Concept Guide
Figure 13. Establishing Sessions with BGP Neighbors
The sample conguration shows alternative ways to establish a BFD session with a BGP neighbor:
• By establishing BFD sessions with all neighbors discovered by BGP (the bfd all-neighbors command).
• By establishing a BFD session with a specied BGP neighbor (the neighbor {ip-address | peer-group-name} bfd
command)
BFD packets originating from a router are assigned to the highest priority egress queue to minimize transmission delays. Incoming BFD
control packets received from the BGP neighbor are assigned to the highest priority queue within the control plane policing (CoPP)
framework to avoid BFD packets drops due to queue congestion.
BFD noties BGP of any failure conditions that it detects on the link. Recovery actions are initiated by BGP.
BFD for BGP is supported only on directly-connected BGP neighbors and only in BGP IPv4 networks.
As long as each BFD for BGP neighbor receives a BFD control packet within the congured BFD interval for failure detection, the BFD
session remains up and BGP maintains its adjacencies. If a BFD for BGP neighbor does not receive a control packet within the detection
interval, the router informs any clients of the BFD session (other routing protocols) about the failure. It then depends on the individual
routing protocols that uses the BGP link to determine the appropriate response to the failure condition. The typical response is to terminate
the peering session for the routing protocol and reconverge by bypassing the failed neighboring router. A log message is generated
whenever BFD detects a failure condition.
You can congure BFD for BGP on the following types of interfaces: physical port (10GE or 40GE), port channel, and VLAN.
1 Enable BFD globally.
CONFIGURATION mode
Bidirectional Forwarding Detection (BFD)
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