BGP

An inter-Autonomous System (AS) protocol like the Exterior Gateway Protocol (EGP), BGP is concerned with conveying routing reachability information between groups of routers that fall within a single administrative domain. Although EGP runs on top of the Internet Protocol (IP), BGP runs on top of the Transmission Control Protocol (TCP), thereby ensuring a connection-oriented data flow and reliability of datastream transport.The IETF described the current version, BGP-4, in RFC 1771. BGP is assigned TCP well-known port number 179 and supports Classless InterDomain Routing (CIDR). See also AS, CIDR, connection-oriented, domain, EGP, IETF, IP, port, protocol, routing, TCP, and well-known port.