IGMP Configuration Task List 617
Enhancements in query and report capabilities
1 Query message carrying the source addresses
IGMPv3 supports not only general queries (feature of IGMPv1) and group-specific
queries (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 more
source addresses.
2 Reports containing multiple group records
Unlike an IGMPv1 or IGMPv2 report message, an IGMPv3 report message is
destined to 224.0.0.22 and contains one or more group records. Each group
record 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 requests
the multicast data from only the sources defined in the specified multicast
source list. If the specified multicast source list is empty, this means that the
report sender has left the reported multicast group.
■ IS_EX: The source filtering mode is Exclude, namely, the report sender requests
the multicast data from any sources but those defined in the specified multicast
source 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 the
additional sources that the system wishes to hear from, for packets sent to the
specified multicast address. If the change was to an Include source list, these
are the addresses that were added to the list; if the change was to an Exclude
source list, these are the addresses that were deleted from the list.
■ BLOCK: indicates that the Source Address fields in this Group Record contain a
list of the sources that the system no longer wishes to hear from, for packets
sent to the specified multicast address. If the change was to an Include source
list, these are the addresses that were deleted from the list; if the change was
to 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 3
IGMP Configuration
Task List
Complete these tasks to configure IGMP:
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