Routing

In computer networking, routing is the process of receiving a packet on one interface of a router, validating the packet, and, assuming the router knows that a particular outbound interface will move the packet one hop closer to its final destination, forwards it out that interface.

Routing is not terribly difficult than driving to a destination along a set of highways. Each exit sign informs the driver of a set of destinations reachable through that exit. The driver will decide to take the exit if it goes toward the destination, or will continue looking for a better exit.

The process that draws the "map" of the network, or, in the highway analogy, puts the list of destinations on the exit sign, is the control path of the router. The process that actually moves the packet from input to output is the forwarding path.

The device that performs these functions is called a router. Physically, a router is usually a special-purpose computer, although it is possible to program a personal computer to route.