1-4How MLD Snooping WorksA switch running MLD snooping performs different actions when it receives different MLD messages, asfollows:The description about adding or deleting a port in this section is only for a dynamic port. Static ports canbe added or deleted only through the corresponding configurations. For details, see Configuring StaticPorts.General queriesThe MLD querier periodically sends MLD general queries to all hosts and routers (FF02::1) on the localsubnet to find out whether IPv6 multicast group members exist on the subnet.Upon receiving an MLD general query, the switch forwards it through all ports in the VLAN except theport on which it received the MLD query and performs the following:z If the port on which it the switch received the MLD query is a dynamic router port in its router portlist, the switch resets the aging timer for this dynamic router port.z If the port is not included in its router port list, the switch adds it into its router port list as a dynamicrouter port and sets an aging timer for it.Membership reportsA host sends an MLD report to the MLD querier in the following circumstances:z Upon receiving an MLD query, an IPv6 multicast group member host responds with an MLD report.z When intended to join an IPv6 multicast group, a host sends an MLD report to the MLD querier toannounce that it is interested in the multicast information addressed to that IPv6 multicast group.Upon receiving an MLD report, the switch forwards it through all the router ports in the VLAN, resolvesthe address of the reported IPv6 multicast group, and performs the following to the receiving port:z If no forwarding table entry exists for the reported IPv6 multicast group, the switch creates an entry,adds the port as a dynamic member port to the outgoing port list, and starts a member port agingtimer for that port.z If a forwarding table entry exists for the reported IPv6 multicast group, but the port is not included inthe outgoing port list for that group, the switch adds the port as a dynamic member port to theoutgoing port list, and starts a member port aging timer for that port.z If a forwarding table entry exists for the reported IPv6 multicast group and the port is included in theoutgoing port list, which means that this port is already a dynamic member port, the switch resetsthe member port aging timer for that port.
