hello friends welcome back to the class of fundamentals of information technology after this lecture you will be able to understand about the computer networks and the uses of the computer networks you will be able to explore uh different kind of characteristics that uh formulate an important features of a computer of a computer network then you will be able to learn different types of networks that are existing across the world uh first of all you must be thinking or wondering about what actually is a network a network is actually a set of large number of devices that are often referred to as nodes that are connected to one another via some communication links a node it can be a computer system it can be any printer it can be any other device that is capable of sending or receiving uh or generating any kind of data uh sending the scene the data that is generated by other nodes on a particular network a link if i talk about a link we say that nodes are connected via communication links so those links can be any cables it can be any uh it can be air it can be optical fibers or any other medium uh that can involve a transporting of signal from one source to another so if i talk about the network criteria they can be different criterias for establishing a particular network uh like performance for judging a particular network we can say performance is there performance it basically depends upon the performance of the different elements of a particular network that we call as the network elements uh it can be measured in terms of delay it can be measured in terms of throughput then we have reliability how much reliable a network is that basically indicates the failure rate of a network component so whether the components in a particular network they fail out in case a failure to one particular device or one particular equipment is taking place and it is also hampering the working of the other equipments then in that scenario we say that the network is not very reliable so this is actually mirrored in terms of availability and robustness of a particular network the next network criteria is security how much secure a particular network is this data protection against uh corruption of any files loss of any data uh that particularly pertains to the security of a particular network how many malicious users are there whether they are detected whether they are able to exploit the particular network whether they are able to exploit the machines on a particular network that will actually hamper the security of a particular network and that will indicate that this network is not very secure then next is network criteria type of connection whether it is a point-to-point network that is where a single transmitter is there and single receiver is there or whether it is a multi-point network so in case we talk about a multi-point network uh multiple recipients of a particular single transmission are there then topology of a particular network what is the topology of a particular network then it depends upon the type of transmission of a particular network whether it is a unicast network whether it is a multicast network whether it is a broadcast network now what is the difference between all of these unicast multicast and broadcast when i talk about unicast it is one to one transmission from one point in the network to another point that is one sender is there one receiver is there each having a unique network address then comparatively uh multicast uh it involves sending the data across the computer network to several different users that are also operating on the same at the same time then broadcasting broadcasting is transmitting a particular program or information with the help of radio or television the next is after the networks were discussion about what is a network what is the criteria for identifying a particular network whether it is performing well whether it is reliable or not how much secure a network is uh we can judge out the kind of type of connection in a network is what kind of topology is using a network next comes what is a computer network so basically a computer network is simply referred to as a collection of large number of computers and devices that are interconnected to one another via some communication channels so this can as well as facilitate a kind of communication uh that computers can be sharing the resources or any information among each other and they are interconnected among each other so there are different characteristic features of a computer network a network can be classified according to different kind of characteristics whether uh as already indicated performance reliability energy efficiency capability security relia scalability of a network how much fair network is whether all users are getting fair deal of resources that is how fair it is then adaptable then channel utilization and throughput how what is the response time of a particular network how much well the utilization of a network is going on how much adaptable a particular network is so these are the different kind of characteristics of a particular computer network now let us explore each of these characteristic features one by one indeed so first and foremost is a performance so performance of a particular network it is mirrored out with the certain parameters certain matrix other some ways are there first one is a transit time now if i talk about transit time this is a time that is taken by a particular message or a particular data or information piece of a particular message to travel from one device to another device so that is the total transit time okay then response time response time is the time that is elapsed time between the inquiry and response of a particular uh particular requirement so suppose you want to send some data to one source to another okay the time taken for that data to travel from your source to a particular destination is the transit time and the time that is in case you want to send any inquiry okay so the time that has taken for your inquiry okay to be reverted back with a particular response that time is called as the response time then uh the performance of a network it also depends upon certain parameters like what is the capacity of a particular software what is what uh what is a kind of hardware that is used out for communication what is the capability efficiency of a particular hardware to how many number of users the information or a message is required to be communicated whether it is to be a single way or multi uh multiple users are required to be sent out then