H3C Technologies H3C S7500E Series Switches - Manual (Page 123)

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joined. This timer is initialized to a random value in the range of 0 to the maximum response
time, which is derived from the Max Response Time field in the IGMP query. When the timer
value comes down to 0, the host sends an IGMP report to the corresponding multicast group.
An appropriate setting of the maximum response time for IGMP queries allows hosts to respond
to queries quickly and avoids bursts of IGMP traffic on the network caused by reports
simultaneously sent by a large number of hosts when the corresponding timers expires
simultaneously.
z For IGMP general queries, you can configure the maximum response time to fill their Max
Response time field.
z For IGMP group-specific queries and IGMP group-and-source-specific queries, you can
configure the IGMP last-member query interval to fill their Max Response time field.
Namely, for IGMP group-specific queries and IGMP group-and-source-specific queries, the
maximum response time equals to the IGMP last-member query interval.
When multiple multicast routers exist on the same subnet, the IGMP querier is responsible for
sending IGMP queries. If a non-querier router receives no IGMP query from the querier within
the “other querier present interval”, it will assume the querier to have expired and a new querier
election process is launched; otherwise, the non-querier router will reset its “other querier
present timer”.
Configuring IGMP query and response parameters globally
Follow these steps to configure IGMP query and response parameters globally:
To do... Use the command... Remarks
Enter system view system-view —
Enter public instance IGMP view
or VPN instance IGMP view
igmp [ vpn-instance
vpn-instance-name ]
—
Configure the IGMP querier’s
robustness variable
robust-count robust-value
Optional
2 by default
Configure the startup query
interval
startup-query-interval interval
Optional
By default, the startup query
interval is 1/4 of the “IGMP
general query interval”.
Configure the startup query
count
startup-query-count value
Optional
By default, the startup query
count is set to the IGMP
querier’s robustness variable.
Configure the IGMP general
query interval
timer query interval
Optional
60 seconds by default
Configure the maximum
response time for IGMP general
queries
max-response-time interval
Optional
10 seconds by default