US Patent 7940698 Point to multi-point label switched paths with label distribution protocol

The label distribution protocol (LDP) is extended to set up a point to multi-point (P2MP) label switched path (LSP) across a computer network from a source network device to one or more destination network devices. LDP is extended to create a P2MP label map message containing a label and a P2MP forwarding equivalence class (FEC) element having a root node address and an identifier. The P2MP FEC element may, for example, associate an address of the root node of the P2MP LSP with an opaque identifier. The P2MP FEC element uniquely identifies the P2MP LSP. The P2MP FEC element may be advertised with a label in a P2MP label map message. A source network device or the destination network devices may initiate setup and teardown of the P2MP LSP. The P2MP label map messages may be propagated from the destination network devices to the source network device.