D-Link DES-3326 User Manual page 123

The IGMP Type codes are shown below:
Type Meaning
Membership Query (if Group Address is 0.0.0.0)
0X11
0x11 Specific Group Membership Query (if Group Address is
Present)
0x16 Membership Report (version 2)
0x17 Leave a Group (version 2)
0x12 Membership Report (version 1)
Each host can join a mulitcast group or leave a mulitcast group
that it previously joined. IGMP packets are used by routers to
keep track of group member ships in their immediately
connected subnetworks. The following rules apply:
A host sends an IGMP "report" to join a group
A host will never send a report when it wants to leave a
group (for version 1).
A host will send a "leave" report when it wants to leave a
group (for version 2).
Multicast routers send IGMP queries (to the all-hosts
group address: 224.0.0.1) periodically to see whether any
group members exist on their subnetworks. If there is no
Switch Management and Operating Concepts
24-port NWay Ethernet Switch User's Guide
Figure 5-17. IGMP Message Format
Table 5-11. IGMP Type Codes
107