PW redundancy is supported for static MPLS-TP pseudowires. However, instead of using T-LDP status signaling to signal the forwarding state of a PW, control channel status signaling is used.
The following PW redundancy scenarios must be supported:
MC-LAG and MC-APS with single and multi-segment PWs interconnecting the PEs.
MS-PW (S-PE) Redundancy between VLL PEs with single-homed CEs.
Dual-homing of a VLL service into redundant IES or VPRN PEs, with active/standby PWs.
Dual-homing of a VLL service into a VPLS with active/standby PWs.
Active/standby dual-homing into routed VPLS is not supported in for MPLS-TP PWs. This is because it relies on PW label withdrawal of the standby PW to take down the VPLS instance, and therefore the associated IP interface. Instead, it is possible to enable BGP multi-homing on a routed VPLS that has MPLS-TP PWs as spokes, and for the PW status of each spoke SDP to be driven (using control channel status) from the active or standby forwarding state assigned to each PW by BGP.
It is possible to configure inter-chassis backup (ICB) PWs as static MPLS-TP PWs with MPLS-TP identifiers. Only MPLS-TP PWs are supported in the same endpoint. That is, PWs in an endpoint must either be all MPLS-TP, or none of them must be MPLS-TP. This implies that an ICB used in an endpoint for which other PWs are MPLS TP must also be configured as an MPLS-TP PW.
A failover to a standby pseudowire is initiated based on the existing supported methods (for example, failure of the SDP).