H3C Technologies H3C S10500 Series Switches - Manual (Page 384)

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packets that do not belong to any admin-scope zones can be transmitted in the entire IPv6 PIM-SM/IPv6
BIDIR-PIM domain.
2. Multicast group address Scope field
As shown in Figure 102 , the Scope field in each IPv6 multicast group address indicates the admin-scope
zone the corresponding multicast group belongs to.
Figure 102 IPv6 multicast address format
The admin-scope zone range increases with the value of the Scope field. For example, value E indicates
IPv6 global scope, which contains other admin-scope zones with the Scope field values smaller than E.
Possible values of the Scope field are given in Table 12 .
Table 12 Values of the Scope field
Value Meaning Remarks
0, F Reserved —
1 Interface-local scope —
2 Link-local scope —
3 Subnet-local scope IPv6 admin-scope zone
4 Admin-local scope IPv6 admin-scope zone
5 Site-local scope IPv6 admin-scope zone
6, 7, 9 through D Unassigned IPv6 admin-scope zone
8 Organization-local scope IPv6 admin-scope zone
E Global scope IPv6 global-scope 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. You can implement the SSM model by
leveraging part of the IPv6 PIM-SM technique. 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. This model does not require RP or RPT, and it does not require
a source registration process for the purpose of discovering IPv6 multicast sources in other IPv6 PIM
domains.
The working mechanism of IPv6 PIM-SSM is summarized as follows:
• Neighbor discovery