Core Issue
Border Gateway Protocol (BGP) is an inter-autonomous system routing protocol used to exchange network reachability information between routers. BGP uses Transmission Control Protocol (TCP) as the transport protocol (TCP port 179). BGP routers form TCP connections with other BGP speaking routers configured as neighbors. Internal BGP (iBGP) runs if the BGP neighbors lie in the same Autonomous System (AS), while external BGP (eBGP) runs if the BGP neighbors lie in different ASs.
Resolution
For frequently asked questions about BGP, refer to BGP: Frequently Asked Questions.
