H3C Technologies H3C S12500 Series Switches User Manual
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Admin-scoped zones are divided specific to multicast groups. Zone border routers (ZBRs) form the
boundary of the admin-scoped zone. Each admin-scoped zone maintains one BSR to provide services for
multicast groups within a specific range. Multicast protocol packets, such as assert messages and
bootstrap messages, for a specific group range cannot cross the admin-scoped zone boundary.
Multicast group ranges to which different admin-scoped zones are designated can be overlapped. A
multicast group is valid only within its local admin-scoped zone, and functions as a private group
address.
The global-scoped zone maintains a BSR to provide services for the multicast groups that do not belong
to any admin-scoped zone.
Relationship between admin-scoped zones and the global-scoped zone
The global-scoped zone and each admin-scoped zone have their own C-RPs and BSRs. These devices are
effective only in their respective zones. BSR election and RP election are implemented independently
within each admin-scoped zone. Each admin-scoped zone has its own boundary. The multicast
information cannot cross this border in either direction. A better understanding of the global-scoped
zone and admin-scoped zones should be based on geographical space and group address range.
•
In view of geographical space:
Admin-scoped zones are logical zones specific to particular multicast groups. The multicast
packets of these multicast groups are confined within the local admin-scoped zone and cannot
cross the boundary of the zone.
Figure 46 Relationship between admin-scoped zones and the global-scoped zone in geographic
space
As shown in
, for multicast groups in the same address range, admin-scoped zones must
be geographically separated from one another. A router must not provide services for different
admin-scoped zones. Different admin-scoped zones contain different routers, whereas the
global-scoped zone covers all routers in the PIM-SM/BIDIR-PIM domain. Multicast packets that do
not belong to any admin-scoped zones can be transmitted in the entire PIM-SM/BIDIR-PIM domain.
•
In view of multicast group address ranges:
Each admin-scoped zone serves specific multicast groups. Usually, these addresses have no
intersections; however, they might overlap one another.