Network Working Group ANSI
Request for Comments: 982 April 1986
 Guidelines for the Specification of the Structure of the
 Domain Specific Part (DSP) of the ISO Standard NSAP Address
 ANSI Working Document X3S3.3/85-258
Status of This Memo
 The following is a RFC edition of the ANSI "Guidelines for the
 Specification of the Structure of the Domain Specific Part (DSP) of
 the ISO Standard NSAP Address". It should be understood that this
 ANSI working document is in a draft state and subject to change.
 These Guidelines are an important prerequirement to allow IP
 addressing within the ISO connectionless protocol (CLNS), which
 itself is necessary to allow the coexistance of the IP and the CLNS
 in the Arpanet attached gateways.
 A RFC to specify a suitable IP addressing method for ISOgrams is
 currently worked on in Internet Task Forces and should be expected as
 an RFC shortly.
 This RFC is for informational purposes only and it's distribution
 is unlimited. It does not specify a standard for the Arpa-Internet.
 Hans-Werner Braun (HWB@GW.UMICH.EDU)
 University of Michigan
RFC 982 April 1986
ANSI Guidelines
TITLE: GUIDELINES FOR THE SPECIFICATION OF THE STRUCTURE OF THE
 DOMAIN SPECIFIC PART (DSP) OF THE ISO STANDARD NSAP ADDRESS
STATUS: X3S3.3 WORKING DRAFT
Introduction
 There is a substantial amount of interest in providing guidance to
 private address administration authorities on preferred formats and
 semantics for the Domain Specific Part (DSP) of an NSAP address. In
 particular it is felt that use of a limited number of preferred DSP
 formats would allow organizations to easily use intermediate and end
 systems from a variety of suppliers. This technical report specifies
 the way in which the DSP may be constructed so as to facilitate
 efficient address assignment.
1. Scope and Field of Application
 This Technical Report specifies a recommended syntax and
 interpretation for the Domain Specific Part of an NSAP address. NSAP
 Address Administration Authorities are urged to use this format when
 the equipment comprising an addressing domain is of a heterogeneous
 nature.
2. References
 ISO 6523 Data Interchange - Structure for the
 identification of Organizations
 ISO 7498 Information Processing Systems - Open Systems
 Interconnection - Basic Reference Model
 ISO 8348 Information Processing Systems - Data
 Communications - Network Service Definition
 ISO DIS 8348/DAD2 Information Processing Systems - Data
 Communications - Addendum to the Network
 Service Definition Covering Network Layer
 Addressing
 ISO DIS 8802 Information Processing Systems - Data
 Communications - Local Area Networks
 ECMA TR/20 Layer 4 to 1 Addressing
RFC 982 April 1986
ANSI Guidelines
3. Definitions
 (This section to be suppled)
4. Abbreviations
 (This section to be supplied)
5. Addressing Principles
 This section provides a summary of the major points contained in DIS
 8348/DAD2, as they are relevant to this technical report.
 Network addresses are defined to be hierarchical. An authority may
 either assign a complete address, or else may identify a subdomain of
 its own addressing domain within which addresses may be further
 assigned by an identified authority for the subdomain. This is done
 in such a way that all addresses are unique.
 When an authority identifies a subdomain, this creates in effect a
 prefix which applies to all addresses assigned within the subdomain.
 Certain methods of assigning authority are recognized within the body
 of DIS 8348/DAD 2. These take account of existing addressing
 standards such as X.121. The abstract structure of an address is
 shown in Figure 1.
RFC 982 April 1986
ANSI Guidelines
 +---------------------------+---------------------------+
 I I I
 I I D P I D S P I
 I I I
 +---------------------------+---------------------------+
 : :
 : :
 V V
 +-----+---------------------+
 I I I
 I AFI I I D I I
 I I I
 +-----+---------------------+
 Figure 1: NSAP Address Structure
 The components of this structure are as follows.
 IDP: Initial Domain Part
 This is the part of the address whose entire content is
 standardized. It consists of two parts, the AFI and the IDI.
 AFI: Authority and Format Identifier
 This specifies the format of the IDI, the authority responsible
 for allocating IDI values, and the syntax of the DSP.
 IDI: Initial Domain Identifier
 This identifies the subdomain from which DSP values are allocated,
 and the authority responsible for allocating the values.
 DSP: Domain Specific Part
 The contents and semantics of the DSP are not specified in DIS
 8348/DAD2. Its abstract syntax is however defined by the AFI. In
 most cases, this means that the DSP abstract syntax can be either
 binary or decimal.
