Scope

PNNI routing nodes do not need clean, minty breath when they exchange hellos with their neighbors. The term scope refers to AESA advertisements. By limiting the areas where ATM end system addresses are advertised, scope provides the same benefits as summary addresses.

Why advertise source AESAs to areas that have no demand for connections to these end systems? Scope is typically discussed at the UNI interface. The UNI 4.0 specification outlines 15 scope levels that correspond to certain hierarchy levels in PNNI. This scope-to-hierarchy mapping ensures that AESAs are advertised to only a predefined hierarchy level. Table 9-3 shows this mapping.

Table 9-3. Scope Mapping

UNI Scope	PNNI Hierarchy Level
1 to 3	96
4 to 5	80
6 to 7	72
8 to 10	64
11 to 12	48
13 to 14	32
0	Global (0)