Static S-BFD discriminator configuration

To statically map a Seamless BFD remote IP address with its discriminator, use the following CLI commands:

config>router>bfd
   seamless-bfd
      peer <ip-address> discriminator <remote-discriminator>
      peer <ip-address> discriminator <remote-discriminator>
      ...
      exit

The S-BFD initiator immediately starts sending S-BFD packets if the discriminator value of the far-end reflector is known, no session setup is required.

With S-BFD sessions, there is no INIT state. The initiator state changes from AdminDown to Up when it begins to send (initiate) S-BFD packets.

The S-BFD initiator sends the BFD packet to the reflector using the following fields:

Src IP

This field contains the local session IP address. For IPv6, this is a global unicast address belonging to the node.

Dst IP

This field contains the reflector's IP address (configured).

MyDiscriminator

This field contains the locally assigned discriminator.

YourDiscriminator

This field contains the reflector's discriminator value.

If the initiator receives a valid response from the reflector with an Up state, the initiator declares the S-BFD session state as Up.

If the initiator fails to receive a specific number of responses, as determined by the BFD multiplier in the BFD template for the session, the initiator declares the S-BFD session state as Failed.

If any of the discriminators change, the session fails and the router attempts to restart with the new values. If the reflector discriminator changes at the far-end peer, the session fails, but the mapping may not have been updated locally before the system checks for a new reflector discriminator from the local mapping table. The session is bounced, bringing it up with the new values. If any discriminator is deleted, the corresponding S-BFD sessions are deleted.