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Today we will see network topology. Upon the completion of this session, we will be able to understand various network topologies like bus, star, ring, mesh and hybrid. We will also understand what are the advantages and disadvantages of bus, star, ring, mesh and hybrid topologies. Firstly, we will start with what is a network topology. We have some nodes and we have to arrange these nodes so that we can

But in a closed loop, if you observe, this is a bus topology, but this is a closed loop. So here the nodes involved are paired to paired land topology nodes. It means there is no one in superior in this network and there is no one inferior in this network. All nodes are with equal rights and that is why we call these nodes are paired to paired nodes. And every node will have two connections, one to each of its nearest neighbors. And the communication is all connected to each other.

ways unidirectional. Suppose if this node wants to send some data to this node and the network is set up like the flow of data should be in this direction and this node will send this data to this node and this node will forward the data to this node, this node, this node and finally, it will be received by this node. The communication will not happen directly like this. The communication will be like this because the communication pattern of ring topology is always unidirectional and you may ask me how this communication will work.

Then token will be passed on and this token will be circulated throughout this network. It means whoever holds this token, it's their time to send their data. And this is how all nodes gets opportunity to send or receive the data. Just watch this example. The token is circulated throughout this network. It means whoever is holding this token, it's their turn to send the data. And this is what exactly a ring topology is. According to the advantages of ring topology, it has better performance than bus topology.

communication pattern. It has to send the data by crossing these many nodes and finally reach the destination. And one of the disadvantages is being unidirectional. At the same time, a single point of failure said this link is failed. So the entire network is disrupted because of this. A node failure or a link failure will definitely affect the entire network. And this is what the primary disadvantage of a ring topology. If there is very high load in the network, then the performance of

establish communication among all the nodes. Topology means arrangement of nodes of a computer network. Say I have to arrange all these nodes so that I can establish communication among all the nodes. Topology can be viewed as a layout of a computer network. Topology can be viewed as a physical topology and logical topology. Physical topology means where I am going to place all these nodes. This is what physical topology. Say I can place all these three nodes in ground.

and it is a scalable network. And start topology has a serious disadvantage too. A failure in this central node will affect the entire network. If this node that is the switch or the hub is failed, no communication can take place. At the same time, if this node is overloaded with lot of traffic and lot of processing, then the communication or the performance is affected. That is what we call a subotal network. You have to spend some money for purchasing this hub borrower.

switch. So obviously it is going to increase the cost. So there are some disadvantages. A single point failure is going to affect the whole network and there can be bottle next due to a overloaded hub or switch. At this same time you have to spend more for purchasing this hub or a switch. We can also have a variation of a start topology like this. This is one start topology. Another start topology you can connect these two start topologies with the help of a repeater. We will see about repeater.

the next lecture. Now the point to note is that two or more star topologies can be connected with each other like this. And the last topology of the session is the mesh topology. If you observe, there are five nodes. If you observe, this node is having a link to all other nodes. Likewise, this node is having link to all other nodes. So if you observe keenly, this is the topology where each node is directly connected to every other node in the data

network and thereby it provides 100% fall tolerant and reliability. Suppose if there is a link failure encountered here and this computer has another way to reach the destination. If this link is failed, this computer has so many ways to reach the destination. This is one way, this is another way and this is another way and this is another way. There are so many ways for a node to reach the destination. We will see the advantages and disadvantages.

disadvantages now. The advantages of Mischto Apology are it is fall tolerant. It means a failure is not going to affect the network. At the same time, you can relay upon this network because somehow your data will definitely reach the destination. Even if there are link failures. And coming to the disadvantages, if this is going to send a broadcast message, broadcasting means one sender all receivers. This broadcast will be forwarded to everyone in the network. Again, this guy is going to do a broadcast to everyone in the network.

network. The same broadcast which is sent by this computer and it will also be received by other computers and those computers are going to forward the same broadcast to the sender. There are some issues with the broadcasting. Since mesh topology involves a lot of links, so it is obviously an expensive one. At the same time for smaller networks this mesh topology will work fine. And it is really impractical if your network involves 1000 or 2000 computers or more than that, these are all the disadvantages of a mesh topology.

