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Understanding Static Route State When BFD is in Admin Down State

The Bidirectional Forwarding Detection (BFD) Admin Down state is used to bring down a BFD session administratively (applicable for normal BFD session and micro BFD session), to protect client applications from BFD configuration removal, license issues, and clearing of BFD sessions.

When BFD enters the Admin Down state, BFD notifies the new state to its peer for a failure detection time and after the time expires, the client stops transmitting packets.

For the Admin Down state to work, the peer, which receives the Admin Down state notification, must have the capability to distinguish between administratively down state and real link failure.

A BFD session moves to the Admin Down state under the following conditions:

  • If BFD configuration is removed for the last client tied to a BFD session, BFD moves to Admin Down state and communicates the change to the peer, to enable the client protocols without going down.

  • If BFD license is removed on the client, BFD moves to Admin Down state and communicates the change to the remote system to enable the client protocols without going down.

  • When clear bfd session command is executed, the BFD sessions move to Admin Down state before restarting. This clear bfd session command also ensures that the client applications are not impacted.

Starting from Junos OS 16.1R1 release, you can set the state of static route in BFD Admin Down state by configuring one of the following commands:

  • set routing-options static static-route bfd-admin-down active—BFD Admin Down state pulls down the static route.

  • set routing-options static static-route bfd-admin-down passive—BFD Admin Down state does not pull down the static route.