A router disperses digital computer data which the data packet contains. The data packet contains information on addresses that a router uses to decide if the data packet needs to be sent from one network to another or if the destination and source are on an identical network. The other type of network transfer is brought about by summarizing the information with protocol header information that is network specific. Within a large collection of interconnected networks where multiple routers are used, the routers trade information concerning target system addresses, so each router can erect a “table showing” which is the desired path between every system on interconnected networks.
A router may have a variety of interface connections for networks of different physical types such as wireless transmission, fiber optic or copper cables. The router may have firmware for network protocol standards. Every network interface device is dedicated to convert a computer’s signal between protocol standards.
Routers are sometimes used to connect several logical subnets whose network addresses are different. The addresses of the subnets in the router may not actually lead directly to the router’s physical interfaces. The term routing and layer 3 switching are often used interchangeably. Switching usually refers to data forwarding that is between two network devices that have identical network addresses. This is known as LAN switching or layer two switching. A router runs in two sub systems or operational planes which are:
- In a forwarding plane the router forwards traffic, which is called data packets, from interfaces that are incoming to destination addresses of outgoing interfaces that are contained in the packet header.
- In a control plane a router builds up routing tables which are called address tables, and records the destination a packet should be forwarded to and through which physical interface it should go.