Prologue Hey fellow CCIE’s candidates and networking geeks. Today I want to step deep into the realm of PfR or Performance Routing. First let’s go back in time to the predecessor, Optimized Edge Routing or OER. As crazy as this sounds, OER came out in 2006 with IOS 12.3 . So, technically before all this SDN fanfare, Cisco actually decoupled the control (part of it at least) and data plane with OER/PfR back in the dizay. DID THAT JUST BLOW…
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…