On
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 networks 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 Internet point-of-presence.
A router is often included as part of a network switch.
A
router may create or maintain a table of the available routes
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 standard model of network
programming, 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.
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