Host extensions for IP multicasting

This memo specifies the extensions required of a host implementation of the Internet Protocol (IP) to support multicasting. IP multicasting is the transmission of an IP datagram to a "host group", a set hosts identified by a single IP destination address. A multicast datagram is delivered to all members of its destination host group with the same "best-efforts" reliability as regular unicast IP datagrams. It is proposed as a standard for IP multicasting in the Internet. This specification is a major revision of RFC-988.