This chapter contains configuration for Pseudowire Redundancy with MLAG (Active and Standby). It also provides an overview of Pseudowire concepts.

In a single-segment pseudowire (SS-PW) application, the Packet Switched Network (PSN) layer usually provides protection for the PW. One way is by using an RSVP LSP with Fast Reroute (FRR) backup; another way is an end-to-end backup LSP. However, there are some applications where the backup PW terminates on a different target PE node, so PSN protection methods cannot protect against failure of either the target Provider Edge (PE) node or a remote Access Circuit (AC). It is also important for an operator that a particular PW is preferred. For example, the one with the least latency.

PW redundancy supports Label Distribution Protocol (LDP) PW. In the case of PW applications, the PSN layer can provide the protection for PW. Occasionally, a TE LSP signaled by RSVP-TE can be used as a PSN tunnel for a PW. In this scenario, TE can provide FRR to protect the end-to-end LSP in the PSN layer.

FRR-based protection schemes cannot protect against failure of PE nodes and access circuits. However, PW redundancy can protect against these failures.

MLAG expands the concept of link aggregation so that it provides node-level redundancy by allowing two nodes to share a common LAG endpoint. This gives PE redundancy for CE node.

CE devices can be connected to two PE nodes for PE-node-level redundancy using MLAG.

End-to-End traffic flow decision will take by MLAG Active node not by PW-Redundancy node.