You

That is the data. Now the problem with this approach is if EA wants to send some data to B, every one will receive a copy of the data signal including B but all others will deny or reject this packet. Why because this data signal is intended to the recipient B and not to anyone else in the network? So now we will see what is a bus topology as per the definition. All data transmitted between nodes in the network is transmitted over this common transmission medium. So now we will see what is a bus topology as per the definition. So now we will see what is a bus topology as per the definition.

the common transmission medium and all nodes will receive the signals simultaneously. This transmission medium is capable of sending as well as receiving the data. So the data flow in this transmission medium is by direction. It means data can flow in both directions. We will see the advantages and disadvantages of bus topology. Since there is only one wire or the cable involved in this transmission, it is less expensive. At the same time, if you are going to consider it,

There's a failure and this failure should not affect others. But if this link, this transmission medium is failed. Obviously, the entire network goes down. At the same time, if this node wants to send some data to this node and there is a problem in this line. So communication here can take place but the communication between this place will not happen. Why? Because this is not dealing with any alternative technique. The only way for this computer to reach this computer is this line.

there is no redundant line. And that is why this network is not a fall tolerant network. At the same time, the cable length is limited to certain range. Also, I have already mentioned, if this node wants to send some data to this node, every one participating in this network will receive a copy of this signal. So there is no security in this approach. And that's the advantages and disadvantages of bus topology. And coming to the second topology, the ring topology, is a bus stop.

Hello everyone, welcome to the next lecture in the computer network series and today we will see the basics of IP addressing. Now we will see the outcomes of this session. Upon the completion of this session, the learner will be able to understand the basics of IP addressing. We will also come to know how to see the IP address in real device and we will also identify valid and invalid IP addresses. Now we will move on to the definition of IP address.

9.173. So far we have seen how to see IP address in real device. There is an interesting activity for you. We are required to identify the valid and invalid IP addresses in the following set. So set of IP addresses are given and we are required to identify, valid and invalid IP addresses and place the options in the appropriate columns. And there are two columns given. One is the column for valid IP addresses, another one is for invalid IP addresses.

addresses. Suppose if you find A is a valid IP address, mark it as A here and if you find B is an invalid IP address, mark B here and you should know why they are valid and why they are invalid. Please pause this video for a while and make a note of this answer against the column. If you are done, compare your answer with the answer that I am depicting. So the valid IP addresses are A, C and D and the invalid IP addresses.

Any octet should be between 0 and 255, so 256 is not a valid entry, so B is invalid. Coming to CE, it is a valid IP address because each octet can be between 0 and 255, so CE is valid. And D is valid, why because D is also the last IP address of the IPv4 address set, and each octet is between 0 and 255, so D is valid. If you observe E, E is any

Invalid IP address, why because there is an octet with 2e? We know very well that IPv4 addresses must be in decimal, even if he is an hexadecimal character, but that is not valid here, because any IP address in IPv4 should be in decimal only, so F is also not valid. I hope this session will be helpful to understand what are valid IP addresses and what are invalid IP addresses. That's it guys, I hope now you understood the basics of IPv4.

addressing, you will also know how to see IP address in real device and we will be able to identify valid and invalid IP addresses. Thank you guys for watching.

an IP address. IP address IP stands for Internet Protocol. IP is an important part in the Internet and every node in the computer network is identified with a help of IP address only. We will see an example first and then we will come to the definition again. This example involves lot of end devices and lot of intermediary devices. Now there is a computer and this computer wants to send some data to the computer.

this computer. It means the computer with the IP address 172.15.150.2 is going to send some data to 192.168.150.2. So this is what we call as an IP address because every node in the computer network is identified with the help of IP address only. Now we will see more about IP address. When I say IP address there are two variations. IPv4 address

and IPv6 address. In this computer network series, we will be learning about both IPv4 and IPv6 elaborately in the upcoming lectures. For time being, now we will focus on IPv4 address. We already know every node in the computer network is identified with the help of IP address only and they are logical address too. Let me explain what is a logical address. If you take this scenario, this is a local area network which is in New Delhi. And this is another look.

network this is in Chennai. Suppose if I take this computer and if I place this computer in the local area network of Chennai and I want this new convert to participate in the local area network which is in Chennai I can simply remove this IP address and I can assign an IP address in this range. For example this computer is assigned with 192 168 152.2 and this is with 153 and this is with 150.4. So what I can give I can take this.

this computer and I can place it here and I can assign it as 192.168.150.5 and thereby we can make this new convert to participate in the local area network. Since this IP addresses can be changed based on the logic or the location we call IP addresses as logical address and that is what I have mentioned here. So IP addresses are logical addresses because we can change the IP address based on the location of the device.

