3Com S7906E Configuration Manual page 1034

Figure 1-7 Relationship between admin-scope zones and the global scope zone in geographic space
As shown in Figure 1-7, for multicast groups in the same address range, admin-scope zones must be
geographically separated from one another. Namely, a router must not serve different admin-scope
zones. In other words, different admin-scope zones contain different routers, whereas the global scope
zone covers all routers in the PIM-SM domain. Multicast packets that do not belong to any admin-scope
zones can be transmitted in the entire PIM-SM domain.
2) In terms of multicast group address ranges
Each admin-scope zone serves specific multicast groups. Usually, these addresses have no
intersections; however, they may overlap one another.
Figure 1-8 Relationship between admin-scope zones and the global scope zone in group address
ranges
In Figure 1-8, the group address ranges of admin-scope 1 and 2 have no intersection, whereas the
group address range of admin-scope 3 is a subset of the address range of admin-scope 1. The group
address range of the global scope zone covers all the group addresses other than those of all the
admin-scope zones. That is, the group address range of the global scope zone is G-G1-G2. In other
words, there is a supplementary relationship between the global scope zone and all the admin-scope
zones in terms of group address ranges.
1-12