MLD proxying
As shown in Figure 102, in a simple tree-shaped topology, it is not necessary to configure IPv6 multicast routing protocols, such as IPv6 PIM, on edge devices. Instead, you can configure MLD proxying on these devices. With MLD proxying configured, the edge device acts as an MLD proxy:
For the upstream MLD querier, the MLD proxy device acts as a host.
For the downstream receiver hosts, the MLD proxy device acts as an MLD querier.
Figure 102: Network diagram
The following interfaces are defined in MLD proxying:
Host interface—An interface that is in the direction toward the root of the multicast forwarding tree. A host interface acts as a receiver host that is running MLD. MLD proxying must be enabled on this interface. This interface is also called the "proxy interface."
Router interface—An interface that is in the direction toward the leaf of the multicast forwarding tree. A router interface acts as a router that is running MLD. MLD must be configured on this interface.
An MLD proxy device maintains a group membership database, which stores the group memberships on all the router interfaces. The host interfaces and router interfaces perform actions based on this membership database.
The host interfaces respond to queries according to the membership database or sends join/done messages when the database changes.
The router interfaces participate in the querier election, send queries, and maintain memberships based on received MLD reports.