Configuring MLD query and response parameters
About MLD query and response parameters
The following are MLD query and response parameters:
MLD querier's robustness variable—Number of times for retransmitting MLD queries in case of packet loss. A higher robustness variable makes the MLD querier more robust, but increases the timeout time for IPv6 multicast groups.
MLD startup query interval—Interval at which an MLD querier sends MLD general queries at startup.
MLD startup query count—Number of MLD general queries that an MLD querier sends at startup.
MLD general query interval—Interval at which an MLD querier sends MLD general queries to check for IPv6 multicast group members on the network.
MLD last listener query interval—In MLDv1, it sets the interval at which a querier sends multicast-address-specific queries after receiving a done message. In MLDv2, it sets the interval at which a querier sends multicast-address-and-source-specific queries after receiving a report that changes IPv6 multicast source and group mappings.
MLD last listener query count—In MLDv1, it sets the number of multicast-address-specific queries that the querier sends after receiving a done message. In MLDv2, it sets the number of multicast-address-and-source-specific queries that the querier sends after receiving a report that changes IPv6 multicast group and source mappings.
MLD maximum response time—Maximum time before a receiver responds with a report to an MLD 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 MLD query. When the timer value decreases to 0, the receiver sends an MLD report to the group.
MLD other querier present timer—Lifetime for an MLD querier after a non-querier receives an MLD 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.
Restrictions and guidelines
To avoid frequent MLD querier changes, set the MLD other querier present timer greater than the MLD general query interval. In addition, configure the same MLD other querier present timer for all MLD devices on the same subnet.
To speed up the response to MLD queries and avoid simultaneous timer expirations that cause MLD report traffic bursts, you must set an appropriate maximum response time.
For MLD general queries, the maximum response time is set by the max-response-time command.
For MLD multicast-address-specific queries or MLD multicast-address-and-source-specific queries, the maximum response time equals the MLD last listener query interval.
You can configure MLD query and response parameters globally for all interfaces in MLD view or for an interface in interface view. The interface-specific configuration takes priority over the global configuration.
Configuring the MLD query and response parameters globally
Enter system view.
system-view
Enter MLD view.
mld [ vpn-instance vpn-instance-name ]
Set the MLD querier's robustness variable.
robust-count count
By default, the MLD querier's robustness variable is 2.
Set the MLD startup query interval.
startup-query-interval interval
By default, the MLD startup query interval is equal to one quarter of the MLD general query interval.
Set the MLD startup query count.
startup-query-count count
By default, the MLD startup query count is equal to the MLD querier's robustness variable.
Set the MLD general query interval.
query-interval interval
By default, the MLD general query interval is 125 seconds.
Set the MLD last listener query interval.
last-listener-query-interval interval
By default, the MLD last listener query interval is 1 second.
Set the MLD last listener query count.
last-listener-query-count count
By default, the MLD last listener query count is equal to the MLD querier's robustness variable.
Set the maximum response time for MLD general queries.
max-response-time time
By default, the maximum response time for MLD general queries is 10 seconds.
Set the MLD other querier present timer.
other-querier-present-timeout time
By default, the MLD other querier present timer is calculated by using the following formula:[ MLD general query interval ] × [ MLD robustness variable ] + [ maximum response time for MLD general queries ] / 2.
Configuring the MLD query and response parameters on an interface
Enter system view.
system-view
Enter interface view.
interface interface-type interface-number
Set the MLD querier's robustness variable.
mld robust-count count
By default, the MLD querier's robustness variable is 2.
Set the MLD startup query interval.
mld startup-query-interval interval
By default, the MLD startup query interval is equal to one quarter of the MLD general query interval.
Set the MLD startup query count.
mld startup-query-count count
By default, the MLD startup query count is equal to the MLD querier's robustness variable.
Set the MLD general query interval.
mld query-interval interval
By default, the MLD general query interval is 125 seconds.
Set the MLD last listener query interval.
mld last-listener-query-interval interval
By default, the MLD last listener query interval is 1 second.
Set the MLD last listener query count.
mld last-listener-query-count count
By default, the MLD last listener query count is equal to the MLD querier's robustness variable.
Set the maximum response time for MLD general queries.
mld max-response-time time
By default, the maximum response time for MLD general queries is 10 seconds.
Set the MLD other querier present timer.
mld other-querier-present-timeout time
By default, the MLD other querier present timer is calculated by using the following formula:[ MLD general query interval ] × [ MLD robustness variable ] + [ maximum response time for MLD general queries ] / 2.