H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 51)

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After receiving an MLD general query, the Layer 2 device forwards it through all ports in the VLAN
(except the receiving port that received the MLD general query). The Layer 2 device also performs one of
the following actions:
• If the receiving port is a dynamic router port in the router port list, resets the aging timer for this
dynamic router port.
• If the receiving port is not in the router port list, adds it into its router port list, and sets an aging timer
for it.
When receiving a membership report
A host sends an MLD report to the MLD querier for the following purposes:
• If the host has been an IPv6 multicast group member, responds with an MLD report.
• Applies for joining an IPv6 multicast group.
After receiving an MLD report, the Layer 2 device forwards it through all the router ports in the VLAN,
resolves the address of the reported IPv6 multicast group, and performs one of the following actions:
• If no forwarding table entry exists for the reported IPv6 multicast group, creates a forwarding entry,
adds the receiving port as a dynamic member port to the outgoing port list, and starts a member
port aging timer for that port.
• If a forwarding table entry exists for the reported IPv6 multicast group, but the receiving port is not
included in the outgoing port list for that group, adds the port as a dynamic member port to the
outgoing port list, and starts an aging timer for that port.
• If a forwarding table entry exists for the reported IPv6 multicast group and the receiving port is
included in the outgoing port list, resets the member port aging timer for that port.
A Layer 2 device does not forward an MLD report through a non-router port. If the Layer 2 device
forwards a report message through a member port, the MLD report suppression mechanism causes all
the attached hosts that are monitoring the reported IPv6 multicast address suppress their own reports.
This makes the Layer 2 device unable to know whether the reported multicast group still has active
members attached to that port.
When receiving a done message
When a host leaves an IPv6 multicast group, the host sends an MLD done message to the multicast router.
When the Layer 2 device receives an MLD done message on a dynamic member port, the Layer 2 device
first examines 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.
• If the forwarding table entry does not exist or if the outgoing port list does not contain the port, the
Layer 2 device discards the MLD done message instead of forwarding it to any port.
• If the forwarding table entry exists and the outgoing port list contains the port, the Layer 2 device
forwards the MLD done message to all router ports in the native VLAN. Because the Layer 2 device
does not know whether any other hosts attached to the port are still listening to that IPv6 multicast
group address, the Layer 2 device does not immediately remove the port from the outgoing port list
of the forwarding table entry for that group. Instead, it resets the aging timer for the port.
After receiving an MLD done message from a host, the MLD querier resolves the IPv6 multicast group
address in the message and sends an MLD multicast-address-specific query to that IPv6 multicast group
address through the port that received the MLD done message. After receiving the MLD
multicast-address-specific query, the Layer 2 device forwards it through all the router ports in the VLAN
and all member ports for that IPv6 multicast group. The Layer 2 device also performs the following
judgment on the port that received the MLD done message: