[ih] Arpanet line speed

[Craig Partridge]

Andy's recollection that stuff was 56 Kbps later on matches my recollection
when I came on board in '83.

One thing is I don't remember what the bandwidth was on the satellite links
to England.  My recollection is it was
higher than 9.6Kbps but there was some oddity in integrating European and
US telecom standards such that the bandwidth was different.  But this could
be entirely wrong -- alas the ARPANET maps don't tell me the data rates.

Thanks!

Craig

On Wed, Jan 18, 2017 at 9:59 AM, Andrew G. Malis <agmalis at gmail.com> wrote:

> By the time I came on board in '79, almost all of the links were 56 Kbps,
> with a few 9.6 Kbps links here and there. The 50 Kbps links had been
> replaced by that point.
>
> Cheers,
> Andy
>
>
> On Wed, Jan 18, 2017 at 9:29 AM, Noel Chiappa <jnc at mercury.lcs.mit.edu>
> wrote:
>
>>     > From: Paul Ruizendaal
>>
>>     > - if the modem from the IMP to the Bell System was analog, the best
>>     > technology of the time was perhaps 2.4kb/s ... a speed of 50kb/s is
>> not
>>     > a multiple of 2.4kb/s, and it would have required 21 parallel lines
>>
>> If you read the 303 manual, it's clear that i) the signal between a pair
>> of
>> 303 modems was analog, not digital, and ii) there was a single line, with
>> a
>> wide enough bandpass to carry signals of high enough frequency to carry
>> that
>> bit rate - it didn't glue together a bunch of slower lines.
>>
>>     > if the modem from the IMP to the Bell System was digital, it would
>> most
>>     > likely have used a single channel of a T1 connection
>>
>> The whole T hierarchy was just getting started then (initial deployment
>> in the
>> early 1960s), and I'm not sure if it was deployed widely enough to have
>> made
>> it possible to lease a T1 line from one coast to another.
>>
>> Also, many of these lines would have crossed non-AT+T local phone
>> companies
>> (the Bell System did not control all of the US phone system, although some
>> people don't realize that). The "History of the ARPANET: The First Decade"
>> (which I have previously pointed you at on another list), pg. III-32, says
>> "In the case of a circuit from UCLA to RAND ... the service would be
>> procured
>> from General Telephone" - GT was the largest independent telephone
>> company in
>> the US at that point. It's not clear that those local carriers would have
>> supported T1.
>>
>>
>> Moral of the story: when doing history, it's bad to make assumptions about
>> what was and wasn't possible, and about what did and did not happen. Find
>> contemporary documentation.
>>
>>         Noel
>> _______
>> internet-history mailing list
>> internet-history at postel.org
>> http://mailman.postel.org/mailman/listinfo/internet-history
>> Contact list-owner at postel.org for assistance.
>>
>
>
> _______
> internet-history mailing list
> internet-history at postel.org
> http://mailman.postel.org/mailman/listinfo/internet-history
> Contact list-owner at postel.org for assistance.
>
>


-- 
*****
Craig Partridge's email account for professional society activities and
mailing lists.
For Raytheon business, please email: craig. <craig at bbn.com>
partridge at raytheon.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://elists.isoc.org/pipermail/internet-history/attachments/20170118/d138a0c4/attachment.htm>