Source-Specific Multicast

Using the Any-Source Multicast (ASM) service model, sources and receivers register with a multicast address. The protocol uses regular messages to maintain a correctly configured broadcast network where all sources can send data to all receivers and all receivers get broadcasts from all sources.

With Source-Specific Multicast (SSM), the "channel" concept is introduced where a "channel" consists of a single source and multiple receivers who specifically register to get broadcasts from that source. Consequently, receivers are not burdened with receiving data they have no interest in, and network bandwidth requirements are reduced because the broadcast need only go to a sub-set of users. The address range 232/8 has been assigned by the Internet Assigned Numbers Authority (IANA) for use with SSM.