Patent ID: 7656792
Filing Date: 2010-02-02
Classification: H04L

Abstract:
1. A method of circumventing a local failure on a multicast tree in a link state protocol controlled network in which nodes on the network forward unicast traffic using shortest path forwarding and in which the nodes on the network forward multicast traffic along links included in the multicast tree, the method comprising the steps of: determining, by an intermediate node in the multicast tree, a set of downstream nodes on at least one branch of the multicast tree that passes through the intermediate node; and calculating a set of loop free neighboring nodes that have shortest paths to the set of downstream nodes that do not pass through the intermediate node; encapsulating multicast traffic with a unicast header for each of the set of downstream nodes; and forwarding the encapsulated multicast traffic to the set of loop free neighboring nodes to enable the loop free neighboring nodes to forwarding the encapsulated multicast traffic using their shortest path forwarding state toward the set of downstream nodes.