the type of transmission medium kind of cabling kind of wiring wireless it is so that kind of latencies or all these informations that depend or that feature the or that impact the overall performance of a particular network then a frequency reliability is the another factor that reliability indicates the frequency of a network failure okay uh the more the failure the less reliable a particular network will be so this is actually the meyer of the time taken by a particular network to recover from any failure in case if it is there it also indicates a robustness in a particular network in case of uh any disastrous activity takes place or any misfortune happening takes place so whether that network will be able to rel is reliable or not whether it is robust or not that also characteristic characterizes an important uh feature of a particular network the next kind of parameter that impacts uh or important characteristic of a network is energy efficiency these days uh global warming is consistently rising we are suffering from uh uh from a very vast climate change so energy efficiency or a green environment is something that is being emphasized upon by all the governments across the world not just the government but different societies and it is the need of the art in order to enhance the environmental sustainability uh the governments in making different kind of initiatives not just governments but in computing sector uh they are also working towards in uh towards developing a green computing strategies so basically in case of networks as well the uh the energy efficiency pertains to the amount of data energy that is consumed per unit of successful communication so every time a communication takes place or any working of a particular laptop or a computer system takes place they do definitely dissipate some amount of heat so this heat dissipation counts out to the energy consumption or energy dissipation in a particular system so that energy come consumption that is done per unit of successful communication that indicates the energy efficiency then next parameter that indicates uh important characteristic of a network is security so there can be in a computer network network security issues can be there uh data needs to be protected unauthorized users need to be restricted out from assessing any particular data in a particular network for manipulating any data protecting the data from any unauthorized access or any unauthorized user protecting the data from being manipulated from being used out from being listened out by a particular user and how that data in case it is corrupted out it is manipulated out how it can be recovered to into its original format that also formulates an important part of a network security then as fairness the ability of a particular system in order to equally share a common transmission channel that also indicates the fairness of a particular network the next is adaptability adaptability pertains to how much adaptable a particular network is whether any changes are taking place across the uh the outer environment whether that system whether that network is able to accommodate to those changes or not that also indicates the adaptability of a particular network the next kind of characteristic feature of a network is the channel utilization it refers to the bandwidth utilization for effective communication of a particular network then we have throughput now throughput is amount of data that will be successfully transferred from a particular sender to a receiver at a particular given period of time then is scalability now this indicates how much scalable a network is so this is the ability of a network to accommodate the change to accommodate more and more users into it more and more devices more and more computers into it and whether it can be if it is a wide area network it can be used to accommodate more and more networks into it so we have different kind of scalabilities we have horizontal scalability we have vertical scalability if the network is able to accommodate more horizontally that is horizontal scalability if a network is able to accommodate more and more machines more and more computers more and more devices vertically vertical rising that is called as vertical scalability of a particular network then is the contain then we have to discuss about how sharing of data can take place anywhere at any time so sharing a data over a particular network in addition to saving any kind of place marks or any folders to your local computer you can place your data into a web server or network server these days many of you are might be using google drives okay uh you all know that you can access a google drive from anywhere anywhere everywhere you are available if you have the internet connectivity you can access your data data saved out on a google drive uh for example google earth google earth is a global mapping program uh where the users who have access to the server they can then use that data or that is available on google earth as with other documents you can also create links or references to kmz files kmz files are the kind of files uh the full form is keyhole markup language zip files they are used for easy access and they are used to store the map locations that are visible through google earth instead of storing a placemaker file on the network of an or a web server we have a different advantages associated with uh with it uh storing a placemark file or a network on a web server it offers different kind of advantages first one is accessibility if you place your data if you have your data stored on a network server on a web server you can access it from anywhere any computer anywhere you are located you are moving remotely uh over uh during your transportation from one place to another you are located remotely so you can access your data from anywhere over here in case you have placed it on a particular network server on a web server so provided you have a public access to it or whether you have a login access to your particular file or a network network server then is is in distribution so if you have access to it you can distribute it openly this is actually related to developing an extensive presentation folder for google earth software you can make that a presentation available to everyone who has access to your network storage uh location or the web server so it is very convenient and sending that data to a particular person via email one thing is the storage capability is more uh in case of network or web server web network storage and it is more easily