Overview
Routing involves two activities: determining the optimum path to every destination in the network, and transporting groups of information typically called packets through the network. While transporting packets through an internetwork is relatively straightforward on the surface, determining the best path to every destination within the network can be very complex.

Routers use routing protocols to speak among themselves and determine the best path to the various destinations within the network (or internetwork, which is simply a large collection of networks); one of these routing protocols is the Border Gateway Protocol (BGP). BGP performs interdomain routing in TCP/IP networks. This chapter summarizes the basic operations of BGP and provides a description of its protocol components.