And we can azine this IP address manually or even dynamically. We will talk about this point in the network layer part. Time being you just understand IP addresses can be azined manually or even dynamically. An IPv4 addresses are represented in decimal and it has 4 octets. It means 4 parts, say x.x.x.x.x. And each of this x takes a value between 0 and 0.

and 255. So this x can be between 0 and 255, likewise all the x can be between 0 and 255. So the starting IP address will be 0.0.0.0 to 255.255.255.255.255. And the total number of bits in every IP address will be 32 bits. We will now see how to see an IP address in real device. To view the IP address in real device, click the

Hello everyone, welcome to the next lecture in the computer network series. And today we will see the basics of MAC addressing. Before we start, we will see the outcomes of today's session. In today's session, we have three outcomes. Outcome number one, we will understand the basics of MAC addressing. Outcome number two, we will understand the difference between IP address and MAC address. And outcome number three, we will see the MAC address in today's session.

IP address we used to give IP config to see the mark address we are required to give the command IP config slash all. So this is the command that is used to see the mark address details. If you observe here I have an Ethernet adapter where I can establish my local area network with my Ethernet cable or I can also use local area network through Wi-Fi. In this case I have established my local area network through Wi-Fi.

And we will see what is the MAC address of this Wi-Fi adapter. So this is the physical address. We already know physical address means MAC address and 9.4 hyphen 39 hyphen e5 hyphen e7 hyphen 4c hyphen 60. And this is the MAC address of this computer now. Any data that goes from this computer, it uses this as the source MAC address. Suppose if somebody is replying to me and wants my Wi-Fi router receives this data and there may be hundreds of devices.

connected to my Wi-Fi router. My Wi-Fi router delivers the data to this computer by identifying this MAC address. So MAC addresses are very important in a local area network. So far, we have seen how to see MAC address in real device. That's it guys. We are now at the verge of completing this session. I hope now you understood the basics of MAC addressing and you understood the difference between IP address and MAC address and you also know how to see MAC address in real device.

Real Device. We will now move on to the basics of MAC Addressing. MAC Address MAC stands for Media Access Control. We will talk about this Media Access Control in the Data Link Layout part of our series. For time being you just understand MAC stands for Media Access Control. And every node in the local area network is identified with the help of MAC Address only. To understand more about this we will take an

analogy. IP addresses are like the location of a person. Suppose if a person is in Delhi, his location is Delhi. If a person is in Mumbai, his location is Mumbai. If a person is in London, his location is London. So IP addresses are like the location of a person. Wherever the person goes, his location gets changed. But MAC addresses are like the name of the person. Wherever he goes, his location may get changed, but his name will not get changed.

So, that is what the difference between an IP address and a MAC address. We will see an example now. In this example, we have many end devices and many intermediary devices. Suppose, if this computer wants to send some data to this computer and this communication happens with the help of both IP address and MAC address. Actually, routers need IP address and switches need MAC address. For example, this is the source and it wants to send.

send some data to this receiver or the destination. With data it is going to send, it is going to add IP address and MAC address. When the router receives this packet, it takes the forwarding decision based on IP address. Once the data is received by this switch and it is the responsibility of this switch to deliver the data to the right destination. So switch gives the data to the right destination based on the MAC address. So IP addresses are router friendly addresses and MAC addresses are

time, these MAC addresses cannot be changed. Why? Because these MAC addresses are assigned by the manufacturer. And the MAC addresses are represented in hexadecimal. An example hexadecimal value that is the MAC address is shown here. 70 hyphen, 20 hyphen, 84 hyphen, 00 hyphen, ED hyphen, FC. This is an example MAC address. And this MAC address is of 48 bits. And this separator in the MAC address is decided by the manufacturer.

