UTP has four pairs of color.
coated copper wires twisted together and encased in a flexible plastic cover. No shielding is used and the UTP relies on the following properties to limit crosstalk. One of them is the cancellation. So each wire just like previously we looked at is twisted paired and uses opposite polarity. one wire is negative and the other wire is positive.
So they are twisted together cancelling the magnetic field that may be created by EMI or RFI. It also cancels the magnetic field that may be created by themselves because one is negative and the one is positive. The variation in twist per foot in each wire can be used uh to prevent cross stock among the wires in the cable so for example this wire is twisted more as you can see there are more turns as it you know as you go to go across the wire then this wire it has less turns so that what it doing is it's variation in the twisting per foot is preventing that cross stock from happening within the pairs This is the additional slide that we added. So the copper twisted pair cable category defines a construction of the cable which directly impact bit rate. The speed parameters shown here are the four sorry here are the sorry the speed parameters shown here are just for ethernet.
which has a distance limit of just 100 meters. So if you put more than 100 meters and you are communicating ethernet the internet it may sometimes have instabilities or just drop the connection altogether. So cat 3 10 megabyte per second typically now only found on all telephone system.
Cat 5 is 100 megabyte per second which are fast internet and also can be used for telecommunication systems as well. CAT 5e and CAT 6 1gbps and CAT 6a is 10gbps and CAT 7 which is actually not yet widely adapted or standardized per say provide upto 40gbps. What you need to remember for this class is the CAT 3, CAT 5, CAT 5e and CAT 6a. CAT 7 may show up on exams but not a lot.
So this is just an additional slide we added just to give you an idea about the twisted pair cable categories. UTP cabling standards and connectors. Standard for UTP are established by ITA, EIA. Those standards are typically labeled as TIA-EIA-568 standardization for example. And they have elements such as cable types, cable lengths, connectors, cable termination and testing methods.
You don't need to remember the specific standards for this course, but you will have to remember those specific standards for structured cabling courses that we will be going over in the future. The electrical standards for copper cabling are established by IEEE, which rates cable according to its performance. For example, category 6, category 5, category 5e, category 6 and category 7. which is in kind of in development and not widely adapted as of 2022 but you probably heard a lot about this cat type when you are buying cables as a consumer but not so much these these types like i tia eia 568 but you need to remember for this course there are these different standards that we use in our networking engineering environments so utp cabling standard uh include uh the endpoints that we actually use the connectors for and the connectors are used usually for like the cables that we use for internet rj45 connectors and they look like this and most of you are familiar with them especially in the 2022 you have seen this cable around and you have used it at work and school and etc and the termination is very important in terms of maintaining those data rates and those standards. For example, if a poorly terminated UTP cable look like this, it may not provide those standard capabilities defined by those organizations because it's poorly done. But if you've done it properly, like right here, where the jackets get pinched down and all the cables are properly inserted into the pins, it will provide those data rates described by those standards.
Again, in this course, we will not go into depth of structured cabling. I will post a different set of slides and lectures on structured cabling on my YouTube channel later this year. So in UDP cabling, there are a couple of types that you should know. for this class for cisco introduction to networks. we will actually examine this on our packet tracer labs that we will be doing soon which we will post on our youtube channel.
so the two types is the straight through and crossover. the different situation may require utp cable to be wired according to different wiring conventions. this means that individual wires in the cable have to be connected in a different order to different sets of pins in RJ45 connectors. The following are the main types that obtain by using specific wiring convention, Ethernet Straight Through and Ethernet Crossover.
The Ethernet Straight Through is the most common type of networking cable. It is commonly used to interconnect a host such as a computer to a switch. and switch to a router.
So we consider straight through cables as connecting unlike devices because devices themselves gonna do their thing to you know make sure the data is transferred properly. So remember this is a very important concept. Straight through cables are used to connect unlike devices such as a computer to a switch or and a switch to a router. The ethernet crossover cables are cables used to interconnect similar devices, for example to connect switch to a switch or a host to a host such as peer to peer network or router to router.
