194
•
If a match is found and the receiving port is not the only outgoing interface in the forwarding
entry, the Layer 2 device performs the following actions:
Discards the MLD done message.
Sends an MLD multicast-address-specific query to identify whether the group has active
listeners attached to the receiving port.
Sets the aging timer for the receiving port to twice the MLD last listener query interval.
•
If a match is found and the receiving port is the only outgoing interface in the forwarding entry,
the Layer 2 device performs the following actions:
Forwards the MLD done message to all router ports in the VLAN or VSI.
Sends an MLD multicast-address-specific query to identify whether the group has active
listeners attached to the receiving port.
Sets the aging timer for the receiving port to twice the MLD last listener query interval.
After receiving the MLD done message on a port, the MLD querier resolves the IPv6 multicast group
address in the message. Then, it sends an MLD multicast-address-specific query to the IPv6
multicast group through the receiving port.
After receiving the MLD multicast-address-specific query, the Layer 2 device forwards the query
through all router ports and member ports of the group in the VLAN or VSI. Then, it waits for the
responding MLD report from the directly connected hosts. For the dynamic member port that
received the done message, the Layer 2 device also performs one of the following actions:
•
If the port receives an MLD report before the aging timer expires, the Layer 2 device resets the
aging timer for the port.
•
If the port does not receive any MLD report messages when the aging timer expires, the Layer
2 device removes the port from the forwarding entry for the IPv6 multicast group.
MLD snooping proxying
, to reduce the number of MLD report and done messages received by the
upstream device, you can enable MLD snooping proxying on the edge device. With MLD snooping
proxying enabled, the edge device acts as a host for the upstream MLD snooping querier to send
MLD report and done messages to Router A. The host MLD report suppression mechanism on the
edge device does not take effect.
Figure 67 MLD snooping proxying
The MLD snooping proxy device processes different MLD messages as follows:
•
General query.
Host A
Receiver
Host B
Host C
Receiver
MLD Querier
Router A
Proxy
Switch A
Query from Router A
Report from Switch A
Query from Switch A
Report from Host
IP network
