[ih] ARPANET, operational/experimental

[John Day]

I agree with you, Dave.  It *was* a success.  And as I said earlier, 
we use to joke that it was almost too successful!  We might have done 
more experimenting if you guys had gotten more wrong.  ;-)

To a very large extent, the whole ARPANET was an experiment on 
whether or not the whole idea was at all feasible.  You had to build 
*one* to have a better idea of what else to look at and to know what 
was and wasn't important.

To some extent, this is an example of my view that the thing about CS 
is that "we build what we measure."  So we often have to build one to 
know what it is we need to build.  ;-)  In this case, the first one 
was pretty damn good!  ;-)



At 7:24 AM -0400 9/1/14, Dave Walden wrote:
>At 08:56 PM 8/31/2014, Vint Cerf wrote:
>
>>The first time I met Bob Kahn and Dave Walden was on the occasion 
>>of their visit to UCLA in late 1969 or early 1970 to conduct a 
>>series of experiments to generate traffic and observe the way in 
>>which the IMPs and their protocols and algorithms responded. Bob 
>>Kahn had concerns that under certain conditions the network would 
>>lock up and this visit was a first opportunity to use the then 
>>4-node network to stress its capacity.  In the course of a couple 
>>of weeks, Bob designed and I programmed a series of traffic 
>>generation and network measurement experiments that indeed locked 
>>the network up multiple times and in multiple ways. Reassembly 
>>lockup and store-and-forward lockup stand out in my mind in 
>>particular.
>>
>
>Dave W.:
>
>>In my mind the years of the ARPANET were a big experiment in 
>>whether IMP hardware and sofware and host software and hardware and 
>>IMP/host interfaces and host/host protocols and NWG collaboration 
>>could be developed and made to work reliably enough such that the 
>>hosts could talk to each other, experiments could be run (e.g., at 
>>the NMC, trying packet voice, trying internetworkimg, trying 
>>improved routimg, ...), and various users could try ("experiment") 
>>using the net to do their more or less operational work (e.g., 
>>using a TIP to access a mainframe computer rather than havin one's 
>>own, using the net rather than specially leased lines to move 
>>seismic data from Norway to Alexandria, ...).  And certainly some 
>>of our "operational" improvements seemed like experiments ("now 
>>that we have check summed the routing packets, I wonder if we will 
>>see more of those routing kind of crashes").
>>
>
>In the case of the lock-ups mentioned by Vint, my memory is that Bob 
>and I could make them happen just using the IMPs' internal traffic 
>generators, and then Vint and Bob did a more systematic series of 
>tests. And then much study, a simulation, and a report done back at 
>BBN eventually led to the IMP code changes that were implemented. 
>See
> 
>http://xn--brwolff-5wa.de/bbn-arpanet-reports-collection/BBN%20(1971)%20A%20Study%20of%20the%20Arpa%20Network%20Design%20and%20Performance%20(Report%202161).pdf
>In the meantime while the change was being developed, we asked the 
>hosts to please try to avoid generating traffic of the kind now 
>known to lock up the net, and they did avoid it and the net 
>continued to be used "operationally" for its other work and 
>experiments.
>
>We all had our roles in this big experiment.  A significant part of 
>the BBN "IMP guys" role was to "keep it running" while continuing to 
>improve it and making changes to facilitate the experiments other 
>groups were doing.  I think the experiment of building the ARPANET 
>and improving it for a number of years was a success.
>
>Dave (W.)