IP addresses in the 232/8 (232.0.0.0 to 232.255.255.255) range are designated as source-specific multicast (SSM) destination addresses and are reserved for use by source-specific applications and protocols [IANA-ALLOCATION]. This document defines the semantics of source- specific multicast addresses and specifies the policies governing their use. It defines an extension to the Internet network service that applies to datagrams sent to SSM addresses and defines the host extensions to support this service. Appendix I of this document describes changes to the Internet Group Management Protocol Version 3 (IGMPv3) [IGMPv3] to support source- specific multicast.