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Configuration prerequisites
Before you configure an MLD snooping querier, complete the following tasks:
•
Enable MLD snooping in the VLAN.
•
Determine the interval for sending MLD general queries.
•
Determine the MLD last-listener query interval.
•
Determine the maximum response delay 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 run MLD, a multicast router or Layer 3 multicast switch regularly
sends MLD general queries. This allows all Layer 3 multicast devices to establish and maintain
multicast forwarding entries for correctly forwarding multicast traffic at the network layer. This router
or Layer 3 switch is called the "MLD querier."
However, a Layer 2 multicast device does not support MLD, and therefore cannot send queries by
default. To ensure IPv6 multicast data forwarding at the data link layer on a network without Layer 3
multicast devices, you can configure the Layer 2 device as an MLD snooping querier. In this way, the
Layer 2 device sends MLD queries, and establishes and maintains multicast forwarding entries.
Configuration guidelines
Do not configure an MLD snooping querier in an IPv6 multicast network that runs MLD. An MLD
snooping querier does not participate in MLD querier elections. However, 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 "
."
Configuration procedure
To enable the MLD snooping querier in a VLAN:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter VLAN view.
vlan
vlan-id
N/A
3.
Enable the MLD snooping
querier.
mld-snooping querier
Disabled by default.
Configuring parameters for MLD queries and responses
CAUTION:
Make sure that the interval for sending MLD general queries is greater than the maximum response
delay for MLD general queries. Otherwise, IPv6 multicast members might be removed by mistake.
You can modify the MLD general query interval based on the actual condition of the network.
A multicast listening host starts a timer for each IPv6 multicast group that it has joined when it
receives an MLD query (general query or multicast-address-specific query). This timer is initialized to
a random value ranging from 0 to the maximum response delay advertised in the MLD query
message. When the timer value decreases to 0, the host sends an MLD report to the IPv6 multicast
group.