However, crossover cables are now considered legacy as network interface cards use medium dependent interface crossover or auto mdix to automatically detect the cable type and make the internal connections. So remember that, in the old days we used straight through and crossover cables and you cannot mix them up because the network interface cards on similar devices cannot differentiate from unlike devices. But now in modern day, if you use a straight through cable to connect similar devices or unlike devices, the network interface card can use auto mdix to determine what type of cable it is and make the connection work.
However, for this course, you should remember for your exams that the straight through cables are used to connect unlike devices such as host like a computer to a switch and switch to a router while the crossover cable use similar devices on either end to connect to each other such as switch to a switch or router to a router that is important to this course but in modern day in 2022 we almost always use straight through cables no matter what device we use because the network interface card have built in auto mdix Another type of cable is Rollover Cable which is a Cisco proprietary and it is used to connect a workstation to a router or a switch console port. Straight through and crossover UTP cables are defined by T 568A and T568B wiring standards. On the top you will see those wiring standard T568A and T568B. In Canada we use either type of termination but in modern times if the cables are done recently most likely all of them are done on T568B standards.
So the cable type For example, on this bottom table shows that Ethernet straight through and the both end can have either T568A or T568B. But you need to make sure you pick either or on the both ends. You can have one end T568A and the other end T568B. If you are using T568B on one end, you have to use the same on the other end.
And typically it's used to host to network device. Ethernet crossover is one end gonna be T5-568A and the other end has to be 568B. So that's what make it a crossover because one end is 568A the other end gonna be 568B.
Otherwise it's just gonna be a straight through and it is used to host to host, switch to switch or router to router. And remember Ethernet crossover cables are legacy due to the most nicks nowadays have the auto mdix as i mentioned in the previous slide and most of the cables that you're gonna make modern day and use gonna be the just the internet straight through cables which you have either type when i'm doing cabling i typically use t5 cc8b on both ends just because that's the most common standard used by nasa and bunch of other major organizations but you can use either one just need to make sure you use the same on either end Again the rollover cable is a Cisco proprietary. We hardly use them and they are used for host serial port to router or switch console using a special adapter.
However if you are a network engineer or a network technician working in the industrial environment you may come across a lot of network rollover cables because we use a lot of Cisco devices. Let's look at Fiber optic cabling. Some people call this optical fiber cabling. Especially in Asia.
I know Asian engineers in South Asia and East Asia use optical fiber cabling. But in North America we usually call it fiber optic cabling. So let's look at fiber optic cabling briefly.
So what are the properties of fiber optic cabling? Not as common as UTP because of the expensive nature of these cables. They are a little bit more expensive and they are also very fragile compared to let's say copper cabling. Ideal for some networking scenarios such as connecting data center to a data center or you need very high bandwidth and throughput between your machine and your for example network connected file storage device.
where you have like, for example, If you are making 4K YouTube videos and you are storing them on a server, even locally, you can have the direct fiber optic connection so that you can transfer between your server and your computer for video editing purposes. That's an ideal home use of fiber optic cable, for example. One of the key advantages of fiber optic cable is it can transmit data over very long distances.
at a very high bandwidth than any other networking media made of flexible extremely thin strands of pure glass uses laser or led to encode bits as pulses of light and the light is not affected by electrical noises so the electrical interference will not impact your fiber optic signals It is less susceptible to attenuation, hence you can send it in long distance and completely immune to EMI and RFI as I mentioned before. Fibre optic cables act as a wave guide to transmit light between the two ends with minimum signal loss. So we are not saying there are no signal loss but it has extremely low signal loss. In fact it is very negligible. So what are the types of fiber media?