Hello everyone, welcome back to the Computer Networks course. Today we will see the classification of computer networks. After completing this session, we will understand what are LAN, Man and Van. And after understanding LAN, Van and Van, we will also understand what are the devices that are involved in LAN, Man and Van. And we will also understand what are the new trends in computer networks. We will see the classification of computer networks. Computer networks are classified into local area network or simply LAN.

First we will see what is a telecommunications network. Any communications at a distance we call it a telecommunication network. So here the communication is going to be within a large geographical area. In man, two or more lands within a city can communicate with each other. In van, two or more lands within a country can communicate with each other. And the devices in van are all end devices and intermediary devices. Because an end device in one part of the city can communicate with each other.

The country may want to communicate with an end device which is in the other part of the country and some authors will refer this wide area network to be the internet. We will see an example now. And there are two local area networks. One local area network is in New Delhi and other local area network is in Chennai. And these two local area network are in two different places in the country and they are separated by a very large geographical area. But still this computer can communicate with this computer. And this is part of the country.

possible only with the help of a wide area network. Wide area network means communication at a large distance. If it is a man, this is possible only within a city. But this is wide area network, hence the communication at a distance is still possible. So far we have seen, local area network, metropolitan area network and wide area network. Now we will see the internet. I will say this is a wide wide area network, that is a wide van. Because there are so many local areas.

and it works so many metropolitan area networks and so many wide area networks across the world are connected to each other. Say for example, there is a guy in India who wants to send some data to a guy who is in Australia. Between India and Australia, there are many routers involved in taking the data from India to Australia. Similarly, every country in the world is somehow connected with other countries through computer networks. We don't know whether two countries have a friendly relationship or not, but definitely they will have a computer network relationship. And that's the part of the question.

computer network guys. Before we conclude, we will see the new trends in computer networks. Nowadays, many employees are encouraged by their employers to bring their own device and connect to the office network. And we shall call such scenario as a bring your own device scenario. It means employees can bring their own device and connect it to their office network and still work with the office network. Coming to the online collaboration, once upon a time, if a meeting is scheduled, everyone has to assemble in the meeting spot.

It is the on demand availability of computer resources. First let's take an example. Let's take Google Drive. One can store all files and folders in Google Drive that gives a lot of flexibility. If one wants to access his files from any part of the world, he can access by just giving a request to Google Drive and download the data. What if he had stored the data in his personal computer? He needs to carry the computer wherever he goes if he wants the data with him. But cloud computing says this Google Drive offers this on demand availability. If you want to access his files, you can use Google Drive to access his files. And if you want to access his files, you can use Google Drive to access his files. And if you want to access his files, you can use Google Drive to access his files. And if you want to access his files, you can use Google Drive to access his files. And if you want to access his files, you can use Google Drive to access his files. And if you want to access his files, you can use Google Drive to access his files. And if you want to access his files, you can use Google Drive to access his files.

Cloud computing is the on-demand availability of computer resources, especially data storage and this computing. We need not directly involve in the management. We can just store the data somewhere in a secured manner and get the data whenever we want it. That's the power of cloud computing. That's it guys. In the initial part of the session, we have listed that we are going to learn certain things. Now we will ensure whether we have learned all these things. I hope now you have learned what is local area network, metropolitan area network and wide area network.

And we have also seen what are the various devices involved in LAN, Man and Van. And there are some new trends that are there in the computer networking field. And we have also seen those trends. Thank you for watching.

Let's take an example. Let there are 100 computers in a network. And this is a school network. Each of these computers are connected to each other with the help of a switch. And we can call this computer network as a local area network. Why? Because all these computers can communicate with each other internally. We can set up LAN in two ways. One is a wired LAN, another one is a wireless LAN. In wired LAN we have cables. So the example technology for a wired LAN.

is Ethernet. We have already seen in the previous lecture that Ethernet is used to connect to our more nodes. In this case, this node is connected to the switch. This computer is connected to the switch with the help of an Ethernet cable. To be precise, this is an Ethernet straight through cable because Ethernet straight through cable connects devices of different kinds. Switch and computers are different kinds of devices. So we need to use Ethernet straight through cable. In case if we want to connect this computer with this computer directly, then we have

have to go for Ethernet crossover cable. Whatever it is, Ethernet is the well known and the most popular technology in wired LAN. And the devices that are used in the wired LAN are hub and switch. I will talk about this hub and switch in the next lecture elaborately. Now you just understand hub or switch can be an intermediary device in a local area network. And that too in a wired local area network. We can also have a local area network wireless, example Wi-Fi. Now we will see metropolitinalia network.

