    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

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    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

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    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.

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          +---------------------------+---------------------------+
          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)

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          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.

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          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.

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          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.

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             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.

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             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.

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             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

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             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.

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