Bidirectional Forwarding Detection (BFD) for BGP

Bidirectional Forwarding Detection (BFD) protection of BGP peering sessions allows for the rapid detection of link failures such that peering sessions can be taken out of the "established" state within fractions of a second. This allows the protocol to select an alternate path (if available) to a destination immediately after the link failure, rather than waiting until the BGP hold timer expires (180 seconds by default).

This feature applies to both IPv4 and IPv6 peering sessions. Both IPv6 global and link local peering sessions are supported.

Multi-hop BFD is introduced in ExtremeXOS 30.5. This enhancement allows BFD support for non-directly connected EBGP sessions, as well as IBGP sessions. Multi-hop BFD is supported in hardware assist BFD also. There are no new BGP configuration or show commands associated with multi-hop BFD. However, the show bfd session {ipv4 | ipv6} {ipaddress } detail {vr [vrname | all]} command shows "Session Type" as "Multi Hop" for multi-hop BFD and "Single Hop" for single-hop BFD.