PW redundancy

PW redundancy provides redundant links between PEs so that the customer networks can communicate when the path over one PW fails. As shown in Figure 68, PE 1 establishes two PWs (one primary and one backup). The CEs communicate through the primary PW. When the primary PW fails, PE 1 brings up the backup PW and forwards packets from CE 1 to CE 2 through the backup PW. When CE 2 receives the packets, it updates its MAC address table, so that packets from CE 2 to CE 1 also travel through the backup PW. Only static PWs and LDP PWs support PW redundancy.

Figure 68: PW redundancy

The MPLS L2VPN determines whether the primary PW fails according to the LDP session status or the BFD result. The backup PW is used when one of the following conditions exists: