Techniques are described for establishing a point-to-multipoint (P2MP) label switched path (LSP) using a branch node-initiated signaling model in which branch node to leaf (B2L) sub-LSPs are signaled and utilized to form a P2MP LSP. The techniques described herein provides a scalable solution in which the number of sub-LSPs for which the source node or any given branch node need maintain state is equal to the number of physical data flows output from that node to downstream nodes, i.e., the number of output interfaces used for the P2MP LSP by that node to output data flows to downstream nodes. As such, unlike the conventional source node-initiated model in which each node maintains state for sub-LSPs that service each of the leaf nodes downstream from the device, the size and scalability of a P2MP LSP is no longer bound to the number of leaves that are downstream from that node.