For setup, refer to Figure IGMP- Topology 1.
The IGMP last member query interval is the time between Group-Specific query messages, including those sent in response to Leave-Group messages.
When the router that is acting as the querier receives a Leave-Group message from a host, the routing device sends multiple Group-Specific Queries at a specific interval to the group still there. The interval at which the Group-Specific Queries are sent is called last member query interval.
To avoid IGMP report traffic bursts, the amount of time it takes a routing device to detect the loss of the last member of a group is configurable with the commands shown below.By default, the global IGMP last member query interval for this device is 10 seconds. in the example below, a larger last member query interval of 20 seconds is configured to decrease traffic bursts. Traffic bursts refer to nonuniform pattern of packets transmission- periods with high and low data transmission rate.