PIM Source-Specific Multicast (PIM-SSM)
PIM Source-Specific Multicast (PIM-SSM) – A PIM mode in which receivers join a specific (source, group) pair rather than any source for a group, building distribution trees rooted at the source; used when the source is known in advance, for a more efficient, scalable, and secure model. See: Multicast, Configure IP Multicast