MLD SSM mapping

An MLDv2 host can explicitly specify multicast sources in its MLDv2 reports. From the reports, the MLD device can obtain the multicast source addresses and directly provide the SSM service. However, an MLDv1 host cannot specify multicast sources in its MLDv1 reports.

The MLD SSM mapping feature enables the MLD device to provide SSM support for MLDv1 receiver host. The device translates (*, G) in MLDv1 reports into (G, INCLUDE, (S1, S2...)) based on the configured MLD SSM mappings.

As shown in Figure 101, Host A and Host B on the IPv6 SSM network run MLDv1, and Host C runs MLDv2. To provide the SSM service for Host A and Host B, you must configure the MLD SSM mapping feature on Device A.

After MLD SSM mappings are configured, Device A checks the IPv6 multicast group address G carried in the message, and performs the following operations:

• If G is not in the IPv6 SSM group range, Device A provides the ASM service.

• If G is in the IPv6 SSM group range but does not match any MLD SSM mapping, Device A drops the report.

• If G is in the IPv6 SSM group range and matches MLD SSM mappings, Device A translates (*, G) in the report to (G, INCLUDE, (S1, S2...)) to provide SSM services.

	NOTE: The MLD SSM mapping feature does not process MLDv2 reports.

For more information about the IPv6 SSM group ranges, see "Configuring IPv6 PIM."