Configuring BFD for an IS-IS Process

Procedure

1. Run system-view

   The system view is displayed.

2. Run isis process-id

   The IS-IS view is displayed.

3. (Optional) Run bfd session-up check

   BFD session check is configured for the IS-IS process.

   

   When the Layer 2 network is running normally, IS-IS neighbor relationships can be established and routes can be delivered. However, if the Layer 3 network is unreachable, upper-layer traffic loss occurs. To resolve this problem, configure BFD session check for an IS-IS process by running the bfd session-up check command. This ensures that an IS-IS neighbor relationship is established only when the BFD session is up on corresponding interfaces. After this function is configured, it applies only to the neighbor relationships to be established (it does not apply to existing neighbor relationships).

4. Run bfd all-interfaces enable

   BFD is enabled for an IS-IS process to establish BFD sessions.

   BFD must be enabled globally before you perform this step. If BFD is enabled globally, this step is performed, and the status of neighbors is up (or the DIS is up in the case of a broadcast network), default BFD parameters are used by all interfaces in the IS-IS process to establish BFD sessions.

5. (Optional) Run bfd all-interfaces { min-rx-interval receive-interval | min-tx-interval transmit-interval | detect-multiplier multiplier-value | frr-binding | tos-exp tosexp-value } ^*

   The parameters for establishing a BFD session are set.

   Configure the parameters based on the actual network environment. If the time parameters are set improperly, network flapping may occur.

   BFD detection intervals are calculated as follows:

   • Effective local interval at which BFD packets are sent = MAX { Configured local interval at which BFD packets are sent, Configured remote interval at which BFD packets are received }
   • Effective local interval at which BFD packets are received = MAX { Configured remote interval at which BFD packets are sent, Configured local interval at which BFD packets are received }
   • Effective local detection interval = Effective local interval at which BFD packets are received x Configured remote detection multiplier

   If tos-exp tosexp-value is specified, a priority is configured for all IS-IS BFD packets of the current process.

6. (Optional) Run bfd all-interfaces incr-cost { cost-value | max-reachable }

   The IS-IS process is enabled to adjust its cost based on the status of an associated BFD session.

   Regarding the configuration of adjusting the interface cost based on the status of an associated BFD session, the configuration in the interface view takes precedence over that in the IS-IS view.

7. Run commit

   The configuration is committed.