 IDI formats specified in DIS 8348/DAD2 identify a number of
 authorities for IDI allocation. These are:
 1. X.121 (Public data network numbering)
 2. F.69 (Telex numbering)
RFC 982 April 1986
ANSI Guidelines
 3. E.163 (Telephone numbering)
 4. E.164 (ISDN numbering)
 5. ISO DCC (Geographical address assignment under ISO authority.
 A subset of the DCC values used in X.121 have been used to
 designate the national addressing authorities)
 6. ISO 6523-ICD (Non-geographic address assignment under ISO
 authority, using the International Code Designators according
 to ISO 6523)
 7. Local (the IDI is null and the entire address is contained in
 the DSP).
6. Analysis
 (This section to be supplied)
7. Recommendations
 7.1 X.121 DSP format guidelines
 Description of Binary syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 2 or less octets is an NSAP
 selector. A DSP between 3 and 9 octets is interpreted in the
 manner described below.
 The length of the subnetwork identification is fixed at two
 octets (16 bits). The assignment of subnetwork
 identifications is under the control of the administering
 authority for the private domain, except that the value with
 both octets hex "FF" is reserved to indicate that the
 subnetwork is not explicitly identified.
 The length of the subnetwork address may be up to six octets,
 and is determined by the DSP length minus three octets. For
 subnetworks using DIS 8802 MAC addressing, this field consists
 of the octets of the MAC address in the same order as they are
 defined in DIS 8802.
 The NSAP selector occupies a single octet.
RFC 982 April 1986
ANSI Guidelines
 Description of Decimal syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 8 or less decimal digits is
 an NSAP selector. A DSP between 8 and 23 decimal digits is
 interpreted in the manner described below.
 The length of the subnetwork identification is fixed at five
 decimal digits. The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that a value of "99999" is reserved to
 indicate that the subnetwork is not explicitly identified.
 The length of the subnetwork address may be up to fifteen
 decimal digits, and is determined by the DSP length minus eight
 decimal digits.
 The NSAP selector occupies three decimal digits.
 7.2 ISO DCC DSP format guidelines
 Description of Binary syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. The length of the DSP is between 6 and 12 octets.
 The first three octets identify an organization which has been
 designated as an addressing authority. This authority is
 responsible for assigning values to the remainder of the DSP.
 The length of the subnetwork identification is fixed at two
 octets (16 bits). The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that the value with both octets hex "FF"
 is reserved to indicate that the subnetwork is not explicitly
 identified.
 The length of the subnetwork address may be up to six octets,
 and is determined by the DSP length minus three octets. For
 subnetworks using DIS 8802 MAC addressing, this field consists
 of the octets of the MAC address in the same order as they are
 defined in DIS 8802.
 The NSAP selector occupies a single octet.
RFC 982 April 1986
ANSI Guidelines
 Description of Decimal syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. The length of the DSP is between 14 and 29 decimal
 digits.
 The first six digits identify an organization which as been
 designated as an addressing authority. This authority is
 responsible for assigning values to the remainder of the DSP.
 The length of the subnetwork identification is fixed at five
 decimal digits. The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that a value of "99999" is reserved to
 indicate that the subnetwork is not explicitly identified.
 The length of the subnetwork address may be up to fifteen
 decimal digits, and is determined by the DSP length minus eight
 decimal digits.
 The NSAP selector occupies three decimal digits.
 7.3 F.69 DSP format guidelines
 Description of Binary syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 2 or less octets is an NSAP
 selector. A DSP between 3 and 9 octets is interpreted in the
 manner described below. Interpretation of a DSP greater than 9
 octets in length is not specified in this report.
 The length of the subnetwork identification is fixed at two
 octets (16 bits). The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that the value with both octets hex "FF"
 is reserved to indicate that the subnetwork is not explicitly
 identified.
 The length of the subnetwork address may be up to six octets,
 and is determined by the DSP length minus three octets. For
 subnetworks using DIS 8802 MAC addressing, this field consists
 of the octets of the MAC address in the same order as they are
 defined in DIS 8802.
RFC 982 April 1986
ANSI Guidelines
 The NSAP selector occupies a single octet.
 Description of Decimal syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 8 or less decimal digits is
 an NSAP selector. A DSP between 8 and 23 decimal digits is
 interpreted in the manner described below. Interpretation of a
 DSP greater than 23 decimal digits in length is not specified
 in this report.
 The length of the subnetwork identification is fixed at five
 decimal digits. The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that a value of "99999" is reserved to
 indicate that the subnetwork is not explicitly identified.
