H3C Technologies H3C S7500E Series Switches - Manual (Page 262)

9-6
z If the forwarding table entry exists and the outgoing port list contains the port, the switch
forwards the MLD done message to all router ports in the native VLAN. Because the switch
does not know whether any other hosts attached to the port are still listening to that IPv6
multicast group address, the switch 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.
Upon 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. Upon receiving
the MLD multicast-address-specific query, the switch forwards it through all the router ports in
the VLAN and all member ports for that IPv6 multicast group, and performs the following to the
receiving port:
z If any MLD report in response to the MLD multicast-address-specific query is received on
the port (suppose it is a dynamic member port) before its aging timer expires, this means
that some host attached to the port is receiving or expecting to receive IPv6 multicast data
for that IPv6 multicast group. The switch resets the aging timer for the port.
z If no MLD report in response to the MLD multicast-address-specific query is received on
the port before its aging timer expires, this means that no hosts attached to the port are still
listening to that IPv6 multicast group address. The switch removes the port from the
outgoing port list of the forwarding table entry for that IPv6 multicast group when the aging
timer expires.
MLD Snooping Proxying
You can configure the MLD snooping proxying function on an edge device to reduce the number
of MLD reports and done messages sent to its upstream device. The device configured with
MLD snooping proxying is called an MLD snooping proxy. It is a host from the perspective of its
upstream device.
Even though an MLD Snooping proxy is a host from the perspective of its upstream device, the
MLD membership report suppression mechanism for hosts does not take effect on it. For the
MLD report suppression mechanism for hosts, refer to MLD Configuration in the IP Multicast
Configuration Guide.