<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p>That is a very fascinating piece of history, thanks for writing
that up! I learned a bit.</p>
<p>One hesitates to fully agree with 'obvious', although the
observation is clearly true for the situation.<br>
</p>
<p>On the other hand, in other markets the answer was, in fact, felt
to be quite obvious. In academic settings, some significant
portion switched from Tops-20 to Unix, some running on Ultrix on
VAX hardware, some going straight to Sun. My understanding is
that in both cases, TCP/IP was a bundled part of the product which
you didn't pay extra for. That was the reality on the floor,
whereas it wasn't understood what the cost model was going to be
for OSI.<br>
</p>
<p>There was a percentage that went to VMS, but this was sometimes a
harder sell than Ultrix. I heard of a particularly livid Tops-20
system manager respond to a DEC salesman assurance of forthcoming
features with, "You're asking us to jump out the window on the
promise that you will have the net ready before we hit the ground"<br>
</p>
<div class="moz-cite-prefix">In summary, picking free TCP/IP here
and now over OSI maybe when and maybe cost was an obvious decision
where it was perceived to exist.<br>
</div>
<blockquote type="cite"
cite="mid:2A867F95-6F27-45C0-89B8-802BB6F9B51D@comcast.net">
<hr width="100%" size="2">
<pre class="moz-quote-pre" wrap="">On 11/8/21 1:14 PM, Paul Koning wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">On Nov 8, 2021, at 11:09 AM, Robert Armstrong <a class="moz-txt-link-rfc2396E" href="mailto:bob@jfcl.com"><bob@jfcl.com></a> wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">"when do you send the message". That's actually a question with TCP as
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">well...
You know about the Nagle algorithm, right?
Bob
</pre>
</blockquote>
<pre class="moz-quote-pre" wrap="">
Yes, that's what I was talking about.
As for OSI not producing anything, that's not entirely true. OSPF is clearly derived from at early draft of IS-IS, however much its authors may want to hide that fact.
The people in the DECnet architecture group (I was one, though junior) certainly went through a whole lot of hindsight review over the OSI vs. TCP history. It's always easy to say the right answer was obvious when you look back a decade or three later after everything was settled. At the time, it wasn't quite so obvious.
The US centric vs. international thing is clearly a piece of the puzzle. Another piece is that, other than for academic and military use, the ARPAnet wasn't really available. Once it opened up for commercial use the matter was settled, but that didn't happen until later (around the time of the invention of the world wide web). So at the time Phase V was being created, the world had lots of small islands -- individual company in-house networks -- with very little interconnectivity among them. And in much of the world, what cross-company connectivity existed was, often by law, provided by phone companies. Those were very much invested in X.25 andd its various spawns. OSI was early on a generalization of X.25. The fact that it came to support datagram service, such as the TP-4 transport and connectionless network layer protocols like ISO 9542 (?) is in large part due to DEC pushing for it to be not quite so much "X.25 on steroids". That also tells us that DEC decided on a "help the Telcos make OSI not be so broken" rather than "ignore the telcos and do it some other way" which would have been hard to pull off outside the USA where it's telcos or nothing. (I remember a DEC Ethernet bridge with a Swedish telco approval sticker. It turned out that at the time in Sweden you could not run your own wiring between floors in your own office building: such cross-floor connectivity was the monopoly of the government telco.)
Last but not least, Phase V was a long running effort. A few bits of it are visible in Phase IV (the weird stuff in the "long data header"). By the time I joined the DNA group in 1984 it was already well underway, but products didn't actually ship for several years afterwards. The landscape in 1983 was rather different from that of 1990.
Data links had some of the same sort of stories. We now know that Ethernet beat everything else, but early on that wasn't so clear. The effort to defeat IBM token ring (802.5) took a long time. I helped write a long DEC document (40-60 pages?), the DEC-3Com reply to IBM Document xyz-nnn, a pile of FUD and baloney about the "superiority" of the IBM token ring.
There was also 802.4, a GM contraption created because of the notion that Ethernet wasn't "real time" enough. 802.4 does have bounded latency that (half duplex) Ethernet doesn't, but the bounds are so high that it doesn't actuallly buy you anything. The only merit of 802.4 is that it is the foundation of FDDI. (No, FDDI has *nothing* to do with 802.5, other than the words "token" and "ring".)
I still remember when we at DEC were busy building FDDI products and one of my colleagues (most likely the manager, Bill Hawe) asked somewhat tongue in cheek "could we just run Ethernet at FDDI speeds?". It didn't take more than a few hours to conclude that the answer is "yes". Even so, when that effort got underway, HP tried to wreck it by a bizarre 100 Mb/s vaguely Ethernet-like protocol. In the end that didn't go anywhere and regular Ethernet took over everywhere.
paul
</pre>
</blockquote>
</body>
</html>