[ih] Nit-picking an origin story

[vinton cerf]

the Arpanet might have gotten above 50 kb/s on some links if the original
IMPs were replaced or augmented with BBN's Cxx technology. Steve Crocker
explained the original implementation on analog circuits. Arpanet was
retired in 1990 by which time other packet networks like NSFNET were
running at 45 Mb/s. Subsequent development with optical fiber led to 155
Mb/s, 622 Mb/s, 2.4 Gb/s, 10 Gb/s, 100 Gb/s, 400 and now 800 Gb/s.



On Sun, Aug 24, 2025 at 12:43 PM Barbara Denny via Internet-history <
internet-history at elists.isoc.org> 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://apps.dtic.mil/sti/pdfs/ADA096798.pdf#page=19
>
> 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
>
> http://bärwolff.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
> <http://xn--brwolff-5wa.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>
>
> This was due to the Bell/Western Electric 303C wideband modem using a
> group service of 12 voice circuits.
>
> https://bitsavers.org/communications/westernElectric/modems/303_Wideband_Data_Stations_Technical_Reference_Aug66.pdf#page=6
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