Igmp Proxying - HP MSR ASM Configuration Manual

If G is in the SSM group range and the IGMP SSM mappings have been configured on Router A for
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multicast group G, Router A translates the (*, G) information in the IGMP report into (G, INCLUDE,
(S1, S2...)) information based on the configured IGMP SSM mappings and provides SSM service
accordingly.
NOTE:
The IGMP SSM mapping feature does not process IGMPv3 reports.
For more information about the SSM group range, see "Configuring PIM."

IGMP proxying

In a simple tree-shaped topology, it is not necessary to configure complex multicast routing protocols,
such as PIM, on edge devices. Instead, you can configure IGMP proxying on these devices. With IGMP
proxying configured, the device serves as a proxy for the downstream hosts to send IGMP messages,
maintain group memberships, and implement multicast forwarding based on the memberships. In this
case, each boundary device is a host but no longer a PIM neighbor to the upstream device.
Figure 14 IGMP proxying
As shown in
Upstream interface—Also called the "proxy interface." A proxy interface is an interface on which
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IGMP proxying is configured. It is in the direction toward the root of the multicast forwarding tree.
An upstream interface acts as a host that is running IGMP. Therefore, it is also called the "host
interface."
Downstream interface—An interface that is running IGMP and is not in the direction toward the
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root of the multicast forwarding tree. A downstream interface acts as a router that is running IGMP.
Therefore, it is also called the "router interface."
An IGMP proxy device maintains a group membership database, which stores the group memberships
on all the downstream interfaces. 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.
Figure 14, an IGMP proxy device has the following types of interfaces:
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