Reference Guide

The sample configuration shows alternative ways to establish a BFD session with a BGP neighbor:
• By establishing BFD sessions with BGP discovering all neighbors (the bfd all-neighbors
command).
• By establishing a BFD session with a specified 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 notifies BGP of any failure conditions that it detects on the link. BGP initiates recovery actions.
BFD for BGP is supported only on directly-connected BGP neighbors and only in BGP IPv4 networks. On
the S5000, up to 128 simultaneous BFD sessions are supported
As long as each BFD for BGP neighbor receives a BFD control packet within the configured 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 use 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 configure BFD for BGP on the following types of interfaces: physical port (10GE or 40GE), port
channel, and VLAN.
1. Enable BFD globally.
CONFIGURATION mode
bfd enable
2. Specify the AS number and enter ROUTER BGP configuration mode.
CONFIGURATION mode
router bgp as-number
3. Add a BGP neighbor or peer group in a remote AS.
CONFIG-ROUTERBGP mode
neighbor {ip-address | peer-group name} remote-as as-number
4. Enable the BGP neighbor.
CONFIG-ROUTERBGP mode
neighbor {ip-address | peer-group-name} no shutdown
5. Configure parameters for a BFD session established with BGP discovering all neighbors. OR Establish
a BFD session with a specified BGP neighbor or peer group using the default BFD session parameters.
CONFIG-ROUTERBGP mode
bfd all-neighbors [interval millisecs min_rx millisecs multiplier value role
{active | passive}]
OR
Bidirectional Forwarding Detection (BFD)
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