One of the most common types called the single mode fiber. The other common type is called multi-mode fiber. The single mode fiber is very you know characterized by a very small core. This diagram is a very good diagram.
to you know just look at to understand what single mode fiber look like and it uses expensive lasers to come you know transmit the data and it can have long distance applications uh connecting on either end and the range is around 100 kilometers uh to you know 100 kilometer like at one terabyte per second that's the range The multimode fiber has a larger core so the thickness of this core is bigger here. This diagram doesn't actually show that thickness difference clearly but it is a little bit thicker and uses less expensive LEDs and LEDs transmit at a different angle like this instead of sending just a one single light you know path it's gonna have multiple light paths. and it's a service typically a shorter range like a 550 meters as opposed to 100 kilometers.
It provides a gigabyte per second connection speed and compared to a single mode fiber it is a lower cost. I would expect the single mode fibers to remain on like connecting major data centers for as opposed to multimode fiber is currently being adapted in buildings like for ethernet connections as well for like i said transmitting like a 4k video across a server in the basement while you're on the ninth floor for example because it's cheaper but it still provides that faster speed than a utp cable the dispersion refers to the spreading out of the light pulses over time so it is like you know signal degeneration type of thing but it's just you know refer to the fiber optics it increased the increased dispersion means increased loss of signal strength so mmf has greater dispersion than smf with the maximum cable distance of mmf is 550 meters so multimode fiber or mmf has just 550 due to the dispersion rate is being higher as opposed to smf the single mod fiber have a 100 kilometer long range because it has a less dispersion rate so as i mentioned before the fiber media doesn't have a perfect you know signal transmission but it is much much better than using uh you know copper cables You know copper cable couldn't sustain that kind of a data rate at a hundred kilometer for example the distance so fiber optic cabling usage Fiber optic cabling is now being used in four types of industries. As I mentioned, it's being used even in home use nowadays actually, like internal networks in large companies.
Enterprise networks, for example, used for backbone cabling applications and interconnecting infrastructure devices, such as servers that require very high throughput and bandwidth to the end devices or the intermediary devices. Fiber to the home or FTTH. used to provide always on broadband services to homes and small businesses such as in Canada like Show Cable Fiber, Telus Fiber to Home, Rogers and Bell also have their own networks to Fiber to Home.
Long-haul networks used by service providers to connect countries and cities as well as their data centers. For example in On, I think Vancouver, they have multiple data centers owned by Microsoft Corporation in Canada, and they use those fiber connections to connect those data centers together, even though they are in the same city. Submarine cables. So, submarine networks used to provide reliable, high-speed, high-capacity solution for surviving harsh undersea environments. And, you know, It provides a trans-oceanic connection such as connecting Japan to rest of Asia for example, and or Japan to rest for the United States.
They have done those fiber cabling even in 1980s. My dad used to work on fiber optic networks with Japanese companies in the 1980s for example, making sure those cables are connected properly and etc. So our focus in this course is the use of fiber within the enterprise environment. So that is important because that might show up on exams but you still should remember these four categories of fiber optics used in modern day network engineering environments. So let's look at the fiber optic connectors.
Straight tip or ST connectors look like this. Lucent connector or lc connector is a simplest connectors and they look like that and then we have the duplex multi-mode lc connectors that you know similar to that and we have subscriber connectors sc connectors see it looks like this i know a lot of students forget this slide when they go to the but this shows up on your quizzes and even final exam for this course please please please remember what they look like and what they call so if they give you an image of this an image of that and you have multiple choice uh selections where you had to pick what this looked like you should be able to separate the straight tip from the subscriber connector so you should be able to separate from st and sc and identify them on an exam or a quiz that is very important so you can come back to this slide and look at them and the next slide we're going to look at those cables they also do show up on cisco exams a lot of people forget that as well so let's look at that so these are like the cables the patch codes so this is the sc sc type and this is lclc type this is else stl c type and sd sc type big could give you these images and ask you what these types are and you should be able to pick up those from the multiple choice. Typically a yellow jacket is for a single mode fiber cables, an orange jacket or aqua jacket for multi-mode fiber cables. These also do show up on exams. So for this course remember these different types of cables and these different types of connectors because they do show up on exams.
