D-Link DES-3326S User Manual page 113

DES-3326S Layer 3 Fast Ethernet Switch User's Guide
the router should forward multicast packets it receives to the
subnetworks it is attached to or not. A multicast router that
has received a multicast packet will check to determine if there
is at least one member of a multicast group that has requested
to receive multicast packets from this source. If there is one
member, the packet is forwarded. If there are no members, the
packet is dropped.
IGMP Versions 1 and 2
Users that want to receive multicast packets need to be able to
join and leave multicast groups. This is accomplished using
IGMP.
The IGMP Type codes are shown below:
Type Meaning
0x11
Membership Query (if Group Address is 0.0.0.0)
0x1 Specific Group Membership Query (if Group Address
1 is Present)
0x1 Membership Report (version 2)
6
0x1 Leave a Group (version 2)
7
0x1 Membership Report (version 1)
Switch Management and Operating Concepts
Figure 5-15. IGMP Message Format
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