[ih] Question re rate of growth of the Arpanet

[Steve Crocker]

I may be wrong about 9.6.  It's what I recall when this was relayed to me,
but I'd want to track down a more authoritative source.

Re U.S. distances: In 1968 I was in Boston until May and then in Los
Angeles.  The University of Utah was just barely beginning to come to
people's attention in the computer science community.  When I mentioned the
university to people in Boston, someone said it was near Los Angeles.  When
I mentioned it to a friend in Los Angeles, she thought it was near Chicago
:)

Steve


On Mon, Apr 21, 2025 at 2:33 PM John Day <jeanjour at comcast.net> wrote:

> theRoberts had originally planned to use 2.4Kbps lines. Roger Scantlebury
> (and others) at the Gatlinburg Operating System Conference in the Fall of
> 67 (it appears to have been one of *those* bar discussions) ;-) convinced
> him that given NPL’s experience with their packet-switched network they had
> found that that was way too slow and he should use 50Kbps.
>
> Both Baran and Davies independently had come to the conclusion that
> 1.5Mbps would be best but it wasn’t available yet.
>
> There are two things I find amusing about this:
> 1) The ARPANET would have worked at 2.4 or 9.6, etc. But would have been
> deemed so slow to prove that the effort wasn’t really successful. At 50K,
> we could really get work done. Not many systems could sustain that and
> there weren’t many applications needing all of that. Using 50K was a much
> larger part of the ARPANET’s success than we often give it credit for.
>
> 2) Roger’s experience was for the NPL campus network. I am not sure Roger
> had any idea what 50K (which were expensive!) would do to Roberts budget
> for a nation-wide network in the US.  ;-) At the time, most Europeans and
> many East Coast Americans had no sense of distances in the US. (I remember
> a tale of 3 IBMers sent from Poughkeepsie to Detroit to work on some
> customer's system, who thought as long as they were that far West, they
> could drive to Las Vegas for the weekend.) (!!) ;-) (31 hours now with
> Interstates which were not complete then.)  Good thing ARPA’s pockets were
> deep. ;-)
>
> O, and at that conference, Roger convinced Roberts to use packet
> switching, which he had not heard of. (He did find Baran’s papers in a
> stack he hadn’t read when he got back to DC.)
>
> Both are great serendipity, that had a profound effect and for the most
> part lost in history. I always find these kinds of things delightful.
>
> Take care,
> John
>
> > On Apr 21, 2025, at 14:08, the keyboard of geoff goodfellow via
> Internet-history <internet-history at elists.isoc.org> wrote:
> >
> > steve, can you elucidate any history with respect to how/why the speed of
> > 50 kb/s was chosen for the ARPANET lines?  were there great speeds
> > available then?
> >
> > yours truly kinda (perhaps mistakenly) recalls these 50 kb/s "wideband
> > circuits of the day" were primarily used for linking tv broadcast
> affiliate
> > stations to/with their motherships (cbs, nbc, abc, ...)?
> >
> > geoff
> >
> > On Mon, Apr 21, 2025 at 7:26 AM Steve Crocker via Internet-history <
> > internet-history at elists.isoc.org> wrote:
> >
> >> Thanks for the pointer to RFC 597.
> >>
> >> As I looked at it, an aspect I hadn't considered before came to mind.
> >>
> >> Installation of an IMP required provisioning 50 kb/s lines to two or
> three
> >> other points.  In the early days, we installed roughly a new IMP once a
> >> month.  (The lead time for ordering 50 kb/s lines from AT&T was NINE
> >> months.)
> >>
> >> Once an IMP was installed, new hosts could be added to the IMP as
> quickly
> >> as the site could build or obtain the host-IMP interface and write or
> >> obtain the software for their operating system.
> >>
> >> If anyone has the dates for each of the hosts, it would be interesting
> to
> >> compare the growth of IMPs vs growth of hosts.
> >>
> >> Steve
> >> --
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> >> https://elists.isoc.org/mailman/listinfo/internet-history
> >>
> >>
> >
> > --
> > Geoff.Goodfellow at iconia.com
> > living as The Truth is True
> > --
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> > https://elists.isoc.org/mailman/listinfo/internet-history
>
>

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