There are various networking devices that can be used to work with different computers in a network. Switches, bridges, and others can also be used. But a router is one of the most powerful devices that can be used to work with different layers of a network. A network does not only comprise of the hardware. The software integration of a network is generally divided into layers, each of which has certain functions and would be implemented with the help of the lower layer. Routers are, therefore, networking devices, that can be used to forward data packets between different computer networks. It performs the different traffic directing functions on the network. Thus a large network would mean that a data packet typically travels from one router to another till it reaches the destination through an internetwork.
The routers are connected to two or more different data lines from different networks. When the data packet would come in through one of the lines, the router would read the address information on the network and would then determine the ultimate destination of the packet through the routing table. The routing table or routing policy would provide information which would direct the packet on the next network on its journey. There are various internet routers available, the most common ones being those used in homes and small offices, used to pass IP packets between two different nodes or terminals. Routers are typically dedicated hardware devices that form the backbone of any network.
Internet routers can help in transferring data packets between the home and the Internet. This could be the cable of the owner or the DSL router, connecting the Internet through an Internet Service Provider. Information can be exchanged between multiple networks about the destination addresses through a routing protocol in the case multiple networks are being used. Each of the routers would build up a routing table that would list the preferred routes between two systems on the networks.
The internet routers would generally be working on two different planes - the control plane and the forwarding plane. Through the control plane, the router would be maintaining a routing table that would list which route should be used to forward the data packets and the physical interface connection that is to be used. Preconfigured directives or static routes are to be used for this or dynamic routes that are learned using a routing protocol. The logic driving the control plane would then remove the non-essential directives and build a forward information base.
The forwarding plane, on the other hand, would channel the data packets between the incoming and the outgoing interfaces. It directs the packets according to the information on the packet header by matching the entries in the FIB maintained by the control plane. Thus routers can be used to form connections between different networks and different nodes and transfer data packets at high speeds.