D-Link DES-3326SR User Manual page 103

DES-3326SR Layer 3 Fast Ethernet Switch User's Guide
IGMP version 2 introduces a few extensions to IGMP version 1
such as, the election of a single multicast querier for each
network, explicit 'leave' reports, and queries that are specific to
a particular multicast group.
The router with the lowest IP address is elected as the querier.
The explicit group leave message is added to decrease latency,
and routers can ask for membership reports from a particular
multicast group ID.
The transition states a host will go through to join or leave a multicast
group are shown in the diagram below.
Figure 5-16. IGMP State Transitions
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