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MLD SSM mapping
The MLD SSM mapping feature enables you to configure static MLD SSM mappings on the last-hop router
to provide SSM support for receiver hosts that are running MLDv1. The SSM model assumes that the
last-hop router has identified the desired IPv6 multicast sources when receivers join IPv6 multicast groups.
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When a host that runs MLDv2 joins a multicast group, it can explicitly specify one or more multicast
sources in its MLDv2 report.
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A host that runs MLDv1, however, cannot specify multicast source addresses in its MLDv1 report.
You must configure the MLD SSM mapping feature to translate the (*, G) information in the MLDv1
report into (G, INCLUDE, (S1, S2...)) information.
NOTE:
The MLD SSM mapping feature does not process MLDv2 reports.
Figure 77
Network diagram
As shown in
, on the IPv6 SSM network, Host A and Host B runs MLDv1 and Host C runs MLDv2.
To provide SSM service for Host A and Host B, you must configure the MLD SSM mapping feature on
Router A.
With the MLD SSM mapping feature configured, when Router A receives an MLDv1 report, it examines
the IPv6 multicast group address G carried in the message.
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If G is not in the IPv6 SSM group range, Router A cannot provide the SSM service but can provide
the ASM service.
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If G is in the IPv6 SSM group range but no MLD SSM mappings have been configured for the IPv6
multicast group G on Router A, Router A cannot provide SSM service and drops the packet.
•
If G is in the IPv6 SSM group range, and the MLD SSM mappings have been configured on Router
A for multicast group G, Router A translates the (*, G) information in the MLD report into (G,
INCLUDE, (S1, S2...)) information based on the configured MLD SSM mappings and provides SSM
service accordingly.
For more information about the IPv6 SSM group range, see "Configuring IPv6 PIM."
MLDv1 report
MLDv2 report
Router A
Querier
Host A (MLDv1)
IPv6 SSM
Receiver
Host B (MLDv1)
Receiver
Host C (MLDv2)
Receiver
