OSI/AS Configuration and Management Manual

NSAP Addressing
OSI/AS Configuration and Management Manual—424119-001
3-6
X25 1980 Versus 1984 Addressing
Figure 3-2 shows the hierarchy of the network addressing domains in Figure 3-1 on
page 3-5.
A single network addressing authority can govern one or more domains. However, for
any domain within the domain hierarchy, there must be only one authority that governs
that domain and its subdomains. For example, the domains shown in Figure 3-1
on
page 3-5 must not intersect. One domain can wholly encompass another domain, but
cannot intersect to include only a part of another domain.
X25 1980 Versus 1984 Addressing
There are two different sets of standards that govern Network Layer addressing for X.25
networks: 1980 address standards and the 1984 extended address standards, as follows:
Figure 3-2. NSAP Network Addressing Domain Hierarchy
1980 address
format
DTE address only (15 decimal digits)
1984 address
format
DTE address
+ address extension (up to 40 hexadecimal digits)
+ address extension type (types are full NSAP, partial NSAP,
non-OSI, reserved)
032CDT .CDD
Global Network
Addressing Domain
Subdomain 2Subdomain 1
System
(NSAP Address)
Subsubdomain
System
(NSAP Address)
System
(NSAP Address)
Subdomain 3
System
(NSAP Address)
Subdomain 4
System
(NSAP Address)