Classification of Computer Networks

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 WAN. And after understanding LAN, WAN and MAN, we will also understand what are the devices that are involved in LAN, MAN and WAN. And we will also understand what are the new trends in computer network. We will see the classification of computer networks. Computer networks are classified into Local Area Network or simply LAN,

Metropolitan Area Network or simply MAN,

Wide Area Network or simply WAN.

We will see Local Area Network first. As the name implies, Local means it is restricted to a limited area. That is, a small network is said to be a local area network. A Local Area Network is a computer network that interconnects computers within a limited area. A small network that is there in our residence, or a school, lab, university campus or office is said to be a Local Area Network.

Let's take an example.

Let there be hundred 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 setup LAN in two ways:

1. one is a wired LAN 
2.  another one is a wireless LAN.

In wired LAN we have cables. So the example technology for a wired LAN is ethernet ethernet is used to connect two or 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 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.an intermediary device in a local area network. And that too in a wired local area network. We can also have a wireless local area network. Example: Wi-Fi.

Now we will see metropolitan area network or simply MAN.

A metropolitan area network is a computer network that interconnects users or computers in a geographic region. Say 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 metropolitan 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 metropolitan 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 the help of a router or a bridge. We will see an example now. There are four local area networks connected to each other. Let's take this is a supermarket and this supermarket has four branches. Computers in one supermarket 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 is exactly a metropolitan area network. Please remember this is restricted to only a small geographic region like a city. Please note in every LAN 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.

It is time to see wide area network that is the WAN

A wide area network is a telecommunications network that extends over a large geographical area. It means, it is a telecommunications network but it deals with the larger geographical area. First we will see what is a telecommunications network. Any communication at a distance, we call it as a telecommunication network. So here, the communication is going to be within a large geographical area. In MAN, two or more LAN's within a city can communicate with each other. In WAN, two or more LAN within a country can communicate with each other. The devices in WAN are-- all end devices and intermediary devices. Because an end device in one part of the country, may want to communicate with an end device which is in the other part of the country. And some authors will refer to this wide area network to be the internet. We will see an example now. 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 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 i.e. a wide WAN. Why because, there are so many local area networks, so many metropolitan area networks and so many wide area networks, across the world are connected to each other. 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 network. We don't know whether two country have a friendly relationship or not. But definitely they will have a computer network relationship. And that's the power of computer network guys. 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. Now the trend has completely been changed. They can participate from wherever they are and they can still do online collaboration with others with the help of computer network. Say for example, a meeting involves participants in New Delhi, Chennai, America, Australia but still no one to be there in a particular or a specific location. They can be wherever they are, but still they can do online collaboration. And cloud computing is the new trend that we would like to address. Cloud computing means 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, say this Google drive offers this on-demand availability. 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 is the power of cloud computing.