Xref: utzoo comp.unix.xenix:3394 comp.dcom.lans:1839 Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!bu-cs!purdue!decwrl!sun!pitstop!sundc!seismo!uunet!munnari!ditmela!george From: george@ditmela.oz (George michaelson) Newsgroups: comp.unix.xenix,comp.dcom.lans Subject: Re: 386 UNIX on OpenNet Message-ID: <2430@ditmela.oz> Date: 21 Sep 88 07:50:00 GMT References: <1988Sep20.183604.2240@utzoo.uucp> Organization: CSIRO Division of Information Technology, Australia Lines: 59 From article <1988Sep20.183604.2240@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): > In article <1537@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes: >>As an aside, what is the history between the split between OSI and DOD? > > Well, *very* concisely, the TCP/IP protocols are a bit old and have some the split predates even TCP/IP I suggest. ARPA was designed as a datagram service but the CCITT provided services in Europe were/are virtual-circuit based. IMP and the like were being taught as "nasty U.S. ideas we don't want to run" when I learned about X.25 in York. [as an experimental service, in 1980ish] When you rent a leased line, whan you run above it is probably your own buisness, but in the absence of good host-level software you'll take what the PTT provides. If PTT's had pushed datagram at their customers renting leased lines, perhaps we'd all be in the same bathtub. By the time public networks got off the ground, the split was already history. ISO/CCITT transport must be post-1982 because I recall working with ECMA specs for transport, and then seeing them massaged into the BSI/IEEE submission (to DP state I guess). At that stage, very few people in the UK had ethernet, what was available was researchy and slow and nasty. There was already in place a GEC based packet switching VC network (SERCnet later to become JANET) running X.25 and like-minded protocols on top. -this was only just starting to squeeze out the old point-to-point links from various uni's to computer centres and the like. for ISO class 4, the early documents may have had some discussion about why they used time based rather than hop based TTL. are there more important differences? Many people were either using VMS version 2.x or V7 unix, and neither come as-is with TCP/IP, but did have free/cheap X.25 solutions available. perhaps if TCP had been visible on 360's, ICL 2900's, and DEC-10's around the 70's it would have looked a better option, but when people in the UK started writing network code for their central facilities, X.25 aligned stuff came out. So a combination of lack of availability, funded nets with non DoD protocols, PTT intransigence and NIH seem to be likely. Why then did the PTT's (who tend to dominate the standards process, certainly for the CCITT and I would expect also the ISO committees outside of the US/UK) reject the datagram model? did they see an easier path to doing VC stuff, and a better initial return on their investment in H/W and S/W? I was told they opposed multiplexing at the network level because of the established charging pattern (per VC, as well as volume-per-VC) so perhaps money was the final motive, and not architectural preferences. -george -- George Michaelson, CSIRO Division of Information Technology ACSnet: G.Michaelson@ditmela.oz Phone: +61 3 347 8644 Postal: CSIRO, 55 Barry St, Carlton, Vic 3053 Oz Fax: +61 3 347 8987