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From: mskuhn@faui09.informatik.uni-erlangen.de (Markus Kuhn)
Newsgroups: comp.lang.ada
Subject: OSI on PCs revisited
Message-ID: <mskuhn.665428074@faui09>
Date: 1 Feb 91 17:07:54 GMT
Distribution: comp
Organization: CSD., University of Erlangen, Germany
List-Id: <comp.lang.ada>

Some days ago, I asked here about possibitilies for
OSI connections on asynchronous/start-stop RS-232 lines.

There seems to be some interest in this topic. I got
some suggestions:

1. H.T.Alvestrand suggested me to check X.32 in the CCITT
   Blue Book. I did this. Unfortunately this recommendation
   says only something about synchronous modes on the
   V.24 (= RS-232) interface. The other modes are "for further
   study" (section 4.3.1). Perhaps they intend to use the 
   new HDLC start-stop mode as a further option in the '92 version.
2. Tim Clark reported that in the UK acedemic community, a protocol
   called ATS is used to convert LAP-B in an asynch protocol.
3. Micheal Roe reported that there is a standard in the TCP/IP
   world called 'Serial Line IP' that does exactly what I want.
   So I could run X.25 over TCP/IP.
   He also suggested to modify LLC-1 (also a HDLC subset) for
   asynchronous lines in the same way, HDLC does this.
   This would be the connectionless alternative to my own
   suggestion of an asynch LAP-B.

As I personally prefer X.25, I think, I will implement LAP-B.
But the idea of using LLC-1 sounds also quite interesting
to me. Unfortunately, ATS and Serial Line IP aren't pure OSI so
I don't like them so much. Thank you for your answers.
Any further suggestions?

Has anyone information about the HDLC start-stop mode
(frame format, transparency, etc.)?

Is anyone planning to implement something like this?
Especially in ISODE (would be great)?

Markus Kuhn
CS student