H3C Technologies H3C S12500 Series Switches - Manual (Page 396)

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Figure 107 IPv6 multicast address format
The admin-scoped zone range increases with the value of the Scope field. For example, value E
indicates IPv6 global-scoped, which contains other admin-scoped zones with the Scope field
values smaller than E. Possible values of the Scope field are given in Table 26 .
Table 26 Values of the Scope field
Value Meaning Remarks
0, F Reserved N/A
1 Interface-local scope N/A
2 Link-local scope N/A
3 Subnet-local scope IPv6 admin-scoped zone.
4 Admin-local scope IPv6 admin-scoped zone.
5 Site-local scope IPv6 admin-scoped zone.
6, 7, 9 through D Unassigned IPv6 admin-scoped zone.
8 Organization-local scope IPv6 admin-scoped zone.
E Global scope IPv6 global-scoped zone.
IPv6 PIM-SSM overview
The source-specific multicast (SSM) model and the any-source multicast (ASM) model are opposites. The
ASM model includes the IPv6 PIM-DM and IPv6 PIM-SM modes. The SSM model can be implemented by
leveraging part of the IPv6 PIM-SM technique, and it is also called IPv6 PIM-SSM.
The SSM model provides a solution for source-specific multicast. It maintains the relationships between
hosts and routers through MLDv2.
In actual application, MLDv2 and part of IPv6 PIM-SM technique is adopted to implement the SSM model.
In the SSM model, receivers know exactly where an IPv6 multicast source is located by using
advertisements, consultancy, and so on. Therefore, no RP is needed, no RPT is required, and no source
registration process is needed for the purpose of discovering IPv6 multicast sources in other IPv6 PIM
domains.
In IPv6 PIM-SSM, the term "channel" refers to an IPv6 multicast group, and the term "channel
subscription" refers to a join message.
The operating mechanism of IPv6 PIM-SSM is summarized as follows:
• Neighbor discovery
• DR election