Students who want to read more about multicast can read:

RFC 1112 (IGMP version 1: Current Standard)
RFC 2236 (IGMP version 2: Proposed Standard only)

also (all related to multicast, not all on IGMP):

RFC 0922,
RFC 1075,
RFC 1301,
RFC 1458,
RFC 2908,
RFC 3208.

Doing an RFC search on ``Multicast'' gives quite a few more, but these 
seem to be the most important ones.