Planet GSD-802S User Manual page 84

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 sub networks. If there is no response from a particular group, the router assumes that there are no
group members on the network.
The Time-to-Live (TTL) field of query messages is set to 1 so that the queries will not be forwarded to other sub networks.
IGMP version 2 introduces some enhancements such as a method to elect a multicast queried for each LAN, an explicit
leave message, and query messages that are specific to a given group.
The states a computer will go through to join or to leave a multicast group are shown below:
Leave Group
(Stop Timer)
Join Group
(Send Report,
Start Timer)
Delaying Member
IGMP State Transitions
User's Manual of GSD-800S / GSD-802S / GSD-802PS
Non-Member
Leave Group
Query Received
(Start Timer)
Report Received
(Stop Timer)
Timer Expried
(Send report)
Idle Member