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Figure 41. Membership Reports: Joining and Filtering
Leaving and Staying in Groups
The following illustration shows how multicast routers track and refresh state changes in response to
group-and-specific and general queries.
1. Host 1 sends a message indicating it is leaving group 224.1.1.1 and that the included filter for 10.11.1.1
and 10.11.1.2 are no longer necessary.
2. The querier, before making any state changes, sends a group-and-source query to see if any other
host is interested in these two sources; queries for state-changes are retransmitted multiple times. If
any are, they respond with their current state information and the querier refreshes the relevant state
information.
3. Separately in the following illustration, the querier sends a general query to 224.0.0.1.
4. Host 2 responds to the periodic general query so the querier refreshes the state information for that
group.
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Internet Group Management Protocol (IGMP)