[ih] More topology

[Jack Haverty]

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
>>
>>
>>