Next, we're going to look at fiber versus copper. Typically, like looking at like kind of advantages and disadvantages. Optical fiber is primarily used as backbone cabling for high traffic, point-to-point connections between data distribution facilities such as data centers and for the interconnection of buildings in multi-building campuses, such as if you have a university campus environment.
Or my example of Microsoft having multiple data centers in Vancouver and connecting them together. So implementation issues and UTP cabling and fiber optic cabling and we're going to look at them separately. You don't need to memorize this table but you should have a very good idea about the separation like what are the differences between UTP cabling and fiber optic cabling. You should actually memorize the bandwidth differences because that's a key difference between the two cable types.
So bandwidth supported on UTP is 10MBps to 10GBps while the fiber optic provides 10MBps all the way to 100GBps. Distance is limited with UTP up to like about 100 meters maximum and if you even have a cable exactly 100 meters that might create like issues with packet losses. While fiber optics can provide very long cable connections without having an end device in the middle.
from 1 meter all the way to 100,000 meters. UDP cabling is not very immune to our EMI and RFI interference while the fiber optic cabling is extremely immune and in fact it is completely immune to EMI and RFI so if you have a microwave antenna or satellite dish systems nearby that will not impact your fiber optic cable at all but if you have a utp cable you might have data packet loss issues or crosstalks because of emi and rfi immune to electrical hazards the cable a utp cabling because they are using copper wires they are not immune to electrical interference and hazards but however fiber optic because they use light and glass fibers it is completely immune from electrical hazards Media and connector cost. UTP cable are extremely cheap. They are used in homes and small offices and businesses as well as in large businesses.
Fiber optic cables are extremely expensive. In terms of installation, it is very easy to install UTP cable while the fiber optic cables are a little bit more complex. UTP cable, you don't have to worry much about, you know, the safety even though you still do. you know just less likely you're going to get hurt by working with all utp cables fiber optic cables you have to be careful with using those cables because of you're using light to transmit that data you had to take more precautions especially don't look inside the you know fiber optic cable because you might get blindness it may look like it's not transmitting anything but if you are not sure what's on the other end never directly look at the fiber optic cable even if it is disconnected actually because there's no need to look at it. In addition, if you take the structured cabling classes, you will realize that there are safety precautions, more safety precautions that you need to take with fiber optics because of those glass fibers can get underneath your skin and that can create a safety and health issue when you're working with them.
But you don't have to worry that much about with the UTP cabling. for now for this course because this is not a structured cabling course only thing you need to remember is just the differences between those two but remember the bandwidth difference that is very important and the distance difference more than anything else that you need to take out of this slide finally we're going to look at the wireless media so what are the properties of wireless media it carries electromagnetic signals representing binary digits using radio or microwave frequencies and the signals pass through the air as opposed to pass through a wire such as fiber optics or utp cables this provides the greatest mobility option wireless connection numbers continue to increase as we work with cell phones and laptops all over the world cell phones are getting cheaper laptops are getting cheaper and it makes it easier for a lot of people to connect to a network. Some of the limitations of wireless is the coverage area.
The effective coverage can be significantly impacted by physical characteristics of deployment location. For example, in certain countries such as in South Asia and Asia, most of the buildings are made of concrete walls. the separation between different rooms are made out of concrete so the coverage area will have a greater impact there compared to when you are using in wireless access points as opposed to let's say you are using on the same type of access point in places like Canada where we use mostly wood as our main construction material.
Interference. The wireless is susceptible to interference and can be disrupted by many common devices such as microwave ovens for example or other antennas and other devices such as home automation devices like ZigBee and Z-Wave may interfere sometimes with certain wireless devices. Security.
