
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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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)



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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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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.

















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