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.
![[NOTE: ]](images/note.png) | NOTE: 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. | |
Figure 22: Network diagram for MLD snooping proxying
As shown in Figure 22, Switch A works as an MLD snooping proxy. As a host from the perspective of the querier Router A, Switch A represents its attached hosts to send their membership reports and done messages to Router A.
Table 9: MLD message processing on an MLD snooping proxy
MLD message | Actions |
|---|---|
General query | When receiving an MLD general query, the proxy forwards it to all ports but the receiving port. In addition, the proxy generates a report according to the group memberships it maintains and sends the report out all router ports. |
Multicast-address-specific query | In response to the MLD group-specific query for a certain IPv6 multicast group, the proxy sends the report to the group out all router ports if the forwarding entry for the group still contains a member port. |
Report | When receiving a report for an IPv6 multicast group, the proxy looks up the multicast forwarding table for the entry for the multicast group. If the forwarding entry is found with the receiving port contained as a dynamic port in the outgoing port list, the proxy resets the aging timer for the entry. If the forwarding entry is found but the outgoing port list does not include the receiving port, the proxy adds the port to the outgoing port list as a dynamic member port and starts an aging timer for it. If no forwarding entry is found, the proxy creates the entry, adds the receiving port to the outgoing port list as a dynamic member port and starts an aging timer for the port, and then, sends a report to the group out all router ports. |
Done | In response to a done message for an IPv6 multicast group, the proxy sends a multicast-address-specific query for the group out the receiving port. After making sure that no member port is contained in the forwarding entry for the IPv6 multicast group, the proxy sends a done message for the group out all router ports. |