or simply man. A metropolitane area network is a computer network that interconnects users or computers in a geographic region. See there are two branches in a city and these two branches are somehow connected with each other. So this kind of network is called as a metropolitane area network. In other words there are two local area networks. These two local area networks are connected to each other in a city. The devices involved in this metropolitane area network are

switches hubs for establishing a local area network and to connect two local area networks we need routers or bridges. As I already mentioned there are minimum two local area network and these two local area networks are to be connected with each other with a helper router or a bridge. We'll see an example now. There are four local area networks connected to each other. Let's take this is a super market and this super market has four branches. Computers in one super market will be in one local area network.

Similarly, other branches also have separate local area network and these supermarket branches must somehow communicate with each other. For example, if someone is asking for a product which is not there in this branch, the employee of this branch wants to search whether the product is available in other branches. This is possible only if all local area networks of the supermarket are connected and this is what exactly a metropolitan area network. Please remember this is restricted to only a small geographic region like a small

Please note in every land there are some computers and these computers can communicate with other computers in other local area network. And this is possible only if these computers are somehow connected with each other. Time to see wild area network, that is the van. A wild area network is a telecommunications network that extends over a larger geographical area. It means it is a telecommunications network but it deals with a larger geographical area.

Hello everyone, welcome back to the Computer Networks course and today we will see the various components of a computer network. Upon the completion of this session, we will be able to understand nodes, we will also understand what are the different media in computer network and what are the various services offered by computer network. Any computer network has three components, nodes, media and services. Firstly, we will deal with nodes.

is going to be carried in the form of light waves. We know very well that light is the fastest one in the world. Since this cable takes the data in the form of light waves, this is the fastest to mode of wired communication. Now we will see coaxial cable. This is an example coaxial cable. This cable is mainly used for audio or video communication. We can see this cable in our home. If you have a set of box, just go and see this coaxial cable which connects to

the dish antenna and the set of box. This cable also carries the data in the form of electrical signals. And coming to USB cable, USB stands for Universal Serial Bus. This cable is used to connect a computer and a smartphone. We know very well if we want to connect our computer to a smartphone, most of us will prefer this cable only. And we are done with wired media. Now we will move on to wireless media. Two or more devices.

are going to communicate with each other but without the help of a cable. Here, R is the medium that carries the data from one node to other. In wired networks, data are converted into signals. Maybe electrical signals or light signals. Whereas in wireless network, data are converted into waves. Coming to the wireless media, we have infrared waves, radio waves, microwaves and satellite waves. Infrared waves are mainly used for short range of waves.

of communication, example, TV remote control. The wave between the remote control and the television is an infrared wave and if the distance between the TV and the remote control increases, this communication cannot happen because infrared are used for short range communication. Coming to the radio wave, the range of this radio wave is higher than infrared. Blue tooth and Wi-Fi uses radio waves. The next one is the microwaves. Cellular system. R cell phone

technology uses microwaves. Microwaves are used for long distance communication when compare to radio waves or infrared waves. And finally the satellite communication. And this is ultimately the long distance communication. Our GPS enabled cell phone gives signal to the satellite and the location of this device is identified with the help of this signal. So far we have seen nodes and media. Two types of media are addressed via media and wireless media. This is

scenario involves both wired media and wireless media. This straight lines represents Ethernet straight through cables. Just recall what are Ethernet straight through cables, say a computer with a switch, a switch with a printer, a switch with a router, a wireless router. But Ethernet cross-over cables are used to connect devices of similar type. Between routers we use only straight through cables. Ethernet straight through cables and dashed lines are cross-over cables.

