BFD for BGP
Bidirectional Forwarding Detection (BFD) provides fast link fault detection for BGP. BGP periodically sends messages to the peer to detect the status of the peer. The detection, however, lasts more than one second. When the data transmission rate reaches the level of Gbit/s, such a slow detection will cause a large amount of data to be lost. As a result, the requirement for high reliability of carrier-class networks cannot be met.
Therefore, BFD for BGP is introduced to fast detect faults on the links between BGP peers in milliseconds and notify the faults to BGP. Therefore, BGP routes can fast converge.
BFD for BGP is applicable to both IPv4 and IPv6 networks.
Networking
As shown in Figure 1, FW_A belongs to AS 10 and FW_B belongs to AS 20. FW_A and FW_B are directly connected, and the EBGP peer relationship is established between them.
BFD is enabled to detect the BGP relationship between FW_A and FW_B. When the link between FW_A and FW_B becomes faulty, BFD can fast detect the fault and notify it to BGP.
