PIM Flooding Mechanism (PFM) and Source Discovery (SD)

Protocol Independent Multicast - Sparse Mode (PIM-SM) uses a Rendezvous Point (RP) and shared trees to forward multicast packets from new sources. Once Last-Hop Routers (LHRs) receive packets from a new source, they may join the Shortest Path Tree (SPT) for the source for optimal forwarding. This document defines a new mechanism that provides a way to support PIM-SM without the need for PIM registers, RPs, or shared trees. Multicast source information is flooded throughout the multicast domain using a new generic PIM Flooding Mechanism (PFM). This allows LHRs to learn about new sources without receiving initial data packets.