Configuring BFD for VPWS PW

Configuring BFD for VPWS PW accelerates PW fault detection, resulting in fast switching of upper-layer applications.

Usage Scenario

When PEs on an MPLS L2VPN are connected over PWs, configuring BFD to detect PW connectivity accelerates PW fault detection.

A BFD session can be static or dynamic. Select one as needed.

Pre-configuration Tasks

Before configuring BFD for VPWS PW, complete the following tasks:

Configure network layer parameters for devices on the MPLS L2VPN to communicate.
Configure PWs.
If interworking with non-Huawei devices is required, run the mpls l2vpn vccv bfd-cv-negotiation command to change the BFD CV Type in Label Mapping packets to be the same as that on the remote peer.
Static BFD for VLL PW does not support a CV type of 0x10 or 0x20 in control word mode. If the CV type in the PW negotiation result is 0x10 or 0x20, the BFD session cannot go Up.

Procedure

Configure a static BFD session.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally, and the BFD view is displayed.
3. Run quit
  Return to the system view.
4. Run bfd cfg-name bind pw interface interface-type1 interface-number1 [ remote-peer remote-peer-address pw-ttl { auto-calculate | ttl-number } ] [ select-board slot-id | track-interface [ { interface | controller } interface-type2 interface-number2 ] ] [ secondary ]
  - Create a BFD session for VPWS PW.
    
    Run bfd session-name bind pw interface interface-type1 interface-number1 [ remote-peer remote-peer-address pw-ttl { auto-calculate | ttl-number } ] [ select-board slot-id | track-interface [ { interface } interface-type2 interface-number2 ] ] [ secondary ]
    
    BFD configuration items are created.
  A BFD configuration item is created.
  - When the BFD session is used to monitor a service PW:
    - The interface specified by the interface interface-type1 interface-number1 parameter is the AC interface on which the PW resides.
    - The track-interface parameter can be configured. When the AC interface goes Down, the BFD session enters the Down state.
    - You cannot use the interface-type2 interface-number2 parameter to specify the type and number of an associated interface.
  - When the BFD session is used to monitor a management PW:
    - The interface specified by the interface interface-type1 interface-number1 parameter is the loopback interface.
    - You can use the track-interface interface-type2 interface-number2 parameter 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, you must specify secondary.
  
  The PW to be detected can be either an SS-PW or an MS-PW.
5. Configure 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 remote BFD session discriminator on the other end.
6. Run commit
  The configuration is committed.
  
  If the PW to be detected is Down, the BFD session can be established but cannot go Up.
  - You must configure or cancel BFD for PW on both ends of a PW. Otherwise, the PW status on both ends may be inconsistent.
  - If you want to modify the parameters of an existing BFD session, run corresponding commands, such as min-tx-interval, min-rx-interval, and detect-multiplier.
Configure a dynamic BFD session.
1. Run system-view
  The system view is displayed.
2. Run bfd
  BFD is enabled globally, and the BFD view is displayed.
3. Run quit
  Return to the system view.
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.
    BFD detection parameters are 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
    Return to the system view.
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, you must specify secondary.
6. Run commit
  The configuration is committed.

Checking the Configurations

After configuring BFD for VPWS PW, check the configurations.

Run the display bfd session command to check BFD session configurations.
Run the display mpls l2vc interface interface-type interface-number command to check dynamic BFD session configurations.