When BGP establishes a peer connection, both this segment and the peer end will initiate a TCP three-way handshake, so two TCP connections will be established, and then one connection will be used…

When BGP establishes a peer connection, both this segment and the peer end will initiate a TCP three-way handshake, so two TCP connections will be established, and then one connection will be used for BGP message exchange, and the other will be closed. If the Router ID of this segment of the BGP peer will compare the size of the local Router ID and the peer Router ID, if the local Router ID is smaller than the peer Router ID, it will be closed. The locally established TCP connection can use the TCP connection actively initiated by the peer. Subsequent BGP message exchange.