95
•
For IGMP group-specific queries and IGMP group-and-source-specific queries, the maximum
response time equals 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 when the other querier
present timer expires, it considers that the querier has failed and starts a new querier election. Otherwise,
the non-querier router resets the other querier present timer.
Configuration guidelines
•
Make sure that the other querier present interval is greater than the IGMP general query interval.
Otherwise the IGMP querier might change frequently on the network.
•
Make sure that the IGMP general query interval is greater than the maximum response time for
IGMP general queries. Otherwise, multicast group members might be wrongly removed.
•
The configurations of the maximum response time for IGMP general queries, the IGMP last member
query interval and the IGMP other querier present interval are effective only for IGMPv2 and
IGMPv3.
Configuration procedure
To configure IGMP query and response parameters globally:
Step
Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter public network IGMP
view or VPN instance IGMP
view.
igmp
[
vpn-instance
vpn-instance-name
]
N/A
3.
Configure the IGMP querier's
robustness variable.
robust-count
robust-value
2 by default.
4.
Configure the startup query
interval.
startup-query-interval
interval
By default, the startup query
interval is 1/4 of the "IGMP
general query interval".
5.
Configure the startup query
count.
startup-query-count
value
By default, the startup query count
is set to the IGMP querier's
robustness variable.
6.
Configure the IGMP general
query interval.
timer query
interval
60 seconds by default.
7.
Configure the maximum
response time for IGMP
general queries.
max-response-time
interval
10 seconds by default.
8.
Configure the IGMP
last-member query interval.
last-member-query-interval
interval
1 second by default.
9.
Configure the other querier
present interval.
timer other-querier-present
interval
By default, the other querier
present interval is [ IGMP general
query interval ] × [ IGMP
robustness variable ] + [ maximum
response time for IGMP general
queries ] / 2.
To configure IGMP query and response parameters on an interface: