Thread View: comp.protocols.iso
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Started by Markus Kuhn
Mon, 04 Feb 1991 11:48
OSI on asynch PC lines revisited
Author: Markus Kuhn
Date: Mon, 04 Feb 1991 11:48
Date: Mon, 04 Feb 1991 11:48
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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 in the start-stop-mode addendum (1990). 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 detailed 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
Re: OSI on asynch PC lines revisited
Author: Erik Naggum
Date: Mon, 04 Feb 1991 18:52
Date: Mon, 04 Feb 1991 18:52
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In article <mskuhn.665668137@faui09> mskuhn@faui09.informatik.uni-erlangen.de (Markus Kuhn) writes: > 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. The start-stop mode lower layer of X.25 was issued as an "expedited procedure" recommendation or somesuch. I believe it's X.32 bis. CCITT has opted for a speedy procedure for most of the interesting things. [FX].435, for instance. You don't have to wait until 1992 for all the neat things they decide to recommend. -- [Erik Naggum] <enag@ifi.uio.no> Naggum Software, Oslo, Norway <erik@naggum.uu.no>
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