to be available and it is more easier to communicate it to more large number of people instead of some sending it personal made to some particular person then automatic updates and network link assess is also easier in case you want to store the data save the data to a network server any new information or changes you make to the network server network based kmz information it will be automatically available out to all the users who have access to that kml data why a network link that you had provided just map this to similar scenario of using the google drive then backup facility if for some reason the data on your local computer it gets corrupted then in that case you can open any kmz file that you had already saved on your network server or network location and if so desired you can fail that you can save that again to your local file system then saving data to the server how it can be done in order to make a place mark or folders available to the other people via server you can fail save that particular file to appropriate location one thing is you can save to a network server in order to save to the network server you need to follow the steps of saving places and data in the save location uh save file in a particular location of a particular company okay rather than to your local file system second is you can save the data you can make it say or save it to a web server you can save a place mark or folder to a particular web server first of all save the file to your local computer as i had already told earlier once the file is saved on your local computer you can create a separate kmz file and you can use that a similar utility or you can use ftp or similar utility in order to transfer that file to a particular web server then is opening the data from a network server in case you want to open the data from a net network server uh if you're working in an organization where placing of data data is placed out in a network uh that you have access to you can just open that data in the same way you would open a saved file kmz file on your computer system local computer system from the file menu you can select control plus or in case you are using windows or linux and in case of mac you can use uh plus oh locate the file that you want to open and open it up then next comes what are the different kind of uses of a network uh first of all i'm indicating that you can access any data if you have located in a network server so you can access it from anywhere you can save a backup copy of it uh in case some changes are made out that would be complicated propagated out to all the users across the world who whosoever has access to you that particular file or folder that you have given a link for accessing so basically creating a particular network in case of lan it helps the people into increase their efficiency because they can share the file about with one another they can share the resources and they can do many other things lan networks they have attained very much larger popularity in recent years moreover efficiency can be improved more improved communications are also available with the help of a particular network connectivity now next comes what are the different kinds of network different types of network so basically we have different types of computer networks based on the geographical scope or a particular scale so uh first of all is the lan pan area network that is personal area network second is lan that is local area network then we have man that is metropolitan area network then we have wlan that is wireless local area network that is while wlan then we have wan that is wide area network now let us explore each one of these one by one first of all we need to understand the distance this table is indicating you the distance between all these uh different networks uh when i talk about the pan the distance that it discovered is one meter that is a working table then i talk about the local area network it can be within a room it can be within a building that is single land over there or multi building land then we have it is 10 meter 100 meters the range if i talk about the metropolitan area nato network it can be connected out to a particular city in a particular state over 10 kilometers is the range it is very small then we have the wide area networks uh that can region from uh the country to country that can be connected out state to state that can connect continent to continent they can connect to planet to planet so the range of wide area networks is very high though now let us explore each one of these in detail first one is pan that is personal area network so uh this kind of network is a network that is concerned with the exchange of information within the vinci vincity of a particular person as you can see we have a wide array network you have your printer we have a camera we have a game pad we can connect different kind of devices using a phone cable we have so we can connect different kind of devices you might be using alexa these days so you are actually creating a kind of personal area network with your you might be using your uh mobile phones with the bluetooth capability to in order to transfer the data so that range is very less from one mobile to another you might be using share it so that is also a kind of personal network that you can use to communicate with one mobile to another then we have the systems in case of personal network they are wireless and they involve the transmission of data between devices such as your personal computers are there tablets computers uh smartphones are there so uh this allows either transmission of data or information between such devices or to serve the data or to a particular server as a network that allows further up linking to the internet so you can further clink out to the internet then we have local area networks so as you can analyze over here a local uh lan network it connects the network devices over a regular relatively short distance so this distance is little more as compared to the personal area network a land can be existing within a particular campus within a particular building that a single building land or it can connect out to multiple building lands okay multiple lands can be interconnected that is multiple building lands over here then uh land networks they are mostly privately owned networks okay they can operate in a very small geographical area that is 10 meters to few kilometers widely used so they can be used to connect the personal computers and workstations in offices and libraries or factories they can