So, this is an example for a wired media. At the same time, our example also uses wireless media. In this case, between smartphone and cell phone tower wireless technology is used, between smartphone and wireless router, between tablet and wireless router we have wireless technologies. To be specific, here microwaves are used because this is a long distance communication. And here radio waves are used because this is a Wi-Fi router and smart device. So, this is a long distance communication.

longer distance communication when compared to this communication. We will now see the third component of a computer network services. We use computer network for sending mails or receiving mails, storing our data in a remote computer, Google Drive is an example for storage. We can share files using computer network, we can send instant messaging like WhatsApp, using computer network, we can play online games using computer networks, we can make voice calls using voice over IP, we can also run it.

do video calls or video conferencing using video telephony and we can also use computer network for surfing internet that is accessing websites. We have already seen about nodes and media and the last part here is the services. This scenario involves many kinds of services. Suppose if this guy is sending some message to his friend through WhatsApp so it uses instant messaging and two people are talking over voice over phone. So this is voice communication is happening.

We have already seen nodes in detail in the previous lectures. A node can send or receive or both send and receive the data. And these nodes can be an end node or an intermediary node. We can call end nodes as end devices and intermediary nodes as intermediary devices. We will first see end nodes. End nodes are the nodes that is going to be the starting point of the communication or the end point in the communication. If two devices wants to communicate with each other,

like smartphones, tablets, personal digital assistance, wireless debit or credit card reader, barcode scanner and many more. We are done with end nodes. Now we will see some examples for intermediary nodes. Intermediary nodes are nodes that just forwards the data from one node to another. In other words, they are going to be placed in between end nodes. Which is wireless access points, routers, security devices like firewall, bridge,

Bridges, Hubs, Repeaters, Cellphone Tar etc. If you feel any of these terms are new, no worries, we are going to deal elaborately about all the terms in detail in the upcoming lectures. There are lot of end devices and intermediary devices involved in this scenario. These devices, smartphone, voiceover IP phone, printers, desktop computers, tablet and web servers, these are all end devices. Bridges, Cellphone Tar etc.

iPhone Tower, this wireless router, these routers and this switch, they are intermediary devices. We are done with nodes. Now we will move on to the media. Media. It is also called as the link. We know very well that the link is going to carry the data from one side to the other. This link or this media can be a wired medium or a wireless medium. Some authors refer wired medium as guided medium and wireless medium as unguided medium.

there will be a cable that connects two nodes. Whereas in a wireless medium, cable will not be present. Since cable are used to guide the data flow, we call wired medium as guided medium. Whereas there is no cable in a wireless medium. And that is why we call wireless medium to be unguided medium. We will see some examples for wired medium and wireless medium. The examples for wired medium are Ethernet cables, fiber optic cable, coaxial cable and UL

as B cable. We will see each of these cables in detail now. Firstly, Ethernet cable. This is an example of an Ethernet cable. Ethernet cable is an example of a twisted par cable. I will talk about twisted par cable in the upcoming lectures. For time being, you just know this is an Ethernet cable and this Ethernet cable comes into variation. One is Ethernet straight through cable and Ethernet cross over cable. We will see the difference between this Ethernet straight through cable and Ethernet cross over cable.

If we want to connect different devices, we have to go for Ethernet straight through cable. In case if we want to connect two devices of same kind, say two switches or two routers or two computers wants to be connected to each other, then we have to go for Ethernet crossover. In Ethernet cable, the data is going to be carried in terms of electrical signals. So far we have seen Ethernet straight through cable and Ethernet crossover cable. Now we will move on to fiber optic cable. In fiber optic cable, the data is going to be carried out.

Hello everyone, welcome back to the Computer Networks course and today we shall see the basic characteristics of computer network. Before we step into the basic characteristics, we shall set some outcomes of this session. Upon the completion of this session, we will be able to understand the need for fault tolerance networks and scalable networks. We shall understand what is quality of service and we shall also understand why do we need security in computer networks. Today are 4 basic characteristics.

previous lecture, it is the voice over IP phone. Vivo IP stands for voice over IP phone and this phone is different from our traditional landline phone. This voice over IP phone sends the voice data through the internet whereas our traditional landline phone sends the voice data through the dedicated telephone network. So this voice over IP phone is like our whatsapp call. Our voice data is sent to the destination through the internet.

