Before going into the technical details about a router, consider your local mail man. He delivers your mails based on the address written on the top of your mails. You may send a mail from one country to another and even then they are redirected to the correct post offices and finally the mail man delivers it to the intended destination. This exactly, is the function of the router. In the internet communication or data transfer is in the form of packets. These packets are delivered to the destination with the help of the destination address associated with each packet.
** How Does A Router Work?
A router basically forwards the packets across two different networks. It is basically used for interconnecting different LANs or WANs. The internet is made possible with the help of many routers. The function a router performs is termed as routing.
The incoming packets are queued at one end of the router. Each of these devices has customized hardware and software which determines the best route based on the routing algorithm configured on the router. They are normally placed at the gateways which are the point of connection between different computer networks.
Normally we use home routers to connect our machine to the internet. These routers are termed as IP routers (Cable modem or DSL).
Routers are devices that works on the Layer 3 (Network Layer) of the OSI model. They do work on Layer 1 (Physical Layer) and Layer 2 (Data Link layer), but the routing decisions which include which path to take etc are done on the third layer. They work on IP addresses and when a packet arrives, it strips the header, analyzes the source and destination address and forwards it accordingly.
Routers have tables configured with details of the neighboring routers and connected devices so that they can quickly decide which route to take rather than flooding the network with request to know the destination. ICMP and other such protocols are used for inter router communication and route configuration.
** Why Do We Need A Router?
Normally it is almost impossible to communicate between two different networks directly because they would be completely different in terms of architecture, data formats used, data representation and such factors. Even if we send data directly, the destination may get this data in an unrecognized data format.
They also connect different networks that do not share the common network address. In case of huge companies, they may use private IP addresses within their network. if computers in that network need to communicate with the internet or another network, they need a public IP which the router will take care of. Normally it is implemented in proxy servers but routers are also able to handle them.
You will also need a router if you have several computers in your LAN and need to connect it to the internet. A switch may be a logical alternative, but it all depends on your requirements. L3 switches are an alternative to routers, but they are costly. Again, in corporate environments L3 Switches may be used due to the flexibility they provide. Need to connect to the internet even easier, you can choose the best wireless routers 2017 on the market because you can connect without any cables at all, all can be done wirelessly.
Types Of Routers
1. Core router
2. Inter-provider border router
3. Subscriber edge router
4. Edge router
5. Wireless Router
Various Routing Protocols Used