Configuring IGMP query and response parameters
The following are IGMP query and response parameters:
IGMP querier's robustness variable—Number of times for retransmitting IGMP queries in case of packet loss. A higher robustness variable makes the IGMP querier more robust, but increases the timeout time for multicast groups.
IGMP startup query interval—Interval at which an IGMP querier sends IGMP general queries at startup.
IGMP startup query count—Number of IGMP general queries that an IGMP querier sends at startup.
IGMP general query interval—Interval at which an IGMP querier sends IGMP general queries to check for multicast group members on the network.
IGMP last member query interval—In IGMPv2, it sets the interval at which a querier sends group-specific queries after receiving a leave message. In IGMPv3, it sets the interval at which a querier sends group-and-source-specific queries after receiving a report that changes multicast source and group mappings.
IGMP last member query count—In IGMPv2, it sets the number of group-specific queries that a querier sends after receiving a leave message. In IGMPv3, it sets the number of group-and-source-specific queries that a querier sends after receiving a report that changes multicast source and group mappings.
IGMP maximum response time—Maximum time before a receiver responds with a report to an IGMP general query. This per-group timer is initialized to a random value in the range of 0 to the maximum response time specified in the IGMP query. When the timer value for a group decreases to 0, the receiver sends an IGMP report to the group.
IGMP other querier present timer—Lifetime for an IGMP querier after a non-querier receives an IGMP general query. If the non-querier does not receive a new query when this timer expires, the non-querier considers that the querier has failed and starts a new querier election.
Configuration restrictions and guidelines
When you configure the IGMP query and response parameters, follow these restrictions and guidelines:
You can configure the IGMP query and response parameters globally for all interfaces in IGMP view or for an interface in interface view. For an interface, the interface-specific configuration takes priority over the global configuration.
To avoid frequent IGMP querier changes, set the IGMP other querier present timer greater than the IGMP general query interval. In addition, configure the same IGMP other querier present timer for all IGMP routers on the same subnet.
To avoid mistakenly deleting multicast receivers, set the IGMP general query interval greater than the maximum response time for IGMP general queries.
To speed up the response to IGMP queries and avoid simultaneous timer expirations that cause IGMP report traffic bursts, set an appropriate maximum response time.
For IGMP general queries, the maximum response time is set by the max-response-time command.
For IGMP group-specific queries and IGMP group-and-source-specific queries, the maximum response time equals the IGMP last member query interval.
The following configurations take effect only on the devices that run IGMPv2 and IGMPv3:
Maximum response time for IGMP general queries.
IGMP last member query interval.
IGMP last member query count.
IGMP other querier present interval.
Configuring the IGMP query and response parameters globally
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter IGMP view. | igmp [ vpn-instance vpn-instance-name ] | N/A |
3. Set the IGMP querier's robustness variable. | robust-count count | By default, the IGMP querier's robustness variable is 2. |
4. Set the IGMP startup query interval. | startup-query-interval interval | By default, the IGMP startup query interval equals one quarter of the IGMP general query interval. |
5. Set the IGMP startup query count. | startup-query-count count | By default, the IGMP startup query count equals the IGMP querier's robustness variable. |
6. Set the IGMP general query interval. | query-interval interval | By default, the IGMP general query interval is 125 seconds. |
7. Set the IGMP last member query interval. | last-member-query-interval interval | By default, the IGMP last member query interval is 1 second. |
8. Set the IGMP last member query count. | last-member-query-count count | By default, the IGMP last member query count equals the IGMP querier's robustness variable. |
9. Set the maximum response time for IGMP general queries. | max-response-time time | By default, the maximum response time for IGMP general queries is 10 seconds. |
10. Set the IGMP other querier present timer. | other-querier-present-interval interval | By default, the IGMP other querier present timer is calculated by using the following formula:[ IGMP general query interval ] × [ IGMP robustness variable ] + [ maximum response time for IGMP general queries ] / 2. |
Configuring the IGMP query and response parameters on an interface
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view. | interface interface-type interface-number | N/A |
3. Set the IGMP querier's robustness variable. | igmp robust-count count | By default, the IGMP querier's robustness variable is 2. |
4. Set the IGMP startup query interval. | igmp startup-query-interval interval | By default, the IGMP startup query interval equals one quarter of the IGMP general query interval. |
5. Set the IGMP startup query count. | igmp startup-query-count count | By default, the IGMP startup query count equals the IGMP querier's robustness variable. |
6. Set the IGMP general query interval. | igmp query-interval interval | By default, the IGMP general query interval is 125 seconds. |
7. Set the IGMP last member query interval. | igmp last-member-query-interval interval | By default, the IGMP last member query interval is 1 second. |
8. Set the IGMP last member query count. | igmp last-member-query-count count | By default, the IGMP last member query count equals the IGMP querier's robustness variable. |
9. Set the maximum response time for IGMP general queries. | igmp max-response-time time | By default, the maximum response time for IGMP general queries is 10 seconds. |
10. Set the IGMP other querier present timer. | igmp other-querier-present-interval interval | By default, the IGMP other querier present timer is calculated by using the following formula:[ IGMP general query interval ] × [ IGMP robustness variable ] + [ maximum response time for IGMP general queries ] / 2. |