Users Guide

timer expires; in version 2, if another host responds before the timer expires, the timer is nullified, and no
response is sent.
The maximum response time is the amount of time that the querier waits for a response to a query before
taking further action. The querier advertises this value in the query (refer to the illustration in IGMP Version 2).
Lowering this value decreases leave latency but increases response burstiness because all host membership
reports must be sent before the maximum response time expires. Inversely, increasing this value decreases
burstiness at the expense of leave latency.
When the querier receives a leave message from a host, it sends a group-specific query to the subnet. If no
response is received, it sends another. The amount of time that the querier waits to receive a response to the
initial query before sending a second one is the last member query interval (LMQI). The switch waits one
LMQI after the second query before removing the group from the state table.
• Adjust the period between queries.
INTERFACE mode
ip igmp query-interval
• Adjust the maximum response time.
INTERFACE mode
ip igmp query-max-resp-time
• Adjust the last member query interval.
INTERFACE mode
ip igmp last-member-query-interval
Enabling IGMP Immediate-Leave
If the querier does not receive a response to a group-specific or group-and-source query, it sends another
(querier robustness value). Then, after no response, it removes the group from the outgoing interface for the
subnet.
IGMP immediate leave reduces leave latency by enabling a router to immediately delete the group
membership on an interface after receiving a Leave message (it does not send any group-specific or group-
and-source queries before deleting the entry).
• Configure the system for IGMP immediate leave.
ip igmp immediate-leave
• View the enable status of the IGMP immediate leave feature.
EXEC Privilege mode
show ip igmp interface
View the enable status of this feature using the command from EXEC Privilege mode, as shown in the
example in Selecting an IGMP Version.
Internet Group Management Protocol (IGMP) 456