3com S7906E 설치 설명서

 

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The MLD SSM mapping feature allows you to configure static MLD SSM mappings on the last hop 

router to provide SSM support for receiver hosts running MLDv1. The SSM model assumes that the last 

hop router is aware of the desired IPv6 multicast sources when receivers join IPv6 multicast groups. 

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When a host running MLDv2 joins a multicast group, it can explicitly specify one or more multicast 

sources in its MLDv2 report. 

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A host running MLDv1, however, cannot specify multicast source addresses in its MLDv1 report. In 

this case, you need to configure the MLD SSM mapping feature to translate the (*, G) information in 

the MLDv1 report into (G, INCLUDE, (S1, S2...)) information. 

Figure 1-5 Network diagram for MLD SSM mapping 

MLDv1 report

MLDv2 report

Router A

Host A (MLDv1)

IPv6 SSM

Host B (MLDv1)

Host C (MLDv2)

 

 

As shown in 

, on an IPv6 SSM network, Host A and Host B are running MLDv1 and Host C is 

running MLDv2. To provide SSM service for all the hosts while it is infeasible to run MLDv2 on Host A 

and Host B, you need to configure the MLD SSM mapping feature on Router A. 

With the MLD SSM mapping feature configured, when Router A receives an MLDv1 report, it checks 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 the ASM 

service. 

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If G is in the IPv6 SSM group range but no MLD SSM mappings corresponding to the IPv6 

multicast group G have been configured on Router A, Router A cannot provide SSM service and 

drops the packet.  

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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.