3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring IGMP Performance Parameters 533
n
■ If not statically configured, the other querier present interval is [ IGMP general
query interval ] times [ IGMP robustness variable ] plus [ maximum response
time for IGMP general queries ] divided by two. By default, the values of these
three parameters are 60 (seconds), 2 and 10 (seconds) respectively, so the
default value of the other querier present interval = 60 × 2 + 10 / 2 = 125
(seconds).
■ If statically configured, the other querier present interval takes the configured
value.
c
CAUTION:
■ If the statically configured other querier present interval is shorter than the
IGMP general query interval, the querier election may be triggered frequently.
■ In configuration, make sure that the maximum response time for IGMP general
queries is less than the IGMP general query interval; otherwise, multicast group
members may be wrongly removed.
■ The configurations of the maximum response time for IGMP general queries,
IGMP last-member query interval and other querier present interval are
effective only when the IGMP querier runs IGMPv2 or IGMPv3.
Configuring IGMP Fast
Leave
To enable fast response to leave messages of hosts, you can enable the IGMP fast
leave feature.
With the fast leave function enabled, after an IGMP querier receives a leave
message from a host, it will not send IGMP group-specific queries to the group
being left; instead, it will send a leave notification to the upstream. As a result, the
leave latency is reduced on one hand, and the network bandwidth is saved on the
other.
Configuring IGMP fast leave globally
Follow these steps to enable IGMP fast leave globally:
n
Configured in IGMP view, the fast leave feature takes effect only on POS interfaces
rather than VLAN interfaces.
Configuring IGMP fast leave for an interface
Follow these steps to configure IGMP fast leave for an interface:
Configure the other querier
present interval
igmp timer
other-querier-present
interval
Optional
For the system default, see
"Note" below
To do... Use the command... Description
To do... Use the command... Description
Enter system view system-view -
Enter IGMP view igmp -
Enable IGMP fast leave fast-leave [ group-policy
acl-number ]
Required
Disabled by default