What are the functions and typical scenarios of the association between BFD session status and interface status

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For S series switches, you can run the process-interface-status command in the BFD session view to enable the association between the BFD status and the interface status. When the BFD session status changes, run the display this interface command in the interface view. If the command output shows that Line protocol current state is UP (BFD Status Down), the routing management module withdraws the host routes and network segment routes on the interface.

Application scenario: The association between the BFD status and the interface status are often used when a Layer 2 device or data transmission device exists between two Layer 3 devices, or when a single fiber failure occurs.

Other related questions:
What are the functions and typical scenarios of BFD and interface status association
Using the process-interface-status command in the BFD session view, you can enable interface status association. When the BFD session status changes, the Line protocol current state is Up (BFD Status Down) when you run the display this interface command on the interface. At the same time, the RM withdraws the host routes and network segment routes on the interface. Application scenario: BFD for IFNET is usually applied to the scenario where a Layer 2 device exists between two routers, or there are transmission devices, or a single fiber fault occurs.

Why can association between BFD session status and interface status on S series switches be used only on multicast BFD sessions
For S series switches, a multicast BFD session uses multicast packets and is not affected by the protocol status on an interface. When the BFD session goes Down and the protocol status on the interface changes to BFDSatusDown, multicast BFD packets can still be sent. After the link recovers, the multicast BFD session becomes Up after negotiation. As a result, the interface is unlocked and becomes Up. Unicast packets, however, cannot be sent or received after the protocol status on the interface goes Down, which causes deadlock.

Configure association between VRRP and the interface status for S series switches
Association between VRRP and the interface status can be configured on S series switches (S1700 excluded). VRRP uplink interface tracing can be configured to ensure that the master priority is reduced when the tracked interface is faulty. A VRRP master/backup switchover is then triggered to switch links and minimize the impact of interface faults on service forwarding. The configuration method is as follows: Run the interface interface-type interface-number command to enter the interface view where the VRRP group resides on the master device. 2. Run the vrrp vrid virtual-router-id track interface interface-type interface-number [ increased value-increased | reduced value-reduced ] command to associate the VRRP group with the interface status for uplink interface tracing. It should be noticed that when association between the VRRP group and the interface status is configured, master and backup devices in the VRRP group must work in preemption mode. It is recommended that you configure immediate preemption for the backup device and delayed preemption for the master device.

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