H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – Multicast
H3C S7500E Series Ethernet Switches Chapter 2 IGMP Snooping Configuration
2-15
Caution:
It is meaningless to configure an IGMP Snooping querier in a multicast network running
IGMP. Although an IGMP Snooping querier does not take part in IGMP querier
elections, it may affect IGMP querier elections because it sends IGMP general queries
with a low source IP address.
2.5.3 Configuring IGMP Queries and Responses
You can tune the IGMP general query interval based on actual condition of the network.
Upon receiving an IGMP query (general query or group-specific query), a host starts a
timer for each multicast group it has joined. This timer is initialized to a random value in
the range of 0 to the maximum response time (the host obtains the value of the
maximum response time from the Max Response Time field in the IGMP query it
received). 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
expire 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, you can configure the IGMP last-member query
interval to fill their Max Response time field. Namely, for IGMP group-specific
queries, the maximum response time equals to the IGMP last-member query
interval.
I. Configuring IGMP queries and responses globally
Follow these steps to configure IGMP queries and responses globally:
To do... Use the command... Remarks
Enter system view
system-view
—
Enter IGMP Snooping view
igmp-snooping
—
Configure the maximum
response time to IGMP
general queries
max-response-time
interval
Optional
10 seconds by default
Configure the IGMP
last-member query interval
last-member-query-i
nterval interval
Optional
1 second by default