H3C Technologies H3C S7500E Series Switches - Manual (Page 261)

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z If the port is not included in its router port list, the switch adds it into its router port list as a
dynamic router port and sets an aging timer for it.
Membership reports
A 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 to announce 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,
resolves the 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 aging timer for that port.
z If a forwarding table entry exists for the reported IPv6 multicast group, but the port is not
included in the outgoing port list for that group, the switch adds the port as a dynamic
member port to the outgoing 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 the outgoing port list, which means that this port is already a dynamic member
port, the switch resets the member port aging timer for that port.
A switch does not forward an MLD report through a non-router port. This is because if the
switch forwards a report message through a member port, all the attached hosts listening to the
reported IPv6 multicast address will suppress their own reports upon receiving this report
according to the MLD report suppression mechanism for hosts, and this will prevent the switch
from knowing whether the reported multicast group still has active members attached to that
port.
For the MLD report suppression mechanism of hosts, refer to MLD Configuration in the IP
Multicast Configuration Guide.
Done messages
When a host leaves an IPv6 multicast group, the host sends an MLD done message to the
multicast router.
When the switch receives an MLD done message on a dynamic member port, the switch first
checks whether a forwarding table entry for the IPv6 multicast group address in the message
exists, and, if one exists, whether the outgoing port list contains the port.
z If the forwarding table entry does not exist or if the outgoing port list does not contain the
port, the switch discards the MLD done message instead of forwarding it to any port.