SSM

Source Specific Multicast. Multicast using PIM-SSM for multicast stream routing (see RFC 3569) and IGMPv3 (see RFC 3376)to advertise and join streams. It allows a device to receive a multicast stream that has been sent to a particular multicast address from a specific source. It can pick out just that source even though multiple sources could be sending streams to that same multicast address.

See IGMP, PIM, Multicast