TCP/IP Tutorial and Technical Overview - IBM Redbooks

In Figure 6-4 on page 245, the Type, Checksum, and Number of Group Records
fields are equivalent to their IGMPv3 message query counterparts. However, in
the membership report message, each Group Record is broken up, as illustrated
in Figure 6-5.
Figure 6-5 IGMPv3 group record
The fields within the group record are described as follows:
► Record Type: This field indicates whether the group record type is a
current-state, filter-mode-change, or source-list-change record. The values
are as follows:
– Current-state records are sent by a system in response to a query
received on an interface, and report the current reception of that interface.
There are two group record values that denote a current-state record:
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Record Type
Reserved
Multicast Address
Source Address [1]
Source Address [2]
. . .
Source Address [N]
Auxiliary Data
Number of Sources (N)
MODE_IS_INCLUDE: This indicates that the interface has a filter mode
of INCLUDE for the specified multicast addresses.
MODE_IS_EXCLUDE: This indicates that the interface has a filter
mode of EXCLUDE for the specified multicast addresses.