H3C Technologies H3C S10500 Series Switches - Manual (Page 284)

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Configuring MLD snooping querier
Configuration prerequisites
Before you configure MLD snooping querier, complete the following tasks:
• Enable MLD snooping in the VLAN
• Determine the MLD general query interval
• Determine the MLD last-member query interval
• Determine the maximum response time for MLD general queries
• Determine the source IPv6 address of MLD general queries
• Determine the source IPv6 address of MLD multicast-address-specific queries
Enabling MLD snooping querier
In an IPv6 multicast network that runs MLD, a multicast router or Layer 3 multicast switch sends MLD
queries, so that all Layer 3 multicast devices can establish and maintain multicast forwarding entries, in
order to forward multicast traffic correctly at the network layer. This router or Layer 3 switch is called the
“MLD querier.”
However, a Layer 2 multicast switch does not support MLD. Therefore, it cannot send MLD general
queries by default. When you enable MLD snooping querier on a Layer 2 switch in a VLAN where
multicast traffic is switched only at Layer 2 and no Layer 3 multicast devices are present, the Layer 2
switch sends MLD queries, so that multicast forwarding entries can be created and maintained at the
data link layer.
Follow these steps to enable the MLD snooping querier:
To do... Use the command... Remarks
Enter system view system-view —
Enter VLAN view vlan vlan-id —
Enable the MLD snooping querier mld-snooping querier
Required
Disabled by default.
CAUTION:
It is meaningless to configure an MLD snooping querier in an IPv6 multicast network that runs MLD.
Although an MLD snooping querier does not participate in MLD querier elections, it might affect MLD
querier elections because it sends MLD general queries with a low source IPv6 address. For more
information about MLD querier, see the chapter “MLD configuration.”
Configuring MLD queries and responses
You can set the MLD general query interval based on the actual conditions of the network.
After receiving an MLD query (general query or multicast-address-specific query), a host starts a timer for
each IPv6 multicast group that it has joined. This timer is initialized to a random value in the range of 0
to the maximum response time (the host obtains the value of the maximum response time from the Max
Response Time field in the MLD query that it received). When the timer value comes down to 0, the host
sends an MLD report to the corresponding IPv6 multicast group.