3Com Switch 8800 Family Configuration Guide

448 CHAPTER 42: IGMP CONFIGURATION
By default, the value is twice the IGMP query message interval, namely 120
seconds.
Configuring Maximum
Response Time for IGMP
Query Message
When a router receives a query message, the host will set a timer for each
multicast group it belongs to. The value of the timer is randomly selected between
0 and the maximum response time. When any timer becomes 0, the host will send
the membership report message of the multicast group.
Setting the maximum response time reasonably can enable the host to respond to
query messages quickly. In this case, the router can fast master the existing status
of the members of the multicast group.
Perform the following configuration in interface view.
The smaller the maximum query response time value, the faster the router prunes
groups. The actual response time is a random value in the range from 1 to 25
seconds. By default, the maximum query response time is 10 seconds.
Configuring the limit of
IGMP groups on an
interface
If there is no limit to the number of IGMP groups added on a router interface or a
router, the router memory may be exhausted, which may cause router failure.
You can set number limit for the IGMP groups added on the interface, but not the
number limit for the IGMP groups added in the router, which is defined by the
system.
Perform the following configuration in VLAN interface view.
By default, the maximum number of IGMP groups on an interface is 512.
Tabl e 439 Configure the present time of IGMP querier
Operation Command
Change the present time of IGMP querier igmp timer other-querier-present seconds
Restore the default value undo igmp timer other-querier-present
Tabl e 440 Configure the maximum response time for IGMP query message
Operation Command
Configure the maximum response time for
IGMP query message
igmp max-response-time seconds
Restore the maximum query response time to
the default value
undo igmp max-response-time
Tabl e 441 Configure the limit of IGMP groups on an interface
Operation Command
Configure the limit of IGMP groups on an
interface
igmp group-limit limit
Restore the limit of IGMP groups on an
interface to the default value
undo igmp group-limit