[ih] Internet-history Digest, Vol 64, Issue 30

[John Shoch]

>> > 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!"