R3303-HP HSR6800 Routers IP Multicast Configuration Guide

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multicast group and multicast source mapping change report. The number of queries, or the last listener
query count, equals the robustness variable—the maximum number of packet retransmissions.
A multicast listening host starts a timer for each IPv6 multicast group that it has joined when it receives an
MLD query (general query), multicast-address-specific query, or multicast-address-and-source-specific
query. The timer is initialized to a random value in the range of 0 to the maximum response delay
advertised in the MLD query message. When the timer decreases to 0, the host sends an MLD
membership report message to the IPv6 multicast group.
To speed up the response of hosts to MLD queries and avoid simultaneous timer expirations causing MLD
report traffic bursts, you must correctly set the maximum response delay:
• For MLD general queries, the maximum response delay is set by the max-response-time command.
• For MLD multicast-address-specific query and multicast-address-and-source-specific query
messages, the maximum response delay 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 when the other querier
present interval expires, it considers the querier as having failed and starts a new querier election.
Otherwise, the non-querier resets the other querier present timer.
When you configure MLD query and response parameters, following these guidelines:
• To avoid frequent MLD querier changes, set the other querier present interval greater than the MLD
query interval.
• To avoid incorrect multicast group member removals, set the MLD query interval greater than the
maximum response delay for MLD general queries.
Configuring MLD query and response parameters globally
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter MLD view.
mld N/A
3. Configure the MLD querier's
robustness variable.
robust-count robust-value
2 by default.
A higher robustness variable
makes the MLD querier more
robust but results in a longer IPv6
multicast group timeout time.
4. Configure the startup query
interval.
startup-query-interval interval
By default, the startup query
interval is one-quarter of the "MLD
query interval."
5. Configure the startup query
count.
startup-query-count value
By default, the startup query count
is the same as the MLD querier's
robustness variable.
6. Configure the MLD query
interval.
timer query interval 125 seconds by default.
7. Configure the maximum
response delay for MLD
general query messages.
max-response-time interval 10 seconds by default.
8. Configure the MLD last
listener query interval.
last-listener-query-interval interval
1 second by default.