MPLS Multicast Fast Reroute

In this chapter, we describe MPLS multicast Fast Reroute, a rerouting mechanism adapted to protect multicast routing trees from single link failures. MPLS multicast Fast Reroute extends the unicast MPLS Fast Reroute mechanism presented in Chapter 2. MPLS multicast Fast Reroute makes it possible to repair a multicast routing tree if a single link of the so-called protected path fails by rerouting traffic on a pre-planned backup path. This rerouting mechanism uses the same components as MPLS unicast Fast Reroute. A backup path must first be established in a multicast routing tree. Then, when a node detects a link failure or recovery, it sends a notification message to the Path Switching LERs (PSLs, see Section 2.4) that performs either switchover of switchback. MPLS multicast Fast Reroute assumes that multicast routing trees are core based trees.