3com S7906E Installationsanweisungen
1-9
The MLD SSM mapping feature does not process MLDv2 reports.
For more information about the IPv6 SSM group range, refer to IPv6 PIM Configuration in the IP
Multicast Volume.
MLD Proxying
In some simple tree-shaped topologies, it is not necessary to configure complex IPv6 multicast routing
protocols, such as IPv6 PIM, on the boundary devices. Instead, you can configure MLD proxying on
these devices. With MLD proxying configured, the device serves as a proxy for the downstream hosts to
send MLD messages, maintain group memberships, and implement IPv6 multicast forwarding based
on the memberships. In this case, each MLD proxy device is a host but no longer an IPv6 PIM neighbor
to the upstream device.
Figure 1-6 Network diagram for MLD proxying
As shown in
, two types of interfaces are defined on a MLD proxy device:
z
Upstream interface: Also referred to as the proxy interface. A proxy interface is an interface on
which MLD proxying is configured. It is in the direction toward the root of the multicast forwarding
tree. An upstream interface acts as a host running MLD; therefore, it is also called host interface.
z
Downstream interface: An interface that is running MLD and not in the direction toward the root of
the multicast forwarding tree. A downstream interface acts as a router running MLD; therefore, it is
also called router interface.
A device with MLD proxying configured maintains a group membership database, which stores the
group memberships on all the downstream interfaces in this database. Each entry comprises the
multicast address, filter mode, and source list. Such an entry is a collection of members in the same
multicast group on each downstream interface.
A proxy device performs host functions on the upstream interface based on the database. It responds to
the queries according to the information in the database or sends join/leave messages when the
database changes. On the other hand, the proxy device performs router functions on the downstream