be used to share the hardware like printers scanners can be shared out or any application software can be shared out they can be used to exchange information among different kind of devices so next is lan networks they are a network office building school or home usually uh they consist of a single lan okay whereas if we have few smaller lands that are grouped together uh that formulate a uh multi-building land as well so land will span a group of nearby buildings as well next uh lands they are also owned controlled are there as i had mentioned they are privately owned so their own control and managed by a particular single person or it can be within a particular organization same building over here so they can be used for certain connectivity technologies are used like ethernet and token uh methodology standards are also used out for lan networks then local area networks they are distinguished from one other by three different characteristics first is the size lan size of a lan is restricted by the number of users who have license to access that operating system or application software on a lan then transmission technology lands consist of single uh type of cables and all the computers are computing uh connecting devices they are also connected out to uh to a particular lan then lands are distinguished from one another by different characteristics another one is the uh type of topology that is used for a lan okay so most uh in most of the cases the local area networks they use a 48-bit physical address in order to communicate so you can see an isolated land that is connected out 12 computers to a particular hub in a closet over here okay so next is a wireless local area networks if i talk about the lands we have further capabilities in land that is a wireless capability so a network that allows the devices to connect and communicate wirelessly that is called as a wireless lan uh it is uh not very similar to the traditional wired lan uh in case of wired lan traditional wireline we had devices that were communicating over ethernet cables uh devices on a in case of wlan they are connected via wi-fi okay uh new devices they can be easily added and they can be configured using dhcp data's dynamic host configuration protocol then in case of wlans they can communicate with other devices on the network that uh the same way they would have communicated in a wired network the main difference between the wired and the wireless lan is how the data is transmitted in case of lan the data is transmitted over uh any kind of physical uh cables it is transmitted out using different physical cables in the series of like ethernet and tokening packets they are consisting of so you can see this wireless lan over here we have different kind of devices clients uh we have the mobile phone we have the laptop we have desktop uh we have a different kind of devices routers and modems are there so through these modems they are connected out to the internet then uh wireless local air networks in case of these uh local area networks data is transmitted or with the help of air using the air one of the protocols that is used extensively in uh wlans is eight zero two point one one ieee standard uh so many wireless routers are also including ethernet ports they are providing connections for a limited number of wireless devices then next comes the metropolitan area networks i have already discussed metropolitan area networks uh they are spanning from in a particular geographic area of a particular uh i would say a particular city okay a small metropolitan city so a network spanning a physical area larger than land but smaller than a van such as a city that would be a part of this metropolitan area network it is owned and operated by a single entity such as it can be any government body or any large corporation it can be any uh service provider over here uh uh whereas if we compare this with the further thing that is the wide area network so this range of wide area networks is very large it can span more than one geographical location offer it can be uh connecting different separate lands with it so geographical uh disper it is a collection of geographically dispersed lands okay so it can span a large physical distance as compared to the lan and man so for uh example of this van is you are extensively using is the internet okay uh where a network device called as a router it connects the lands to a particular van in case we talk about the ip networking the router maintains both a lan address and also it maintains a van address so you can see the scenario of a van where one city one local area network we can say are different kind of networks over uh one in seattle then in toronto and new york they are all connected out through this van so vans are much slower than lands and they require additional and complicated hardware is involved out at complexity is very high cost is very high because it requires different kind of devices such as routers are there dedicated lease the lines are there and complicated implementation procedures are also involved in that so when we compare this vans and lands most of the vans like the internet they are not owned by any one particular organization they can be existing rather existing under collective or distributed ownership and management uh they use different kind of technologies uh such as atms asynchronous transfer mode is there frame relay and x.25 for connectivity over a larger distances longer distances is required out then comes the internet works the practice of connecting a computer network with other networks with the use of gateways okay so multiple networks can be connected with the help of the gateways that can spam different kind of networks multi different heterogeneous networks can be connected out that can be done through the help of internet works so internet works they are uh they involve a common method of routing uh information that is finding the best path okay in uh packets between the networks the resulting system of interconnected networks is called as inter network or we call it as internet as well uh so here we have many underlying hardware technologies but they are unified under one internet working protocol ip protocol and that is a standard protocol we often call it as we often repeat or we often call it i refer to it as a tcp protocol suit so you can see this over here this is a heterogeneous network that is consisting of four different vans and two lands over here so this is a kind of example of an internet or inter network that's all for now thank you so much