RFC 2126 (rfc2126) - Page 3 of 25

ISO Transport Service on top of TCP (ITOT)

RFC 2126              ISO Transport on top of TCP             March 1997


   one preserves the services offered by a particular layer (the
   Service-Provider) then the Service-User at that layer is completely
   unaffected by changes in the underlying layers or by the protocol
   used within the layer.

   This document defines a Transport Service which appears to be
   identical to the Services and Interfaces offered by the ISO Transport
   Service Definition [ISO8072], but which will in fact implement the
   ISO Transport Protocol [ISO8073] on top of TCP/IP (IPv4 or IPv6),
   rather than the ISO Network Service [ISO8348].

   The basis of this document is STD35, RFC 1006 [RFC 1006] written by
   Marshall T. Rose and Dwight E. Cass and it defines two transport
   classes of service.  Transport Class 0 refines and supersedes the
   RFC 1006 protocol and is aimed at preserving the RFC 1006 installed
   base.  Transport Class 2 defines a number of new features which are
   not provided in RFC 1006, such as independence of Normal and Expedited
   Data channels and Explicit Transport Disconnection. These new
   features are largely based on RFC 1859 [RFC 1859] and extend the
   applicability of RFC 1006 to new groups of applications.

   This document specifies changes to the standards mentioned above and
   must be read in the context of the above mentioned standards. It will
   not be meaningful on its own.

   The 'well known' TCP port 102 is reserved for hosts which implement
   the Protocol described in this document. Note that the Protocol does
   not mandate the use of TCP port 102 for all connections.

2. The Model

   This section describes the differences between the model used by the
   ISO Transport and that described in this document.

2.1 ISO Transport Model

   The ISO 8072 standard describes the ISO Transport Service Definition
   (TS).  The ISO Transport Service Definition describes the services
   offered by the Transport Service Provider and the interfaces used to
   access these services.

   The ISO 8073 standard describes the ISO Transport Protocol
   Specification (TP).  The ISO Transport Protocol specifies common
   encoding rules and a number of classes of transport protocol
   procedure which can be used with different network Quality of
   Service.





Pouffary & Young            Standards Track