[ih] More topology

[Stephen Casner]

Jack, that map shows one hop from ARPA to USC, but the PDP10s were at
ISI which is 10 miles and 2 or 3 IMPs from USC.

                                                        -- Steve

On Sun, 29 Aug 2021, Jack Haverty via Internet-history wrote:

> Actually July 1981 -- see
> http://mercury.lcs.mit.edu/~jnc/tech/jpg/ARPANet/G81Jul.jpg (thanks, Noel!)
> The experience I recall was being in the ARPANET NOC for some reason and
> noticing the topology on the big map that covered one wall of the NOC.   There
> were 2 ARPANET nodes at that time labelled ISI, but I'm not sure where the
> PDP-10s were attached.   Still just historically curious how the decision was
> made to configure that topology....but we'll probably never know.  /Jack
>
>
> On 8/29/21 8:02 AM, Alex McKenzie via Internet-history wrote:
> >   A look at some ARPAnet maps available on the web shows that in 1982 it was
> > four hops from ARPA to ISI, but by 1985 it was one hop.
> > Alex McKenzie
> >
> >      On Sunday, August 29, 2021, 10:04:05 AM EDT, Alex McKenzie via
> > Internet-history <internet-history at elists.isoc.org> wrote:
> >      This is the second email from Jack mentioning a point-to-point line
> > between the ARPA TIP and the ISI site.  I don't believe that is an accurate
> > statement of the ARPAnet topology.  In January 1975 there were 5 hops
> > between the 2 on the shortest path. In October 1975 there were 6.  I don't
> > believe it was ever one or two hops, but perhaps someone can find a network
> > map that proves me wrong.
> > Alex McKenzie
> >
> >      On Saturday, August 28, 2021, 05:06:54 PM EDT, Jack Haverty via
> > Internet-history <internet-history at elists.isoc.org> wrote:
> >     Sounds right.   My experience was well after that early experimental
> > period.  The ARPANET was much bigger (1980ish) and the topology had
> > evolved over the years.  There was a direct 56K line (IIRC between
> > ARPA-TIP and ISI) at that time.  Lots of other circuits too, but in
> > normal conditions ARPA<->ISI traffic flowed directly over that long-haul
> > circuit.   /Jack
> >
> > On 8/28/21 1:55 PM, Vint Cerf wrote:
> > > Jack, the 4 node configuration had two paths between UCLA and SRI and
> > > a two hop path to University of Utah.
> > > We did a variety of tests to force alternate routing (by congesting
> > > the first path).
> > > I used traffic generators in the IMPs and in the UCLA Sigma-7 to get
> > > this effect. Of course, we also crashed the Arpanet with these early
> > > experiments.
> > >
> > > v
> > >
> > >
> > > On Sat, Aug 28, 2021 at 4:15 PM Jack Haverty <jack at 3kitty.org
> > > <mailto:jack at 3kitty.org>> wrote:
> > >
> > >      Thanks, Steve.  I hadn't heard the details of why ISI was
> > >      selected.   I can believe that economics was probably a factor but
> > >      the people and organizational issues could have been the dominant
> > >      factors.
> > >
> > >      IMHO, the "internet community" seems to often ignore non-technical
> > >      influences on historical events, preferring to view everything in
> > >      terms of RFCs, protocols, and such.  I think the other influences
> > >      are an important part of the story - hence my "economic lens".
> > >      You just described a view through a manager's lens.
> > >
> > >      /Jack
> > >
> > >      PS - I always thought that the "ARPANET demo" aspect of that
> > >      ARPANET timeframe was suspect, especially after I noticed that the
> > >      ARPANET had been configured with a leased circuit directly between
> > >      the nearby IMPs to ISI and ARPA.   So as a demo of "packet
> > >      switching", there wasn't much actual switching involved.   The 2
> > >      IMPs were more like multiplexors.
> > >
> > >      I never heard whether that configuration was mandated by ARPA, or
> > >      BBN decided to put a line in as a way to keep the customer happy,
> > >      or if it just happened naturally as a result of the ongoing
> > >      measurement of traffic flows and reconfiguration of the topology
> > >      to adapt as needed.  Or something else.   The interactivity of the
> > >      service between a terminal at ARPA and a PDP-10 at ISI was
> > >      noticeably better than other users (e.g., me) experienced.
> > >
> > >      On 8/28/21 11:51 AM, Steve Crocker wrote:
> > > >      Jack,
> > > >
> > > >      You wrote:
> > > >
> > > >          I recall many visits to ARPA on Wilson Blvd in Arlington, VA.
> > > >          There were
> > > >          terminals all over the building, pretty much all connected
> > > >          through the
> > > >          ARPANET to a PDP-10 3000 miles away at USC in Marine Del Rey,
> > > >          CA.  The
> > > >          technology of Packet Switching made it possible to keep a
> > > >          PDP-10 busy
> > > >          servicing all those Users and minimize the costs of everything,
> > > >          including those expensive communications circuits.  This was
> > > >          circa
> > > >          1980. Users could efficiently share expensive communications,
> > > > and
> > > >          expensive and distant computers -- although I always thought
> > > >          ARPA's
> > > >          choice to use a computer 3000 miles away was probably more to
> > > >          demonstrate the viability of the ARPANET than because it was
> > > >          cheaper
> > > >          than using a computer somewhere near DC.
> > > >
> > > >
> > > >      The choice of USC-ISI in Marina del Rey was due to other
> > > >      factors.  In 1972, with ARPA/IPTO (Larry Roberts) strong support,
> > > >      Keith Uncapher moved his research group out of RAND.  Uncapher
> > > >      explored a couple of possibilities and found a comfortable
> > > >      institutional home with the University of Southern California
> > > >      (USC) with the proviso the institute would be off campus.
> > > >      Uncapher was solidly supportive of both ARPA/IPTO and of the
> > > >      Arpanet project.  As the Arpanet grew, Roberts needed a place to
> > > >      have multiple PDP-10s providing service on the Arpanet.  Not just
> > > >      for the staff at ARPA but for many others as well.  Uncapher was
> > > >      cooperative and the rest followed easily.
> > > >
> > > >      The fact that it demonstrated the viability of packet-switching
> > > >      over that distance was perhaps a bonus, but the same would have
> > > >      been true almost anywhere in the continental U.S. at that time.
> > > >      The more important factor was the quality of the relationship.
> > > >      One could imagine setting up a small farm of machines at various
> > > >      other universities, non-profits, or selected for profit companies
> > > >      or even some military bases.  For each of these, cost,
> > > >      contracting rules, the ambitions of the principal investigator,
> > > >      and staff skill sets would have been the dominant concerns.
> > > >
> > > >      Steve
> > > >
> > >
> > >
> > > --
> > > Please send any postal/overnight deliveries to:
> > > Vint Cerf
> > > 1435 Woodhurst Blvd
> > > McLean, VA 22102
> > > 703-448-0965
> > >
> > > until further notice