FGCP Supports BFD Enabled BGP Graceful Restart After an HA Failover

FGCP supports BFD enabled BGP graceful restart after an HA failover

If an HA cluster is part of a Border Gateway Protocol (BGP) bidirectional forwarding detection (BFD) configuration where both the cluster and the BGP static neighbor are configured for graceful restart, after an HA failover BGP enters graceful restart mode and both the cluster and the BGP neighbor keep their BGP routes.

To support HA and BFD enabled BGP graceful:

  • From the cluster, configure the BFD enabled BGP neighbor as a static BFD neighbor using the config router bfd command.Set the BGP auto-start timer to 5 seconds so that after an HA failover BGP on the new primary unit waits for 5 seconds before connect to its BFD neighbors, and then registers BFD requests after establishing the connections. With static BFD neighbors, BFD requests and sessions can be created as soon as possible after the failover.The command get router info bfd requests shows the BFD peer requests.
  • The BFD session created for a static BFD neighbor/peer request initializes its state as INIT instead of DOWN and its detection time as bfd-required-min-rx * bfd-detect-mult msecs.
  • When a BFD control packet with a nonzero Your Discriminator (your_discr) value is received, if no session can be found to match the your_discr, instead of discarding the packet, other fields in the packet, such as addressing information, are used to choose one session that was just initialized, with zero as its remote discriminator.
  • When a BFD session in the UP state receives a control packet with zero as Your Discriminator and DOWN as State, the session changes its state to DOWN but will not notify this DOWN event to BGP and/or other registered clients.

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