Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!CUNYVM.CUNY.EDU!af%sei.ucl.ac.be
From: af%sei.ucl.ac.be@CUNYVM.CUNY.EDU ("Alain FONTAINE ", Postmaster - NAD)
Newsgroups: comp.protocols.tcp-ip
Subject: X.400 on TCP
Message-ID: <890915.163451.+0200.af@sei.ucl.ac.be>
Date: 18 Sep 89 09:50:13 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 33

It seems that one  of the first practical results of  the OSI (1) effort
will be  the deployment of Message  Handling Systems based on  the X.400
CCITT recommendations (2). The MHS is defined at layer 7 ; in strict OSI
logic, it is  expected to use the services of  an OSI presentation layer
(which I was told it does *not*, even in a full OSI setup :_) ).

In  order to  use some  current network  infrastructure, operation  of a
X.400 MHS  on top of  TCP (which,  when applying the  OSI RM to  the DDN
suite (3), generally  ends up at layer  4, but who needs layers  5 and 6
when  one has  TCP :-)  )  will probably  be commonplace  in the  (near)
future.

The question : is there any work going on to define a standard way to do
this, in order to allow implementations of X.400 conforming to the CCITT
recommendations,  operating on  TCP  implementations  conforming to  the
relevant RFC's, to interoprate ? In one word, the reverse of RFC 1090.

Thank you in advance for any relevant comments. /AF

(1) please,  no wasting of  network ressources and readers  time arguing
about OSI vs ISO, or about the distinction between the RM and the actual
protocols, etc.
(2) please etc etc about the OSIness  of the CCITT, or the fact that one
should perhaps write X.4xx, etc.
(3) please ....... about the correctness of doing so.

Alain FONTAINE                       +--------------------------------+
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