What IETF working groups deal with multicast ?
There are quite a number : Audio Video Transport or AVT, deals with streaming audio, video and multimedia using the Real Time Protocol (RTP). Reliable Multicast Transport or RMT, deals with reliable transport proposals. PIM deals with the Protocol Independent Multicast specification. MBONED deals with issues of MBone deployment, and tends to have the most discussion about operational multicast issues. MAGMA is responsible for IGMP v3 and MLD v2 (and IDMR was phased out). There is a also an IETF Working Group on Multicast Security.