Patent ID: 8050264

Claim:
A method for re-routing a multicast stream when a unicast route to a multicast source or a rendezvous point changes from a first route to a second route, wherein the first route is corresponding to a prior multicast forwarding path between a first upstream router and a downstream router, the second route is corresponding to a new multicast forwarding path between a second upstream router and the downstream router, a multicast stream is forwarded via the prior multicast forwarding path, the method comprising: establishing the new multicast forwarding path between the downstream router and the second upstream router; keeping receiving said multicast stream from the first upstream router via a first incoming interface corresponding to said prior multicast forwarding path and forwarding the multicast stream via said prior multicast forwarding path before the multicast stream forwarded via the new multicast forwarding path is received by the downstream router; and pruning said prior multicast forwarding path once the multicast stream forwarded via the new multicast forwarding path is received by said downstream router.