[ih] Nit-picking an origin story

[Guy Almes]

Barbara et al.,
   There are (at least) two issues.
<> When the original ARPAnet IMPs were deployed, the availability of 
those special 50 Kb/s circuits, complete with 303A modem etc., were the 
key enabling technology.  As many have pointed out, something like the 
ARPAnet could have been built with lower-speed circuits, but it would 
have been much less successful both as infrastructure and as 
demonstration of how the future could unfold.

<> When the last additions to the ARPAnet were deployed during the 
1980s, I suspect that digital 56 kb/s circuits were used.  Once the Bell 
system started to deploy those digital circuits, they were 
surely/probably both cheaper and more reliable.  Can someone verify (or 
falsify) that?
	-- Guy

On 8/24/25 12:43 PM, Barbara Denny via Internet-history wrote:
> 
>   You might hear 56 kb/sec from other people.  I was surprised to hear 50 kb/sec from this list somewhat recently.  Of course my memory could be wrong but i always thought it was 56 kb/sec.  Did anything change by the mid 80s? Your quotation says normally 50 kb/sec from the ARPAnet brochure in 1980.
> barbara
>      On Sunday, August 24, 2025 at 05:25:04 AM PDT, Lars Brinkhoff via Internet-history <internet-history at elists.isoc.org> wrote:
>   
>   Jack Haverty wrote:
>> Performance was also an issue as the ARPANET grew and traffic
>> increased.  One of the limiting factors to performance was the routing
>> algorithm.   Packets were always sent on the "shortest" path.   But
>> that meant that the aggregate performance was also limited to
>> 56kb/sec, which was the maximum line speed of any path.
> 
> I beleve the correct number is 50,000 bits/second.
> 
> ARPANET Information Brochure, from 1980.
> "The complete network is formed by interconnecting the nodes through
> wideband communication lines, normally 50,000 bits per second (50KBPS),
> supplied by common carriers."
> https://urldefense.com/v3/__https://apps.dtic.mil/sti/pdfs/ 
> ADA096798.pdf*page=19__;Iw!!KwNVnqRv! 
> D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE- 
> yM8vZnOWRpX72kK_NSeQtg$ <https://urldefense.com/v3/__https://apps.dtic.mil/sti/pdfs/ADA096798.pdf*page=19__;Iw!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kK_NSeQtg$>
> 
> BBN Report 1928, from 1970.
> "In the last quarter, we designed and implemented a test program to
> obtain data on the performance of the fifty kilobit communication
> circuits" kb/sec
> https://urldefense.com/v3/__http://b**Arwolff.de/bbn-arpanet-reports- 
> collection/ 
> BBN*20(1970)*20Interface*20Message*20Processors*20for*20the*20ARPA*20Computer*20Network*20(Report*201928,*20Quarterly*20Technical*20Report*204).pdf*page=10__;w6QlJSUlJSUlJSUlJSUlJSUj!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kJ9un2NJg$ <https://urldefense.com/v3/__http://b**Arwolff.de/bbn-arpanet-reports-collection/BBN*20(1970)*20Interface*20Message*20Processors*20for*20the*20ARPA*20Computer*20Network*20(Report*201928,*20Quarterly*20Technical*20Report*204).pdf*page=10__;w6QlJSUlJSUlJSUlJSUlJSUj!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kJ9un2NJg$>
> 
> This was due to the Bell/Western Electric 303C wideband modem using a
> group service of 12 voice circuits.
> https://urldefense.com/v3/__https://bitsavers.org/communications/ 
> westernElectric/ 
> modems/303_Wideband_Data_Stations_Technical_Reference_Aug66.pdf*page=6__;Iw!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kKcZ8ttpw$ <https://urldefense.com/v3/__https://bitsavers.org/communications/westernElectric/modems/303_Wideband_Data_Stations_Technical_Reference_Aug66.pdf*page=6__;Iw!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kKcZ8ttpw$>
> -- 
> Internet-history mailing list
> Internet-history at elists.isoc.org
> https://urldefense.com/v3/__https://elists.isoc.org/mailman/listinfo/ 
> internet-history__;!!KwNVnqRv! 
> D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE- 
> yM8vZnOWRpX72kK8m_HKNA$ <https://urldefense.com/v3/__https://elists.isoc.org/mailman/listinfo/internet-history__;!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kK8m_HKNA$>
> -
> Unsubscribe:https://urldefense.com/v3/__https://app.smartsheet.com/b/ 
> form/9b6ef0621638436ab0a9b23cb0668b0b? 
> The*20list*20to*20be*20unsubscribed*20from=Internet-history__;JSUlJSU!! 
> KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6- 
> RwfYOUiaooE-yM8vZnOWRpX72kJdI4nC0A$ <https://urldefense.com/v3/__https://app.smartsheet.com/b/form/9b6ef0621638436ab0a9b23cb0668b0b?The*20list*20to*20be*20unsubscribed*20from=Internet-history__;JSUlJSU!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kJdI4nC0A$>
>    
> -- 
> Internet-history mailing list
> Internet-history at elists.isoc.org
> https://urldefense.com/v3/__https://elists.isoc.org/mailman/listinfo/ 
> internet-history__;!!KwNVnqRv! 
> D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE- 
> yM8vZnOWRpX72kK8m_HKNA$ <https://urldefense.com/v3/__https://elists.isoc.org/mailman/listinfo/internet-history__;!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kK8m_HKNA$>
> -
> Unsubscribe:https://urldefense.com/v3/__https://app.smartsheet.com/b/ 
> form/9b6ef0621638436ab0a9b23cb0668b0b? 
> The*20list*20to*20be*20unsubscribed*20from=Internet-history__;JSUlJSU!! 
> KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6- 
> RwfYOUiaooE-yM8vZnOWRpX72kJdI4nC0A$ <https://urldefense.com/v3/__https://app.smartsheet.com/b/form/9b6ef0621638436ab0a9b23cb0668b0b?The*20list*20to*20be*20unsubscribed*20from=Internet-history__;JSUlJSU!!KwNVnqRv!D2hHWHot7vQUTsuR1iUtBsCPl1_OXbFE00gO-0aiv8dlpDRPu_x1_qu3HN6-RwfYOUiaooE-yM8vZnOWRpX72kJdI4nC0A$>
>