 The length of the subnetwork address may be up to fifteen
 decimal digits, and is determined by the DSP length minute
 eight decimal digits.
 The NSAP selector occupies three decimal digits.
 7.4 E.163 DSP format guidelines
 Description of Binary syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 2 or less octets is an NSAP
 selector. A DSP between 3 and 9 octets is interpreted in the
 manner described below. Interpretation of a DSP greater than 9
 octets in length is not specified in this report.
 The length of the subnetwork identification is fixed at two
 octets (16 bits). The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that the value with both octets hex "FF"
 is reserved to indicate that the subnetwork is not explicitly
 identified.
 The length of the subnetwork address may be up to six octets,
 and is determined by the DSP length minus three octets. For
 subnetworks using DIS 8802 MAC addressing, this field consists
 of the octets of the MAC address in the same order as they are
 defined in DIS 8802.
RFC 982 April 1986
ANSI Guidelines
 The NSAP selector occupies a single octet.
 Description of Decimal syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 8 or less decimal digits is
 an NSAP selector. A DSP between 8 and 23 decimal digits is
 interpreted in the manner described below. Interpretation of a
 DSP greater than 23 decimal digits in length is not specified
 in this report.
 The length of the subnetwork identification is fixed at five
 decimal digits. The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that a value of "99999" is reserved to
 indicate that the subnetwork is not explicitly identified.
 The length of the subnetwork address may be up to fifteen
 decimal digits, and is determined by the DSP length minus eight
 decimal digits.
 The NSAP selector occupies three decimal digits.
 7.5 E.164 DSP format guidelines
 Description of Binary syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 2 or less octets is an NSAP
 selector. A DSP between 3 and 9 octets is interpreted in the
 manner described below. Interpretation of a DSP greater than 9
 octets in length is not specified in this report.
 The length of the subnetwork identification is fixed at two
 octets (16 bits). The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that the value with both octets hex "FF"
 is reserved to indicate that the subnetwork is not explicitly
 identified.
 The length of the subnetwork address may be up to six octets,
 and is determined by the DSP length minus three octets. For
 subnetworks using DIS 8802 MAC addressing, this field consists
 of the octets of the MAC address in the same order as they are
 defined in DIS 8802.
RFC 982 April 1986
ANSI Guidelines
 The NSAP selector occupies a single octet.
 Description of Decimal syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. If DSP is present, a DSP of 8 or less decimal digits is
 an NSAP selector. A DSP between 8 and 23 decimal digits is
 interpreted in the manner described below. Interpretation of a
 DSP greater than 23 decimal digits in length is not specified
 in this report.
 The length of the subnetwork identification is fixed at five
 decimal digits. The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that a value of "99999" is reserved to
 indicate that the subnetwork is not explicitly identified.
 The length of the subnetwork address may be up to fifteen
 decimal digits, and is determined by the DSP length minus eight
 decimal digits.
 The NSAP selector occupies three decimal digits.
 7.6 ISO 6523-ICD DSP format guidelines
 Description of Binary syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. The length of the DSP is between 5 and 11 octets.
 The first two octets identify an organization which has been
 designated as an addressing authority. This authority is
 responsible for assigning values to the remainder of the DSP.
 The length of the subnetwork identification is fixed at two
 octets (16 bits). The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that the value with both octets hex "FF"
 is reserved to indicate that the subnetwork is not explicitly
 identified.
 The length of the subnetwork address may be up to six octets,
 and is determined by the DSP length minus three octets. For
RFC 982 April 1986
ANSI Guidelines
 subnetworks using DIS 8802 MAC addressing, this field consists
 of the octets of the MAC address in the same order as they are
 defined in DIS 8802.
 The NSAP selector occupies a single octet.
 Description of Decimal syntax
 The length of the DSP can be determined since the total address
 length is known, and the IDP has fixed length for any given AFI
 value. The length of the DSP is between 12 and 27 decimal
 digits.
 The first four digits identify an organization which has been
 designated as an addressing authority. This authority is
 responsible for assigning values to the remainder of the DSP.
 The length of the subnetwork identification is fixed at five
 decimal digits. The assignment of subnetwork identifications
 is under the control of the administering authority for the
 private domain, except that a value of "99999" is reserved to
 indicate that the subnetwork is not explicitly identified.
 The length of the subnetwork address may be up to fifteen
 decimal digits, and is determined by the DSP length minus eight
 decimal digits.
 The NSAP selector occupies three decimal digits.
 7.7 Local DSP format guidelines
 No recommendations made.