A router is a device that determines the proper path for data to travel between different networks, and forwards data packets to the next device along this path. They connect networks together; a LAN to a WAN for example, to access the Internet. Some units, are available in both wired and wireless models.
Wired Router Model
Wireless Router Model
Function
A more precise definition of a router is a computer networking device that interconnects separate logical subnets. Routers are now available in many types, though all are fundamentally doing the same job. A router is a computer whose software and hardware are usually tailored to the tasks of routing and forwarding, generally containing a specialized operating system (e.g. Cisco’s IOS or Juniper Networks JunOS or Extreme Networks XOS), RAM, NVRAM, flash memory, and one or more processors. High-end routers contain many processors and specialized Application-specific integrated circuits (ASIC) and do a great deal of parallel processing. However, with the proper software (such as XORP or Quagga), even commodity PCs can act as routers.
Routers connect with two or more logical subnets, which do not necessarily map one-to-one to the physical interfaces of the router.
The term switch or layer 3 switch or network switch often is used interchangeably with router, but switch is really a marketing term without a rigorous technical definition (though a switch is commonly understood as a network hub with switched ports, which might or might not also perform additional routing functions).
Chassis systems like the Nortel MERS-8600 or ERS-8600 routing switch, allow for a wide variety of LAN, MAN, METRO, and WAN port technologies or other connections that are customizable.
Routers operate in two different planes:
