CCIE: BGP
Unlink IGP’s, BGP does not use metrics to select best path. Instead, BGP is vector based. This path is determined with Path Attributes (PA’s). The default PA, if no others are set is AS-PATH. Shortest path to destination prefix is the best path. Building the neighbor relationship: TCP Port 179 (established based on neighbor address), Open, Established, and finally Updates (contains the prefix information). If there is a problem/error a “notification” message is sent. Keepalive is 60 and hold time is…