An inter-Autonomous System (AS) protocol concerned with conveying routing reachability information between groups of routers that fall within a single administrative domain. EGP runs on top of the connectionless Internet Protocol (IP) and is assigned well-known port number 8.The Border Gateway Protocol (BGP), which builds on and enhances EGP, runs on top of the Transmission Control Protocol (TCP), thereby ensuring a connection-oriented data flow and reliability of datastream transport. EGP was described in IETF RFC 827 (1982). See also AS, BGP, connectionless, connection-oriented, domain, IETF, IP, port, protocol, routing, and TCP.