165
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)
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