3Com 8807 Configuration Manual page 447

Configuring the Present
Time of IGMP Querier
When other hosts receive the message from the IGMP querier and are
■
interested in this group, they return the IGMP Membership Report message
within the defined maximum response time.
If IGMP querier receives the report messages from other hosts within the period
■
equal to robust-value × seconds, it continues membership maintenance for this
group.
If it receives no report message from any other host within this period, it
■
reckons this as timeout and ends membership maintenance for this group.
This configuration takes effect only when the querier runs IGMP version 2. If a
host runs IGMP Version 1, it does not send IGMP Leave Group message when it
leaves a group. In this case, this configuration does not work for the host.
Please perform the following configurations in VLAN interface view.
Configuring interval for querying IGMP packets
Table 437 Configure interval for querying IGMP packets
Operation
Configure interval for querying IGMP packets
Restore the default query interval
By default, the interval is 1 second.
Configuring the number of last member querying
Table 438 Configure the number of last member querying
Operation
Configure number of last member querying
Restore the default number of querying
By default, an IGMP group-specific query message is sent for twice.
On shared network, namely a network segment where multiple multicast routers
exist, a query router (querier for short) sends query messages on the interface
regularly. If a non-query router fails to receive messages from the querier within a
period of time, it will deem that the querier has failed and take over the job of the
original querier.
In the IGMP V1 version, the querier selection is determined by the multicast
routing protocol; in the IGMP V2 version, the router with the smallest IP address
on a shared network segment acts as the querier.
The IGMP querier presence time is the period of time before the router takes over
as the querier sending query messages, after the previous querier has stopped
doing so.
Perform the following configuration in VLAN interface view.
IGMP Configuration
Command
igmp lastmember-queryinterval seconds
undo igmp lastmember-queryinterval
Command
igmp robust-count robust-value
undo igmp robust-count
447