BFD for BGP
The Border Gateway Protocol (BGP) periodically sends Keepalive packets to a peer to monitor the peer's status. However, BGP takes more than 1 second for fault detection. When traffic is transmitted at gigabit rates, lengthy fault detection causes packet loss, which does not meet carrier-class network requirements for high reliability.
Bidirectional Forwarding Detection (BFD) for BGP can quickly detect faults on the link between BGP peers and notify BGP of the faults, which implements fast BGP route convergence.
Networking
As shown in Figure 2-14, Device A and Device B belong to ASs 100 and 200, respectively. The two routers are directly connected and establish an External Border Gateway Protocol (EBGP) peer relationship.
BFD is enabled to detect the EBGP peer relationship between Device A and Device B. If the link between Device A and Device B fails, BFD can quickly detect the fault and notify BGP.
