Interlogix GE-DSSG-244-POE User Manual - Manual (Page 133)

IFS NS3601-24P/4S GE-DSSG-244 and 244-POE User Manual
131
Figure 4-8-2 Multicast flooding
Figure 4-8-3 IGMP Snooping multicast stream control
IGMP Versions 1 and 2
Multicast groups allow members to join or leave at any time. IGMP provides the method for members and multicast routers to
communicate when joining or leaving a multicast group.
IGMP version 1 is defined in RFC 1112. It has a fixed packet size and no optional data.
The format of an IGMP packet is shown below:
IGMP Message Format
Octets
0 8 16 31
Type Response Time Checksum
Group Address (all zeros if this is a query)
The IGMP Type codes are shown below:
Type Meaning
0x11 Membership Query (if Group Address is 0.0.0.0)
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)
IGMP packets enable multicast routers to keep track of the membership of multicast groups, on their respective sub networks. The