415
An IPv6 admin-scoped zone with a larger scope field value contains an IPv6 admin-scoped
zone with a smaller scope field value. The zone with the scope field value of E is the IPv6
global-scoped zone.
lists the possible values of the scope field.
Table 13 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-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
The SSM model and the 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. This mode does not required RP or RPT, and does not
require a source registration process for discovering IPv6 multicast sources in other IPv6 PIM
domains.
The operating mechanism of IPv6 PIM-SSM is summarized as follows:
•
•
•
Neighbor discovery
IPv6 PIM-SSM uses the same neighbor discovery mechanism as in IPv6 PIM-SM. For more
information, see "
DR election
IPv6 PIM-SSM uses the same DR election mechanism as in IPv6 PIM-SM. For more information,
see "
."
SPT building
The decision to build an RPT for IPv6 PIM-SM or an SPT for IPv6 PIM-SSM depends on whether the
IPv6 multicast group that the receiver will join falls into the IPv6 SSM group range. The IPv6 SSM
group range that IANA has reserved is FF3x::/32, where x represents any legal address scope.
