[ih] Question re rate of growth of the Arpanet

[Steve Crocker]

Geoff,

To add a bit more, I believe Larry Roberts was originally thinking in terms
of 9600 baud lines.  However, he discovered the U.S. Government had access
to a special Bell tariff for these 50 kb/s circuits.  As Vint said, the 50
kb/s was implemented using twelve voice grade circuits and a Western
Electric series 303A modem.  Bottom line, Larry found this item in the
government catalog that provided this bandwidth and was within his budget.

Steve


On Mon, Apr 21, 2025 at 2:11 PM Vint Cerf <vint at google.com> wrote:

> Best you could do with 12 3KHz bonded channels on a Bell 303 modem
>
> V
>
> Please send any postal/overnight deliveries to:
> Vint Cerf
> Google, LLC
> 1900 Reston Metro Plaza, 16th Floor
> Reston, VA 20190
> +1 (571) 213 1346
>
>
> until further notice
>
>
>
>
> On Mon, Apr 21, 2025, 14:09 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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>> >
>> >
>>
>> --
>> Geoff.Goodfellow at iconia.com
>> living as The Truth is True
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