(Optional) Configuring an mPW

Context

If there are multiple service PWs, configure BFD for mPW and associate these service PWs with the mPW to reduce the number of BFD sessions and save public network bandwidth. In this way, BFD monitors service PWs by detecting the mPW. Generally, an mPW is configured on the primary PW path but not the secondary PW path.

Figure 1 and Figure 2 show PW redundancy scenarios where CEs are asymmetrically connected to PEs. Assume that the PW between PE1 and PE2 is the primary PW.

Figure 1 Networking diagram of PW redundancy in the scenario where CEs are asymmetrically connected to PEs (single-hop PWs)

Figure 2 Networking diagram of PW redundancy in the scenario where CEs are asymmetrically connected to PEs (multi-hop PWs)

Procedure

Perform the following operations on PE1 and PE2.
1. Run system-view
  The system view is displayed.
2. Run interface loopback interface-number
  The loopback interface view is displayed.
  
  An mPW can be configured only in the loopback interface view where no IP address is configured.
3. Run mpls l2vc { ip-address | pw-template pw-template-name } ^* vc-id [ tunnel-policy policy-name | control-word ] ^* admin
  An mPW is configured.
  - When creating a PW, specify the IP address and VC ID of the destination PE. The VC IDs of devices at both ends of the VC must be the same.
  - The default tunnel policy for a dynamic PW uses the LDP tunnel, and only one LDP is used for load balancing. To use another tunnel type, specify tunnel-policy policy-name to import the desired tunnel policy.
  - To configure BFD for PW to rapidly detect faults in public network links, configure control-word to enable the control word function on an mPW because BFD control packets are encapsulated in PW control packets.
  - The encapsulation type of an mPW is ip-interworking.
(Optional) Perform the following operations on SPE1 if the service PW is a multi-hop PW.
1. Run system-view
  The system view is displayed.
2. Run mpls switch-l2vc ip-address vc-id [ tunnel-policy policy-name ] between ip-address vc-id [ tunnel-policy policy-name ] encapsulation ip-interworking [ control-word-transparent ]
  A switching PW of the mPW is configured.
  - The PW ID and PW type of a node must be unique. The PW IDs of devices at both sides of the switching PW, however, can be the same.
  - The encapsulation type is set to ip-interworking when an mPW is configured on a loopback interface. Accordingly, the encapsulation type must be set to ip-interworking when a switching PW is configured.
  - control-word-transparent indicates that the control word transparent transmission function must be configured on the SPE before configuring BFD to detect PWs. Otherwise, the BFD session cannot be established.