(Optional) Configuring BFD for PW

BFD for PW helps quickly detect faults on public network links.

Context

On an MPLS L2VPN, if PWs exist between PEs, you can configure BFD for PW for rapid link fault detection, so that upper-layer applications can quickly switch to another link when a link experiences a fault.

A BFD session can be either static or dynamic. Determine which one to use as needed.

Procedure

Configure a static BFD session.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally, and the global BFD view is displayed.
3. Run quit
  The system view is displayed.
4. Run bfd bfd-name bind pw interface { interface-name1 | interface-type1 interface-number1 [ remote-peer remote-peer-address pw-ttl { auto-calculate | ttl-number } ] [ select-board slot-id | track-interface [ interface { interface-name1 | interface-type2 interface-number2 } ] ] [ secondary ]
  BFD configuration items are created.
  - Configure a BFD session to track a service PW.
    - The interface specified by interface interface-type1 interface-number1 is the AC interface on which the PW resides.
    - After track-interface is configured, the BFD session enters the Down state when the AC interface goes Down.
    - interface-type2 interface-number2 cannot be used to specify the type or number of an associated interface.
  - Configure a BFD session to track an mPW:
    - The interface specified by interface interface-type1 interface-number1 is the loopback interface.
    - track-interface interface-type2 interface-number2 can be used to specify the type and number of an associated interface. When the specified interface goes Down, the BFD session enters the Down state.
  If the PW to be detected is a secondary PW, be sure to configure secondary.
  
  The PW to be detected can be either an SS-PW or an MS-PW.
5. Configure BFD session discriminators.
  - Run discriminator local discr-value
    
    A local BFD session discriminator is configured.
  - Run discriminator remote discr-value
    
    A remote BFD session discriminator is configured.
  The local BFD session discriminator on one end must be the same as the remote BFD session discriminator on the other end.
6. Run commit
  The configuration is committed.
  
  If the status of a PW is Down, the BFD session can be established but cannot go Up.
  - BFD for PW must be configured or deleted on both endpoint PEs. Otherwise, the PW status may be inconsistent on the endpoint PEs.
  - To modify BFD session parameters after creating a BFD session, run the min-tx-interval, min-rx-interval, and detect-multiplier commands as required.
Configure a dynamic BFD session.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally, and the global BFD view is displayed.
3. Run quit
  The system view is displayed.
4. Adjust BFD detection parameters.
  1. Run pw-template pw-template-name
    
    The PW template view is displayed.
  2. Run control-word
    
    The control word function is enabled.
  3. Run bfd-detect [ detect-multiplier multiplier | min-rx-interval rx-interval | min-tx-interval tx-interval ] ^*
    
    BFD detection parameters are configured.
    The parameters are described as follows:
    detect-multiplier multiplier indicates the BFD detection multiplier.
    
    min-rx-interval rx-interval indicates the Required Min Rx Interval (RMRI), which is the supported minimum interval at which the local device receives BFD control packets.
    
    min-tx-interval tx-interval indicates the Desired Min Tx Interval (DMTI), which is the desired minimum interval at which the local device sends BFD control packets.
    
    The BFD detection parameters actually used may be different from the ones configured:
    Actual local detection interval = Actual interval at which the local device receives BFD packets x Configured remote BFD detection multiplier
    
    Actual interval at which the local device receives BFD packets = Max { Configured remote DMTI, Configured local RMRI }
    
    Actual interval at which the local device transmits BFD packets = Max { Configured local DMTI, Configured remote RMRI }
  4. Run quit
    
    The system view is displayed.
5. Trigger the establishment of a dynamic BFD session.
  1. Run interface interface-type interface-number
    
    The AC interface view is displayed.
  2. Run mpls l2vpn pw bfd [ detect-multiplier multiplier | min-rx-interval rx-interval | min-tx-interval tx-interval ] ^* [ remote-vcid vc-id ] [ track-interface ] [ secondary ]
    
    Dynamic BFD for PW is enabled to trigger the establishment of a dynamic BFD session to detect the VPWS PW connectivity.
    
    If the PW to be detected is a secondary PW, be sure to configure secondary.
6. Run commit
  The configuration is committed.