| 摘要 |
Alternate multicast/broadcast paths may be calculated in a routed network to enable broadcast/multicast traffic to be transmitted around a local failure in the routed network until the routing system reconverges on a new network topography. According to an embodiment of the invention, the nodes on a multicast tree or a broadcast tree may compute alternate paths for each of the downstream nodes in the multicast/broadcast tree or for select nodes in the multicast/broadcast tree. The select nodes may be those nodes that have advertised membership in the multicast or a set number of hops downstream on the branch affected by the failure. The alternate paths may be unicast paths from the node to the other nodes on the multicast/broadcast tree. U-turn nodes may be used where there is no regular loop-free alternate network path to a node on the downstream multicast/broadcast tree.
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