Encoding Network Addresses to Support Operation over Non-OSI Lower Layers
RFC 1277

 
Document Type RFC - Proposed Standard (November 1991; No errata)
Last updated 2013-03-02
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Network Working Group                            S.E. Hardcastle-Kille
Requests for Comments 1277                   University College London
                                                         November 1991

                      Encoding Network Addresses
            to support operation over non-OSI lower layers

Status of this Memo
    This RFC specifies an IAB standards track protocol for the
    Internet community, and requests discussion and suggestions for
    improvements.  Please refer to the current edition of the ``IAB
    Official Protocol Standards'' for the standardization state and
    status of this protocol.  Distribution of this memo is unlimited.
Abstract

    The OSI Directory specifies an encoding of Presentation Address,
    which utilises OSI Network Addresses as defined in the OSI
    Network Layer standards [CCI88] [ISO87a].  The OSI Directory, and
    any OSI application utilising the OSI Directory must be able use
    these Network Addresses to identify end systems.  Currently, OSI
    applications are often run over lower layers other than the OSI
    Network Service.  It is neither reasonable nor desirable for
    groups wishing to investigate and use OSI Applications in
    conjunction with the OSI Directory to be dependent on a global
    OSI Network Service.  This document defines a new network address
    format, and rules for using some existing network address
    formats.  The scope of this document is:

1.  Any TCP/IP network supporting COTS using RFC 1006.

2.  Any mapping of COTS onto X.25 (usually X.25(80)), where X.25 is
    not used to provide CONS (i.e., only DTE and not Network address
    is carried).

    The approach could also be extended to use with other means of
    providing COTS (or CLTS). It is not appropriate for use where
    CONS or CLNS is used to provide COTS (or CLTS).



RFC 1277           Encoding Network Addresses            November 1991

1  Introduction

The OSI Directory specifies an encoding of Presentation Address, which
utilises OSI Network Addresses as defined in the OSI Network Layer
standards [CCI88] [ISO87a].  The OSI Directory, and any OSI
application utilising the OSI Directory must be able use these Network
Addresses to identify end systems.
Currently, OSI applications are often run over lower layers other than
the OSI Network Service.  It is neither reasonable nor desirable for
groups wishing to investigate and use OSI Applications in conjunction
with the OSI Directory to be dependent on a global OSI Network
Service.  This RFCdefines mechanisms to encode addressing information
within Network Addresses, in order to support this type of working.
In particular, support is defined for RFC 1006 mapping of COTS onto
TCP/IP and COTS mapped onto X.25(1980) [RC87, CCI80].

Where an OSI application is run over CLNS on the internet, the NSAP
Guidelines of RFC 1237 should be followed [CGC91].
This document must be read in the context of ISO 8348 Addendum 2
[ISO87b].  It will not be meaningful on its own.

1.1  Historical Note

This document was originally published as UCL Research Note RN/89/13
and as a project THORN internal document [Kil89].  It was devised in
response to two projects which faced this requirement, and was agreed
as a common approach.  The projects were:

 o  The THORN project, which is an Esprit Project building an OSI
    Directory [SA88].

 o  The ISODE project [Ros90], and in particular the QUIPU directory
    being developed at UCL [Kil88].

The proposal has been implemented, and the viability of the solution
demonstrated.

Hardcastle-Kille                                                Page 1



RFC 1277           Encoding Network Addresses            November 1991

2  Problem Statement

When utilising the OSI Directory, the OSI location of an End System
will be determined by a Network Address, which is taken from a
Presentation Address, looked up in the OSI Directory.
OSI applications are currently operated over the following lower
layers.

 o  An international X.25 network, which routes on the basis of X.121
    addresses.  By and large this is X.25(80), but some parts are now
    X.25(84) and will carry Network Addresses as user data.  OSI
    Transport is mapped onto the variant of X.25 which is available.

 o  Large private X.25 networks, which do not have DNICs, but are
    otherwise similar to the previous (in particular Janet).

 o  Isolated networks running Connection Oriented Network Service
    (e.g., Pink Book Ethernets).

 o  Isolated networks running Connectionless Network Service (e.g.,
    MAP LANs).

 o  The Connectionless Network Service Protocol (CLNP) pilot,
    currently taking place in the NSFNet and NORDUNet communities.

 o  Isolated TCP/IP LANs, utilising RFC 1006 to support the OSI
    Transport Service[RC87].

 o  The DARPA/NSF Internet, using RFC 1006.

In general, these systems need to be interconnected by the use of
transport bridging or application relaying.  Operation of transport
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