Current NSAP Allocation Formats

ANSI Format

ANSI is the standards body that controls the United States Data Country Code (DCC) 840. They have defined the first three octets of the DSP to be an Organization Identifier, leaving the other 14 octets (the PAP) to be defined by each controlling organization. ANSI may be reached at the following address:

	NOTE: ANSI defines a recommended PAP structure for their NSAP space. It's syntax may be obtained by writing to the above address.

AFNOR Format

AFNOR (Association Francaise de NORmalisation) is the standards body that controls the French Data Country Code (DCC) 250. Like ANSI, they have defined the first three octets of the DSP to be an Organization Identifier, leaving the other 14 octets (the PAP) to be defined by each controlling organization. AFNOR describes their addressing format in its document, X 60-000. AFNOR may be reached at the following address:

United States GOSIP

The United States GOSIP format, whose administration authority is NIST, is to be used by United States Government agencies for their OSI networks. NIST will also assign NSAPs from their NSAP space to non-government organizations upon request.

This format is a good example of how the various PAP fields may be used to create a well defined NSAP space that can evolve over time. U.S. GOSIP has taken a domain/area approach to routing and has defined the entire structure of the DSP. Because of this, they have also added some fields that will allow their structure to change over time, namely the DFI and Rsv fields.

To obtain more information about the U.S. GOSIP NSAP structure, contact:

A more complete discussion of this addressing format may be found in U.S. Government OSI Profile Specification Version 2.

This document is produced by the National Institute of Standards and Technology, USA (NIST). It should be available through Omnicom or NIST.

United Kingdom GOSIP

The United Kingdom GOSIP program, like ANSI, has chosen the Data Country Code format for their IDP. GDP values are provided by the Central Computer and Telecommunications Agency (CCTA), and functions in a similar fashion as U.S. GOSIP's Admin field. The GDSP is undefined and is left up to the controlling organization (identified by the GDP) as to its structure. U.K. GOSIP recommends that the following fields be defined as the rightmost portion of the GDSP:

The Subnetwork Identifier may identify a physical subnetwork, or an area. The Subnetwork Address field may contain a real subnetwork address, such as a MAC or X.121 address, or a virtual end system identifier that uniquely identifies the end system for the specified Subnet ID. HP recommends that the NSel field be set to 01.

A more complete discussion of this addressing format may be found in U.K. Government OSI Profile Specification Version 3.1 and Procedure for Obtaining a U.K. Government Domain Part (GDP) under the ISO DCC Addressing Scheme.

These documents are produced by the Central Computer and Telecommunications Agency, UK. They should be available through Omnicom International, Ltd. or CCTA.

MAP/TOP 3.0

Unlike ANSI and AFNOR, which defined an AP and left the PAP undefined, MAP/TOP has defined a general format for the PAP portion. Their PAP may be used with any valid AP.

MAP/TOP has decided to use subnetworks as their level of routing rather than areas. This is more in line with present ARPA routing procedures than the upcoming ISO routing protocols. MAP/TOP does recommend that the customary 2/6/1 field lengths be used for the PAP portion to allow easy migration to area-based routing in the future.

A more complete discussion of this addressing format may be found in Manufacturing Automation Protocol Specification, Version 3.0, available from the MAP/TOP users group: