Patent ID: 7570649

Claim:
A method of establishing a tunneling Multi-Protocol Label Switched Path (LSP) between nodes in a multicast network, the method comprising: receiving an instruction to establish a first path from a source node in a first multicast tree to a destination node in the first multicast tree, the first path including a connection between a branching node and a next hop branching node; establishing an LSP extending from the branching node to the next hop branching node by performing the following steps: determining a next hop toward the next hop branching node, wherein the next hop is an intermediate node between the branching node and the next hop branching node, sending an LSP path request to the next hop, receiving the request at the next hop, selecting an ingress label for the LSP at the next hop wherein the ingress label is selected by performing the following steps: when a second LSP terminating at the next hop branching node and traveling through the next hop exists, selecting a previously assigned ingress label for the second LSP as the ingress label, and when a second LSP terminating at the next hop branching node and traveling through the next hop does not exist, selecting an unused ingress label as the ingress label, and sending a reply from the next hop, the reply specifying the ingress label and the identification of the next hop branching node; storing, at the branching node, tunneling information regarding the LSP, the tunneling information including an identification of the next hop branching node; receiving an instruction to establish a second path from a source node in a second multicast tree to a destination node in the second multicast tree; determining whether the second path shares the connection between the branching node and the next hop branching node using the identification of the next hop branching node included in the tunneling information; and when it is determined that the second path shares the connection between the branching node and the next hop branching node, using the LSP as part of the second path, whereby forwarding states are shared between the first multicast tree and the second multicast tree.