IGMP Configuration Task List 617Enhancements in query and report capabilities1 Query message carrying the source addressesIGMPv3 supports not only general queries (feature of IGMPv1) and group-specificqueries (feature of IGMPv2), but also group-and-source-specific queries.■ A general query does not carry a group address, nor a source address;■ A group-specific query carries a group address, but no source address;■ A group-and-source-specific query carries a group address and one or moresource addresses.2 Reports containing multiple group recordsUnlike an IGMPv1 or IGMPv2 report message, an IGMPv3 report message isdestined to 224.0.0.22 and contains one or more group records. Each grouprecord contains a multicast group address and a multicast source address list.Group record types include:■ IS_IN: The source filtering mode is Include, namely, the report sender requeststhe multicast data from only the sources defined in the specified multicastsource list. If the specified multicast source list is empty, this means that thereport sender has left the reported multicast group.■ IS_EX: The source filtering mode is Exclude, namely, the report sender requeststhe multicast data from any sources but those defined in the specified multicastsource list.■ TO_IN: The filter mode has changed from Exclude to Include.■ TO_EX: The filter mode has changed from Include to Exclude.■ ALLOW: The Source Address fields in this Group Record contain a list of theadditional sources that the system wishes to hear from, for packets sent to thespecified multicast address. If the change was to an Include source list, theseare the addresses that were added to the list; if the change was to an Excludesource list, these are the addresses that were deleted from the list.■ BLOCK: indicates that the Source Address fields in this Group Record contain alist of the sources that the system no longer wishes to hear from, for packetssent to the specified multicast address. If the change was to an Include sourcelist, these are the addresses that were deleted from the list; if the change wasto an Exclude source list, these are the addresses that were added to the list.Protocols and Standards The following documents describe different IGMP versions:■ RFC 1112: Host Extensions for IP Multicasting■ RFC 2236: Internet Group Management Protocol, Version 2■ RFC 3376: Internet Group Management Protocol, Version 3IGMP ConfigurationTask ListComplete these tasks to configure IGMP:
