[ih] Why did congestion happen at all? Re: why did CC happen at all?

[Vint Cerf]

Dave, et al,

the ARPANET project was intended to solve the problem of sharing of access
to computing resources and especially research results among the
institutions funded by ARPA to do research in computer science and
artificial intelligence. The method chosen was a radical departure from
conventional circuit switching and you are correct that the first node
installed at UCLA was motivated in part by interest in the mathematical
queueing models that Leonard Kleinrock had used in his dissertation
research at MIT. I was the principal programmer for the Network Measurement
Center. It was clear that ARPA wanted to have the utility of the network to
solve its resource sharing problem but to also take advantage of studying
its behavior. 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.

Thanks to pressure from Larry Roberts and the leadership of Steve Crocker,
the Network Working group developed a collection of applications and
associated protocols such as TELNET, FTP, and networked electronic mail, as
well as demonstrations of multi-computer computation and cooperation (e.g.
distributed air traffic control) that were shown at the ICCC 1972 event in
Washington, DC, that was organized by Bob Kahn at Larry's request.

Very early in the ARPANET development, Larry became aware of the packet
switching work at the UK National Physical Laboratory and from an
interaction in 1967 with Roger Scantlebury, representing Donald Davies'
team at NPL at an ACM Conference. Larry was persuaded to use the highest
speeds available (then 50 kb/s) for the backbone circuits of the network.
The higher the circuit speed, the lower the latency in the network and the
variability of queuing delays. Bob Kahn and I learned about the
CYCLADES/CIGALE network at IRIA in 1973 and visited there where we met
Louis Pouzin, Hubert Zimmermann, Gerard LeLann among others, By 1974,
Gerard spent a year at Stanford contributing to the development of TCP/IP.
Also in 1973, the Ethernet was invented by Bob Metcalfe and David Boggs and
their work on the PARC Universal Packet and related protocols also
influenced the design of TCP/IP.

By July 1975, ARPA concluded that the ARPANET had reached sufficient
stability and it could be handed off to the then Defense Communications
Agency (DCA, now Defense Information Systems Agency) for operation. During
the period 1973-1982, ARPA focused on the design and implementation of the
Internet and at the point where this was activated in January, 1983, the
participating military sites were separated from the academic research
sites and the network split into MILNET and the renewed research ARPANET,
both nets becoming part of the Internet. Other agencies implemented their
own pieces of the Internet. The Department of Energy developed the ESNET
and NASA developed the NSINET while NSF developed the NSFNET. NSF also
facilitated the interconnection of other IP-based research networks in the
US and elsewhere and even the commercial X.25 networks to the growing
Internet. By 1995, NSF concluded that the availability of Internet service
from the commercial sector was sufficient that it could shut down the
NSFNET. ARPA shut down the ARPANET in 1990, in part because the growing
NSFNET had substantially more nodes and capacity than the 50 Kb/s ARPANET
backbone so the research sites of the ARPANET transferred to the so-called
regional NSF network or commercially provided IP networks of the time.

I know you know all this, Dave, so this is just to try to illustrate that
the ARPANET and the many other networks that followed had dual roles as
objects of research and utility. I think the Packet Radio and Packet
Satellite networks that shaped the Internet's design had similar roles and,
in particular, the Packet Satellite network became the sole source of
access to the Internet for the European groups that had been part of the
extended ARPANET. Peter Kirstein's University College London group, in
addition to their pioneering implementation of TCP/IP, also had to make
their Packet Satellite connection work operationally to support a good deal
of traffic between European and US research communities. They switched to
operational use of TCP/IP during 1982, a year before the rest of the
ARPANET community.

Vint





On Sun, Aug 31, 2014 at 7:19 PM, Dave Crocker <dhc2 at dcrocker.net> wrote:

>
> > The ARPANET was never intended as a network for doing research on
> > networks.  It was intended as a production network to facilitate other
> > research.  BBN was very limited in how much experimentation was possible
> > and in what it could try.
>
>
> So they put the first IMP into UCLA, where the Network Measurement
> Center was -- Kleinrock, and all that -- on a whim?
>
> My understanding is that the primary goal was experimentation, but in
> the form of monitoring use and trying different algorithms, rather than
> by conducting artificial traffic exercises.  One might think of this as
> networking as a very different kind of social experiment than we think
> of today...
>
> My other understanding is that the extent of the direct benefit to users
> wasn't quite anticipated, which made it increasingly difficult to make
> changes to the net that could bring it down.  So it was a few years
> before they had to start explicitly scheduling time slots for experiments.
>
> d/
>
> --
> Dave Crocker
> Brandenburg InternetWorking
> bbiw.net
>
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