The wireless communication coverage require no access to a physical strand of media so anyone can gain access to a transmission. So if you have a UTP cable and fiber optics only network it is going to be like pretty hard for someone to access your network data because you don't have any wireless points where they can access it without having that. physical connection to the network but with having a wireless option it open up a security backdoor to certain people who may be able to hack into your system easily than whether they you know then just physically accessing it and pulling a UTP or fiber optic optical fiber cable. Shared medium so WLAN operates in half duplex which means only one device can send or receive at a time. Many users accessing the WLANs simultaneously result in reduced bandwidth for each user.
The idea of half-duplex is very important. What half-duplex means for this class, what you need to remember is that your end device is going to communicate to the wireless access point and it waits for wireless access point to come back to you. so it's not constantly sending packets while receiving packets it's it's half duplex which means there are only one device can send that and receive at one time so no matter how fast the wireless connection is right now as of 2022 it's always going to be half duplex so your device can send the packet and wait for a few micro millisecond and then receive the packet back from the intermediary device such as a switch uh access point and a router.
So that means it's going to be slower than a for example fiber or a UTP cable. And wireless transmit microwave signals as waves and it use modulation as the process when one wave modifying the other wave. In this particular course we will not look at the in-depth technical side of things with half duplex systems as well as the modulations. I will cover that on a wireless Cisco modules that I will be posting in the future.
But for now, you just need to remember that, you know, while WLAN is half duplex and it uses modulation and prone to interference and have coverage issues and security issues. The IEEE and telecommunications industry standards of wireless data communications cover both data link and physical link layers. In each of these standards, physical layer specifications dictate the data to radio signal encoding methods, so that manufacturers such as Cisco can create a wireless access point, but your D-Link or Intel wireless network card can still access that.
wireless access point made by Cisco because they are using that the same standards. Frequency and power of transmission, signal reception and decoding requirements, again the Cisco device can communicate with a you know wireless card you have on your desktop which may be made by Intel. Antenna design and construction the same thing.
So you need to remember the remember these for your exam. The IEEE standard for wireless media we cover data to radio signal encoding methods, frequency and power of transmission, signal reception and decoding requirements, and antenna design and construction. Modern wireless standards include Wi-Fi which is IEEE 802.11 which is the wireless LAN WLAN technology.
The Bluetooth technologies IEEE 802.15 which is the wireless personal area network WPAN standard. WPAN is another term for Bluetooth. WiMAX which is the IEEE 802.16 use a point-to-point multi-point topology to provide broadband wireless access. They sometimes used by your ISP to connect their two buildings may be used by WiMAX or campuses.
SIGBEE another IEEE 802.154 another IEEE standard which is a low data rate low power consumption communication typically used for IoT devices such as as I mentioned the home automation can devices can be used can be used by maybe use utilizing the SIGBEE standards. And what you need to remember there are multiple standards for wireless and they are defined by the IEEE standards used by Cisco and multiple other vendors. In general, a wireless LAN or WLAN require the following devices. The wireless access point which I mentioned before also known as an AP which concentrates wireless signal from users and connect to the existing copper based network infrastructure. So your router your home wireless router is built in have a built-in AP so that's why they are all together but in an enterprise environment typically your router is separate from your access point where you connect a RJ45 connector and a UTP cable to connect a wireless access point on the other end of that cable and you can hook up that wireless access point or install that wireless access point on a ceiling for example where users will receive that wireless signal as opposed to your home router which has a router and access point built into one where you have antenna sticking out from your router which provide both routing capabilities as well as a wireless access point capability so that's why you don't see the access point in a home environment Because to make it easier for use for end users and consumers manufacturers such as Cisco and D-Link And other companies have provided you with the device access point and router all together But in an enterprise environment or business environment, you're gonna see these wireless access points Are placed on ceilings or walls which provide the concentration of wireless signals from users and then connect it to a network infrastructure using the RJ45 connections.
The other one is the wireless network interface card adapters or wireless NIC adapters which provide the wireless communications capabilities to network host. So that could be an end device. For example, you can have the NIC card with the for example Intel network interface card with the wireless capabilities.
