Neighbor Negotiation

Neighbor Negotiation
Before BGP communications can occur, BGP speakers must become neighbors, or peers. The
first step in forming a peer is for the BGP speakers to form a TCP session with each other using
TCP port 179. If this does not occur, the BGP speakers will never become peers. After the TCP
session has been established, the BGP speakers send an OPEN message to each other. From that
point forward, the BGP speakers send incremental UPDATE messages, NOTIFICATION messages,
and KEEPALIVE messages.
The process through which the forming of neighbors occurs is known as the finite state
machine.