Protocol Independent Multicast – Sparse Mode (PIM-SM) protocol

A protocol for efficiently routing Internet Protocol (IP) packets to multicast groups that may span wide-area and inter-domain Internets. The protocol is called “protocol independent” because it is not dependent on any particular unicast routing protocol for topology discovery, and sparse-mode because it is suitable for groups where a very low percentage of the nodes (and their routers) will subscribe to the multicast session.