Configuring Mld Query And Response Parameters - HP A8800 Configuration Manual

Step
3. Configure the interface to
discard any MLD message
without the Router-Alert
option.
4. Enable the insertion of the
Router-Alert option into MLD
messages.

Configuring MLD query and response parameters

On startup, the MLDv1/v2 querier sends "startup query count" MLD general queries at the "startup
query interval", which is 1/4 of the "MLD query interval."
The MLDv1/v2 querier periodically sends MLD general queries at the "MLD query interval" to determine
whether any IPv6 multicast group member exists on the network. You can modify the query interval
based on the actual condition of the network.
The MLDv1 querier sends MLD multicast-address-specific queries at the MLD last listener query interval
when it
multicast-address-and-source-specific queries at the MLD last listener query interval when it receives a
done message or a report that changes multicast group and source mapping. The number of queries, or
the last listener query count equals the value of the robustness variable—the maximum number of packet
retransmissions.
After receiving
multicast-address-and-source-specific query) message, a host starts a timer for each IPv6 multicast group
it has joined. The timer is initialized to a random value in the range of 0 to the maximum response delay
(the host obtains the maximum response delay from the Maximum Response Delay field in the MLD query
message it received). When the timer value drops to 0, the host sends an MLD membership report
message to the corresponding IPv6 multicast group.
Proper setting of the maximum response delay of MLD query messages not only allows hosts to respond
to MLD query messages quickly, but also avoids bursts of MLD traffic on the network. Such bursts can
occur when a large number of hosts send reports at the same time when the corresponding timers expire
simultaneously.
For MLD general queries, you can configure the maximum response delay to fill their Maximum
•
Response Delay field.
For MLD multicast-address-specific query and multicast-address-and-source-specific query
•
messages, you can configure the last listener query interval to fill their Maximum Response Delay
field. That is, the maximum response time of MLD general query messages equals the last listener
query interval.
When multiple multicast routers exist on the same subnet, the MLD querier is responsible for sending MLD
query messages. If a non-querier router receives no MLD query from the querier within the other querier
present interval, it will assume that the querier has failed and a new querier election process begins.
Otherwise, the non-querier restarts the other querier present timer.
Make sure that the other querier present interval is greater than the MLD query interval. Otherwise the
MLD querier might frequently change.
Make sure that the MLD query interval is greater than the maximum response delay for MLD general
queries. Otherwise, multicast group members might be wrongly removed.
Command
mld require-router-alert
mld send-router-alert
receives an MLD
an MLD query
done message. The
(general query,
358
Remarks
By default, the device does not
check MLD messages for the
Router-Alert option.
By default, MLD messages carry
the Router-Alert option.
MLDv2 querier
multicast-address-specific
sends MLD
query, or