IGMPv1 is defined by RFC 1112, IGMPv2 is defined by RFC 2236 and IGMPv3 was initially defined by RFC 3376 and has been updated by RFC 4604 which defines both IGMPv3 and MLDv2.
IGMPv1 определен в RFC 1112, IGMPv2 — в RFC 2236 и IGMPv3 — в RFC 3376.