[ih] Internet-history Digest, Vol 64, Issue 31

[Lawrence Stewart]

I’ll add a little bit more to John Shoch’s story about the PARC involvement in PRNet.

Credit to Dave Boggs for teaching me the correct way to design Alto hardware, which explains why the Alto-1822 is as small as it is.  There’s a photo in ien78.

Credit to Hal Murray, whose Mesa Gateway software was used for the PRNet work, rather than the BCPL version.

There’s a technical report, see https://www.rfc-editor.org/ien/ien78.pdf

>   2. Re: Internet-history Digest, Vol 64, Issue 30 (John Shoch)
> Message: 2
> Date: Wed, 26 Mar 2025 22:24:27 -0600
> From: John Shoch <j at shoch.com>
> To: internet-history at elists.isoc.org
> Subject: Re: [ih] Internet-history Digest, Vol 64, Issue 30
> Message-ID:
> 	<CAFrK2diHEMRGPrKoO0OBzd+QhGn3aj__mU5MBwxojY7WmPVZFw at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
> 
>>>> On Mar 26, 2025, at 16:57, Vint Cerf via Internet-history <
> internet-history at elists.isoc.org <mailto:internet-history at elists.isoc.org>>
> wrote:
> 
>>>> I think we had a fair number of nodes - at least a half dozen, possibly
>>>> more? Don would know, if you don't Barbara.
>>>> Yes to multiple mountain sites. Eichler - sounds like somebody's
> house! I
>>>> used to live in an Eichler in Palo Alto but never had a packet radio
>>>> installed. Xerox PARC had one (fixed location) though.
> 
> Vint is understating his generosity and support:
> 
> --Vint (at Arpa) and Don Nielson and team (at SRI) supported us with TWO
> Packet Radio Units in Palo Alto.
> --They were stationary installations, at the main PARC building and another
> about a mile away.
> --The PRUs had an 1822 interface, and we had built an 1822 interface for
> the Alto (to connect to an Imp).
> --So we built 2 more interfaces, and had an Alto at each PRU -- which ran
> our standard internet gateway, and could also connect to an Ethernet, and
> then on to the rest of our internet.
> --We did not modify the PRU code.  A network driver was written to
> encapsulate internet packets for transmission through the PRNet, so it
> became a transit network between two Ethernets (and packets coming off the
> PRNet could be routed on through other gateways to machines elsewhere in
> the country).
> --The PRNet and an Ethernet differed in throughput by maybe 2 decimal
> orders of magnitude -- so it taught us all a lot about flow and congestion
> control, retransmission algorithms, lossy sub-neworks, delayed duplicates,
> intra-network fragmentation, and more..
> --It was a great experiment.
> 
> Could not have done it without Vint, Don, et al.
> (I helped organize the project, but real kudos go to Larry Stewart, who
> made it all happen!)
> 
> John
> 
> PS:  I sometimes give a talk that includes a picture of a rack of equipment
> holding the PRU and the Alto gateway -- and then quip, "If you squint real
> hard, and apply pressure from 20-30 years of Moore's law, out pops a WiFi
> access point!"
> 
>