In packet-switched networks such as the Internet, a router is a device or, in some cases, software in a computer that determines the next network point to which a packet should be forwarded toward its destination. The router is connected to at least two network and decides which way to send each information packet based on its current understanding of the state of the networks it is connected to. A router is located at any gateway where one network meets another, including each point-of-presence on the Internrt. A router is often included as part of a network switch.
A router may create or maintain a table of the available routers and their conditions and use this information along with distance and cost algorithms to determine the best route for a given packet. Typically, a packet may travel through a number of network points with routers before arriving at its destination. Routing is a function associated with the Network layer (layer 3) in the Open Systems Interconnection (OSI) model. A layer-3 switch is a switch that can perform routing functions.
An edge router is a router that interfaces with an asynchronous transfer mode (ATM) network. A brouter is a network bridge combined with a router.