but not through the telephone network. You may be wondering why I have brought in this voice over IP phone. I shall explain you why I have brought in this voice over IP phone. For a reason, let's assume this guy is sending some email data to an email server through router 1. At the same time, there are two guys who are talking over voice over IP phone through internet. The situation is, two guys are sending data at the same time and this router 1 is experiencing both the same.

the traffic at the same time. One is the email traffic, another one is the voice traffic that is the real-time communication. Now the question is to which data this router one will give priority, whether to the real-time communication or to the email data. Actually, router one will process voice over IP phones data. Why because it is a real-time communication? In real-time communication, delays are not accepted. Whereas, delays are not a problem.

in email communication. A delay of one second in an email communication is not going to hurt the communication. Whereas a delay of one second in a real-time communication matters a lot. And that is why this router gives priority to real-time communication than normal communication. When router experiences two different kinds of data at the same time, this router should be able to know to which data it should give priority. This is what we call as quality of service.

The main aspect of this quality of services that it handles loss also it handles the delay. Now we shall see the final characteristics of computer network that is the security. It is the ability to prevent unauthorized access, misuse or forgery. And not only prevention, network should also provide confidentiality, integrity and availability. To understand why do we need security, we shall visit this example. So

Suppose someone from this computer is sending some confidential information to amazon.com. Once the data leaves our computer, it is not in our hands. Internet has good guys as well as bad guys whom we call as attackers. Please note attackers are bad guys. Assume our confidential information is flowing through router 3 and what if an attacker steals this information from router 3. They get access to our computer, they can misuse or

they can also involve inforgery. So it becomes an important task for a computer network to provide confidentiality. That is, the data which is not sent just like that as what we had sent. It means if it is a confidential data, this data is converted to a different form. If that form can be understandable only by the sender and the receiver. At the same time, there is no modification of data sent should be there. That is, this network should provide

sticks any computer network should possess. Fall tolerance, scalability, quality of service, and security. If we say there is a computer network, and that computer network should be fall tolerant, it should be scalable, it should provide quality of service, and it should also provide security. We shall see each of these in a detailed manner. Firstly, fall tolerance. Fall tolerance is the ability of the computer network to continue working.

despite failures and it should ensure there is no loss of service. For example, if we have a computer network and if there is a problem inside the computer network but still the computer network should work even after failures and thereby there is no loss of service. Before we go on to this example part you just visualize this scenario. Imagine you are going home back from your college. You know very well about the best route to reach your home and you prefer taking this regular best route. Unfortunately,

Secondly, there is a blockage and you cannot take this route further. What will you do now? Will you go to your college back or you will find the next available route to reach your home? I guess we all will find the next available route and we will take that route to reach home. This is what we call as fault tolerance. We shall see an example for fault tolerance now. Let us assume that these two entities are communicating with each other. This computer and this web server. You switch this one.

There is a router, this link, this router 1, router 3, router 5, switch and web server. Unfortunately there is a failure, maybe either in the link or this router has gone down. So this router, instead of forwarding the data to this way, it forwards the data to router 2, so that this communication between this computer and this web server is not affected because of this failure. This is what exactly fault tolerance. I hope.

Hope now you understood why do we need fault tolerant network? Because we need to work despite failures and we need to ensure there is no loss of service. This is what exactly fault tolerance. Now we shall see the second basic characteristics scalability. It is the ability to grow based on the needs and have good performance even after growth. For example, if there are 10 computers in a network and if again 10 computers are added

to the network, this network should work as like the same even after adding these 10 computers. We shall see an example for the scalable network. The best example for a scalable network is the internet. Even this moment many new devices are connecting to internet and communicating to each other. Internet handles this very perfectly and always gives scope for the new comers. This is what we exactly call as scalability.

In this example, assume 100 computers are connected to router 3 and we expect our computer network to work as like the same even after adding these 100 devices. This is what we call as scalability and this is the ability to grow based on the needs and have good performance even after the growth of the network. So far we have seen fault tolerance and scalability. Now we shall see the third basic characteristic of computer network.

Hello everyone, I welcome you all to this wonderful course on Computer Networks. I'm your instructor here to take you throughout this journey on Computer Networks. Before we start, let's figure out to whom this course is actually intended to. This course is mainly for the undergraduate students. And this course is useful for the students who are preparing for their gate exams. And not only gate exams, this course will surely help the students to craft networking based interviews. This course can be a prerequisite course to CCNA International Certificate.

