Exterior Gateway Protocol

The Exterior Gateway Protocol (EGP) is a now obsolete routing protocol for the Internet originally specified in 1982 by Eric C. Rosen of Bolt, Beranek and Newman, and David L. Mills. It was first described in RFC 827 and formally specified in RFC 904 (1984). EGP is a simple reachability protocol, and, unlike modern distance-vector and path-vector protocols, it is limited to tree-like topologies.
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(EGP) A protocol which distributes routing information to the routers which connect autonomous systems. The term "gateway" is historical, and "router" is currently the preferred term. There is also a routing protocol called EGP defined in STD 18, RFC 904. See also Border Gateway Protocol, Interior Gateway Protocol.