This feature allows a downstream LSR of a multicast LDP (mLDP) FEC to perform a fast switchover to source the traffic from another upstream LSR while IGP and LDP are converging because of a failure of the upstream LSR, where the upstream LSR is the primary next hop of the root LSR for the point-to-multipoint FEC. The feature is enabled using the mcast-upstream-frr command.
The feature provides upstream fast reroute (FRR) node protection for mLDP FEC packets. The protection is at the expense of traffic duplication from two different upstream nodes into the node that performs the fast upstream switchover.
The detailed procedures for this feature are described in draft-pdutta-mpls-mldp-up-redundancy.