It comes under wired category. So wired link carries the information from this computer to this computer or vice versa. But there are scenarios where two devices wants to communicate with each other but not with the help of cables. Say in this scenario, these two smartphones wants to exchange data. Say, this phone wants to give some data to this phone. In this case, there is no physical connectivity. Then how can be that communication be established? This is possible through wireless technologies. That is it.

is going to carry the signals. Obviously R is going to carry the data. So here, R is the link that carries the data from one place to another place. So we have two kinds of communication links. One is a wired link, another one is a wireless link and the link only carries the information. We shall see some examples. Cable is a best example for wired link and R is the best example for wireless. Now let's take this example where this example

example involves lots of nodes and so many links. If you observe certain links are wired links and certain links are wireless links. So this is a perfect example of a sample computer network. Now what are all the devices or nodes involved in the network? This printer is a node. They stop computers or nodes. Tablet is a node. This smartphone is a node. Cell phone tower is a node. This wireless router is a node. Router, Internet Cloud. See there are

save a lot of infrastructure cost as well. And there is an interesting scenario for you. You have to find out what all the end devices used in the scenario and what are the intermediary devices. After finding out all the end devices and the intermediary devices, just list it out like this on your paper. So I am showing this scenario for you. Please take a piece of paper and note down all the end devices and intermediary devices. Please pause this video for a while.

I and carry out this task. Once done, you compare this with the actual result. Now if your result is matching with this result, congratulations to you. You are progressing in a right direction. If not, no problem guys. We are in the initial stage. It will take some lectures to understand the details about networking. Upon this completion of this lecture, the learner will be able to understand what is computer network.

And if you want to demystify all the networking technologies and jargons used in the networking field, this course will show ourly fulfill your expectation. In an actual, this course will surely quench the thirst of computer networking. And coming to the scope of this course, trust me guys, networking is everywhere. Because network supports a way we learn, network supports a way we communicate, network supports a way we work and the way we play. I shall explain you how network supports a way we learn.

and even voice calls and video calls which are real-time communication. We are able to do all this communication seamlessly and perfectly with the help of computer networks. Isn't the computer network awesome guys? Network supports the way we work. Yes, one can work from home by accessing the files and software actually available in the company. And network supports the way we play too. Talking about the pedagogy, we need to understand the theoretical background of all the concepts.

We go with the traditional lecturing methods and the contemporary lecturing methods. As I already mentioned you, that we will be solving many gate examination related problems here in this course. And to understand the things, practically, worlds one of the most powerful simulation and learning tools the Cisco packet treasure is used. And talking about the syllabi, in the first phase of the computer networking course, the fundamentals are dealt elaborately. Actually, computer networks follow SLAIN to send it.

and they will be able to identify end devices and intermediary devices if the scenario is given. We'll start with the definition of a computer network. A computer network is a set of nodes connected by communication links. I repeat, a computer network is a set of nodes connected by communication links. To understand this definition, I shall highlight the important words they are the keywords of this definition. The keywords are nodes and communication links. First, we'll call it a computer network.

concentrate on nodes. A node can be a computer, printer or any other device capable of sending or receiving data. Say you have a device if that device can send data or receive data or both send and receive data then we can call that device as a node. So a node can be a computer, printer or any device but the important point to note here is that device should be capable in us in sending or receiving the data. We shall see some more.

examples for nodes. Obviously a computer is a node because a computer can send data as well as receive data. A server, printer, security camera and many devices like switches, bridges and routers are also called as nodes. We will be dealing about switches, bridges and routers in the upcoming lectures. Now we are done with nodes. We will concentrate on what our communication links. A communication link can be a wired link or a wireless link. The important point

Hello everyone! Welcome back to the course on computer networks. Today we shall see network protocols and communication. Before we step into the topic, we shall understand what are the things we are going to learn today. Today we will be learning about data communication, data flow, what are the importance of protocol in computer network. Understand guys, protocols are very important in computer network and what are the elements will also be addressed in today's session. Now we shall see what is data communication.