We will provide the connection between your device and that access point. There are a number of WLAN standards. When purchasing a WLAN equipment, ensure that the compatibility and the interoperability. So, even though IEEE have those standards built in, you need to make sure that if you're buying a wireless access point that is working on WiMAX, it will not work on Wi-Fi, for example. So, this is an enterprise use and this is maybe like you know other end user use.
so you need to make sure that you are using the interoperability and there are also different wireless standards such as bgn so it is still wi-fi standards but there are different categories of like bgn so you need to make sure your wireless access point is capable of communicating in those standards so if you have older laptop for example with only running on bg but your wireless access point is only transmitted in n standard it cannot be connected to each other. Network administrators must develop and apply security policies and processes to protect WLANs from unauthorized access and damage because this is probably the most weakest point or weakest link in terms of security for your network, the WLAN networks. There is a packet tracer activity. available to you if you are registered with this cisco netacad ccna course introduction to networks you can go ahead and download that packet tracer file and check the these you know options that you can play with. I will try to make that lab on my YouTube channel and post it onto my YouTube and I will leave a link below in the description once I do that.
But for now, if you have access to this course, just access that through your course material and you should be able to do those packet tracer activities. I would highly recommend that you go through those packet tracer activities before your quiz or exam because that will give you a better idea of everything that you learn in this module. And there is also a lab available on your Cisco Netacad. Again, I will try to leave a link either through Cisco modules available to me or by working through the lab and going through them and posting as a YouTube video. But if you have access to it, just go ahead and do those labs and you will learn these concepts.
So what did we learn in this module? So this is a brief summary for your module practice quiz as well as your final quiz. So we learn before any network communication can occur a physical connection to a local network either wired or wireless must be established.
The physical layer consists of electronic circuitry, media and connectors developed by engineers. The physical layer standards address three functional areas. physical components, encoding and signaling.
It is very important that you remember that for your exams. And three types of copper cabling are UTP, STB and coaxial cable or coax. UTP cabling conforms to the standards established jointly by TIA and EIA. The electrical characteristics of copper cabling are defined by Institute of Electrical and Electronics Engineers.
The main cable types that are obtained by using specific wiring conventions are Ethernet straight through and Ethernet crossover. Optical fiber cable transmit data over longer distances at a higher bandwidth than any other network media. distinction between the optical fiber or fiber optics and the copper cabling. There are four types of fiber optic connectors ST, SC, LC and duplex multi-mode LC.
Remember you not only need to know what they are you also need to know how to identify them if somebody given you a picture of their connectors or cables. Fiber optic patch codes include SC, SC, multi-mode, LC-LC single mode, ST-LC multi mode and SC-ST single mode. Again, you need to be able to identify them if somebody give you a picture and ask you or your instructor give you a picture and ask you to identify them or actual cable and ask you to identify them.
Wireless media carry electromagnetic signals that represent a binary signal binary digits of data communications. using radio or microwave frequencies. Wireless does have some limitations, include coverage area, interference, security and problems that occur with any shared medium.
Wireless does not have the security associated with cables but it still provides very good flexibility and it is a growing area where with wireless devices such as cell phones and laptops becoming more and more common use in modern day. Wireless standards includes Wi-Fi standard, Bluetooth standard, WiMAX standard and ZigBee. Wireless LAN or WLAN require wireless access point or AP and wireless network interface card adapters on the end devices in order for them to connect to that AP.
So remember those things because those do show up on the exam. Finally, we're going to quickly go over new terms and commands that we cover in this module. And it's just a single slide.
So remember these options that we discussed. They are already in the summary as well as everything that we covered today. So I'm not going to go over it. But if you want to pause this video on this slide and quickly go over to just to recap what we have learned. And you can go to this place on the video.
now you have an idea about all the basic concepts and commands that we just learned And that's everything for today and that's the end of this module. In the future we will be posting a little bit more information about the concepts that we covered in this module as well as the future modules. So make sure to subscribe to my channel and thumbs up and until next time have a nice day and good luck with your exams.