[ih] Significant milestones in the history of TCP/IP

[John Day]

The line speed was very important.  Remember the ARPANET was built to be a production network to lower the cost of ARPA research on other things. It was to have major sites dedicated to compute and others to storage.  The Net would have worked, but in terms of Robert’s goal of a resource sharing network that would allow sharing of major computing resources, it would have been painfully slow, and probably deemed a failure.  The 56K lines kept the perceived response within expectations. All of the people not doing networking but using the ARPANET for other projects, of which there were a lot, would have found it more a barrier.  There were a lot of people submitting “big jobs” to CCN, Rutherford, Multics, etc. Tenex’ character-at-a-time echoing would have been even worse than it was. (It was easy to type a line and a half ahead in those days before starting to get echoed characters.)  Having the 56K lines at the beginning (which were hard to saturate for any sustained period) was a real boon that allowed us to treat it like a resource sharing facility, which is what generated the excitement.

Even those days, 9.6K was reasonable speed for one person (maybe two) at a terminal doing development.  Sharing that with a few hundred with more than a few doing essentially file transfers for RJE and you have one painfully slow network.  And even then the greater popularity for some sites was prevalent. 

Starting with high speed lines meant that a whole raft uglinesses were avoided.

> On Sep 16, 2015, at 10:32, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
> 
>> From: Vint Cerf <vint at google.com>
> 
>> actually their experience with a one-node local area network influenced
>> Roberts' choice of data rate. Roger Scantlebury attended the 1967
>> meeting at which he met Larry and said that higher speed would reduce
>> delay. Larry ended up with 50 Kb/s lines rather slower 2.4 kb/s lines.
> 
> Ah, right, now that you mention it, I do recall that. I wonder how important
> a technical point that was, though? (See discussion below.)
> 
> I should emphasize that I'm mostly focused on technical influences, in asking
> this. I know he and his co-workers had a big influence, in terms of 'moral
> suppport', etc, but that's different. I should further emphasize that I have
> _no_ axe _at all_ to grind, here - I simply want to know the truth. If he
> deserves a ton of credit, fine; if his _technical_ influence was modest, fine
> too. (And as a UK citizen living in the US, I claim to be pretty free of
> national bias! :-)
> 
> 
>> From: Alex McKenzie <amckenzie3 at yahoo.com>
> 
>> Davies team told Larry Roberts about Paul Baran's work, which Larry was
>> unaware of.
> 
> I think a better way to put it would be that they got Larry to go back and
> look at Baran's work, because the documentary record shows _definitively_
> that he had contact with Baran's work _before_ he met Roger Scantlebury at
> the October, 1967 meeting in Gatlinburg.
> 
> If you look at Baran's Oral History from the CBM (OH-182), pg. 37, you will
> find that Baran found documentary records (his old calendar) showing a visit
> from Larry Roberts in February, 1967 (the 28th, to be exact) - well before
> the Gatlinburg meeting.
> 
> The interesting question, of course, is why Larry _apparently_ didn't pay
> much attention to Baran's work until the NPL people mentioned it? This is
> probably related to a question I've asked here before - why Baran's paper in
> the '64 IEEE ToN journal didn't get more attention. Maybe Larry got too
> focused on the _goals_ of Baran's work, and thus felt it wasn't relevant to
> his project?
> 
> 
>> At a later time Davies team (Roger Scantlebury) also convinced Larry to
>> build the ARPAnet with a small number of "high speed" (50kbps) lines
>> rather than a large number of "low speed" (9.6 & 19.2 kbps) lines.
> 
> I'm trying to work out how important that was, technically. Would an ARPANET
> built, as you put it, of more, slower lines have worked? I.e. how critical
> was that intervention? We can only guess as to how the history would have
> unfolded without it, although one can do some analysis.
> 
> The routing in a network with more, slower, links would have become an issue
> sooner than it did - becaue of both the size of the routing table, and also
> the slower update rate on the slower lines. However, but it's unclear how
> much of a problem that would have been - lagging response to changes was,
> after all, eventually solved by McQuillan. Would the network have behaved so
> poorly that it didn't last long enough for McQuillan to show up?
> 
> I'm not sure about congestion, etc (e.g. re-assembly) issues - would those
> have been enough worse in an ARPANET with many more, but slower, links?
> 
> And of course the big un-knowable is 'had the network been attempted to be
> built with many, slow, links, and had it not worked, would the people
> building it have recognized the need to move to faster links, and if so, how
> soon'?
> 
> I ask these questions (even though they have no immediately clear answers -
> or for the last, probably cannot be answered) because the answers to them are
> needed before one can really assess how important a technical intervention
> this was.
> 
> 
>> Whether anything about the ARPAnet had much to do with the history of
>> TCP/IP is a different question, but if people think the answer to that
>> question is "yes"
> 
> I'd say very much 'yes': it showed that packet switching could work, taught
> us a first round of technical lessons in that area, and many of the
> applications were staples of the early Internet.
> 
> Of course, in an alternate history, maybe NPL's work would have done the same
> if the ARPANET never existed, so who knows? Perhaps the CYCLADES work was even
> more important, because I don't know of an alternative that might have taught
> us the lessons it did about moving reliability into the hosts.
> 
>       Noel
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