Igmp Proxying - HP A6600 Configuration Manual

With the IGMP SSM mapping feature configured, when Router A receives an IGMPv1 or IGMPv2 report,
it checks the multicast group address G carried in the message:
If G is not in the SSM group range, Router A cannot provide the SSM service but can provide the
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ASM service.
• If G is in the SSM group range but no IGMP SSM mappings that correspond to the multicast group
G have been configured on Router A, Router A cannot provide SSM service and drops the message.
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.
The IGMP SSM mapping feature does not process IGMPv3 reports.
For more information about the SSM group range, see

IGMP proxying

In some simple tree-shaped topologies, it is not necessary to configure complex multicast routing protocols,
such as PIM, on the boundary devices. Instead, you can configure IGMP proxying on these devices. With
IGMP proxying configured, the router 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 28 Network diagram for IGMP proxying
Proxy & Querier
Router B
Receiver
Host A
Query from Router A
Report from Router B
Query from Router B
As shown in
Upstream interface—Also called the "proxy interface". A proxy interface is an interface on which
•
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 to the
•
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".
Querier
Router A
Ethernet
Host B
Figure 28, the following types of interfaces are defined on an IGMP proxy device:
"Configuring
PIM domain
Receiver
Host C
Report from Host
Host interface
Router interface
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PIM."