Critique of X.25 (RFC0874)
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2000-Sep-13
< INC-PROJECT, MAP-CRITIQUE.NLS.10, >, 12-Aug-83 11:46 AMW ;;;;
RFC 874 September 1982
A CRITIQUE OF X.25
THE MITRE CORPORATION
The widely touted network interface protocol, "X.25", and
its attendant conceptual framework, the International Standards
Organization's Reference Model for Open System Interconnection
(ISORM), are analyzed and found wanting. The paper is a
companion piece to M82-48, and M82-51.
A CRITIQUE OF X.25
M. A. Padlipsky
According to some sources, the International Standards
Organization's (ISO) "Open System Interconnection" (OSI) effort
has adopted the International Consultative Committee on Telephony
and Telegraphy (CCITT) developed X.25 protocol(s) as its Levels
1-3. ("Loose constructionists" of the ISORM would hold that X.25
is a mechanization of L1-L3 rather than the mechanization, and at
least one British source holds that "we in the U.K. don't believe
that ISO have adopted X.25.") In the U.S. Government arena,
where the author spends much of his time, the Government
Accounting Office (GAO) has suggested that the Department of
Defense (DoD) ought to consider adopting "X.25 networks,"
apparently in preference to networks based on protocols developed
by the DoD-sponsored intercomputer networking research community.
That intercomputer networking research community in turn has,
with a few recent exceptions, adhered to its commitment to the
Oral Tradition and not taken up the cudgels against X.25 in the
open literature, even though X.25 is an object of considerable
scorn in personal communications.
Although the DoD Protocol Standards Technical Panel has
begun to evolve a "Reference Model" different from ISO's for
reasons which will be touched on below, there seems to be a need
to address the deficiencies of X.25 on their own demerits as soon
as possible. Without pretending to completeness*, this paper will
attempt to do just that.
The overall intent is to deal with X.25 in the abstract;
because of who pays the bills, though, a necessary preliminary is
to at least sketch the broad reasons why the DoD in particular
* Various versions of X.25 and ISO documentation were employed;
one incompleteness of note, however, is that no attempt has
been made to do proper bibliographic citation. Another
incompleteness lies in the area of "tutoriality"; that is,
appropriate prior knowledge is assumed on the ...