HP VPN Firewall Appliances Appendix Protocol Reference

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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 records include the following categories:
{ IS_IN—The source filtering mode is Include. The report sender requests the multicast data from
only the sources defined in the specified multicast source list.
{ IS_EX—The source filtering mode is Exclude. The report sender requests the multicast data from
any sources but those defined in the specified multicast source list.
{ TO_IN—The filtering mode has changed from Exclude to Include.
{ TO_EX—The filtering 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 wants to obtain data from, for packets sent to the specified multicast address. If
the change was to an Include source list, these sources are the addresses that were added to the
list. If the change was to an Exclude source list, these sources are the addresses that were
deleted from the list.
{ BLOCK—The Source Address fields in this group record contain a list of the sources that the
system no longer wants to obtain data from, for packets sent to the specified multicast address.
If the change was to an Include source list, these sources are the addresses that were deleted
from the list. If the change was to an Exclude source list, these sources are the addresses that
were added to the list.
IGMP SSM mapping
The IGMP SSM mapping feature enables you to configure static IGMP SSM mappings on the last-hop
router to provide SSM support for receiver hosts that are running IGMPv1 or IGMPv2. The SSM model
assumes that the last-hop router has identified the desired multicast sources when receivers join multicast
groups.
• When a host that is running IGMPv3 joins a multicast group, it can explicitly specify one or more
multicast sources in its IGMPv3 report.
• A host that is running IGMPv1 or IGMPv2, however, cannot specify multicast source addresses in its
report. In this case, you must configure the IGMP SSM mapping feature to translate the (*, G)
information in the IGMPv1 or IGMPv2 report into (G, INCLUDE, (S1, S2...)) information.