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General Query Interval: The interval between the multicast router sends out general queries.

Last Listener Query Interval: The interval between the switch sends out MASQs.

Last Listener Query Count: The number of MASQs that the switch sends before aging out a

multicast address when there is no MLD report response.

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MLD Snooping Process

1. General Query

The MLD router regularly sends MLD general queries to query if the multicast groups contain

any members. When receiving MLD general queries, the switch will forward them to all other

ports in the VLAN. The receiving port will be processed: if the receiving port is not a router port

yet, it will be added to the router port list with its router port aging time specified; if the

receiving port is already a router port, its router port aging time will be directly reset.

2. Membership Report

The host will send MLD report messages when it applies for joining a multicast group or

responds to the MLD query message from the router.

When receiving MLD report message, the switch will forward the report message via the router

port in the VLAN, and analyze the message to get the address of the multicast group the host

applies for joining. If the multicast group does not exist, it will create the group entry. The

receiving port will be processed: if the receiving port is a new member port, it will be added to

the forward list of the multicast group with its member port aging time specified; if the receiving

port is already a member port, its member port aging time will be directly reset.

3. Member Leave

The host will send MLD Done message when leaving a multicast group to inform the router of

its leaving.

When Immediate Leave is not enabled in a VLAN and a Done message is received on a port of

this VLAN, the switch will generate MASQs on this port to check if there are other members in

this multicast group. The user can control when a port membership is removed for an exiting

address in terms of the number and interval of MASQs. If there is no Report message received

from this port during the switch maximum response time, the port on which the MASQ was sent

is deleted from the multicast group. If the deleted port is the last member of the multicast

group, the multicast group is also deleted. The switch will send Done message to the router

ports of the VLAN.

In IPv6，Layer 2 switches can use Multicast Listener Discovery (MLD) Snooping to limit the

flooding of multicast traffic by dynamically configuring Layer 2 interfaces so that IPv6 multicast

data is selectively forwarded to a list of ports that want to receive the data. This list is

constructed by snooping IPv6 multicast control packets.

The MLD Snooping function can be implemented on Snooping Config, Port Config, VLAN

Config, Multicast VLAN, Querier Config, Profile Config, Profile Binding and Packet Statistics

pages.

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