[ih] Recently restored and a small ARPANET was run using simulated IMP hardware. (was: TTL [was Exterior Gateway Protocol])

Craig Partridge craig at tereschau.net
Mon Sep 7 15:30:15 PDT 2020


Two quick followups to Jack's note.

Dave Mills wrote a retrospective on the Fuzzball in 1988 in SIGCOMM '88. (
https://www.eecis.udel.edu/~mills/database/papers/fuzz.pdf).

When I knew the Packet Radio work, it was supervised by Jil Westcott (Div
4) and there was a rack of PRs in a computer room in 10 Moulton right by
the bridge.  Data rates, even over a few feet, were painfully slow and the
late Charlie Lynn was the lead programmer.  I have a vague recollection
(perhaps wrong) of Charlie commenting that the links were so bad, that
getting even minimal information between the devices was a challenge.

Craig



On Mon, Sep 7, 2020 at 12:00 PM Jack Haverty via Internet-history <
internet-history at elists.isoc.org> wrote:

> Hi Barbara,
>
> Packet Radio artifacts of any kind were elusive (at least in 2013 when
> we searched), except for a few conference papers.  Specifically, we were
> looking for things like QTRs or other project reports that SRI
> presumably submitted to ARPA, analogous to the BBN QTRs.   We found a
> lot of the BBN reports online at DTIC, but little from SRI.  I'm not
> sure, but the BBN QTRs may have been found by the search engine because
> I had the BBN/ARPA contract numbers involved, but I didn't know the
> appropriate contract numbers for the SRI (or any other) contracts.
>
> Not much detail about Fuzzballs, or Port Expanders, or other such boxes
> that were prolific in the early days of the Internet.  Google wasn't
> much help, but that may be from lack of knowledge in how to best use the
> search mechanisms.
>
> IMHO, there wasn't as much collaboration between the ARPANET and Packet
> Radio as there was with the Internet/Gateway work at BBN.
>
> BBN had internal structure that to some extent influenced the
> "technology transfer" between projects.  In particular there were two
> "divisions", Div4 and Div6, that both did similar computer and network
> research.  Div6 was where the ARPANET project began and evolved to an
> operational service over the ten years preceding the Internet, so there
> was a lot of operational experience and war wounds there.   Div4 was
> where the Packet Radio work was done, along with lots of other things,
> such as TENEX.   Both were very competent, but had different experiences.
>
> Although the technical staffs of the two divisions got along pretty
> well, pragmatic details limited collaboration.  We were physically
> located in separate buildings, so hallway encounters and casual
> interactions were less likely.  Interesting "teaching events" that
> occurred in the ARPANET propagated quickly through Div6 where the NOC
> was literally just down the hallway, less so to Div4.   Cross-charging
> (charging your time to the other Division's project) was possible but
> discouraged.
>
> The "Gateway Project" began in Div4, where Ginny Strazisar implemented
> the first gateway;  I don't know if that was a separate
> project/contract, or just a part of the Packet Radio contract at the
> time.   Some few years later, as it became desirable for the Internet to
> stabilize and become an operational service, ARPA moved the gateway work
> from Div4 to Div6, folding it into the "Internet Project" contract that
> was my responsibility at the time (it included various TCP
> implementations, SATNET, WBNET, Remote Site Maintenance, etc.).
>
> That was the point where we started injecting "ARPANET DNA" into the
> Internet/gateways, blatantly adopting ARPANET techniques as the most
> obvious (to us in Div6) way to get the Internet to be as managed as the
> ARPANET.
>
> I know little about the internal mechanisms of the Packet Radio
> environment.   But it did not move to Div6 (which became BBN
> Communications Corp at some point) at least during my involvement
> (roughly 1978-1990).
>
> So I suspect that the Packet Radio system did not reuse much of the IMP
> ideas/techniques, especially the ones that were rather mundane and not
> well documented or publicized (such as the "reload from neighbor"
> idea).  The Packet Radio QTRs, if they survive, would probably answer
> that question.
>
> I've often wondered, from a historical perspective now, to what extent
> things like internal corporate structure and organizational decisions
> influenced the design and implementation of the Internet.
>
> /Jack
>
>
> On 9/6/20 11:44 PM, Barbara Denny via Internet-history wrote:
> >  Because of BBN's involvement, I am thinking Packet Radio might have
> reused many of  the same ideas as the IMPs for loading new software from
> another node. Do you know this was not the case?  I never needed to look at
> that part of the code.
> > I remember using XNET for examination of the Packet Radio station. Given
> your recent email it sounds like you looked for old Packet Radio station
> software and couldn't find it. Is this correct?
> > I don't think Rockwell released their Packet Radio software in the late
> 70s/early 80s. I would have to contact Rockwell if I thought bugs required
> a change to a packet radio, versus the Packet Radio station, when I worked
> at BBN. I know several years later SRI did get some of their code  because
> I implemented one of the new routing algorithms ( I am pretty sure it was
> called threshold distance vector routing if anyone is interested). BTW, I
> think the software may have only been tested in a simulator due to delays
> in the delivery of the LPR (Low Cost Packet Radio). This was during the
> SURAN program.
> > The first demo of Packet Radio and ARPANET in 1976 involved submitting
> the status report.  Don Nielson would probably remember if that was done
> through anything like email. Below is a link to an article that discusses
> this event. The text from the article mentions email but more importantly
> it has a link to a podcast with Don. I didn't know this podcast existed so
> I still need to listen to it.  I can see why you might think the report
> submission may have been done by using a telnet connection to a SRI host
> that had email.
> >
> https://hightechforum.org/happy-birthday-internet-richard-bennett-talks-with-don-nielson/
> > barbara
> >     On Sunday, September 6, 2020, 12:39:38 PM PDT, Jack Haverty via
> Internet-history <internet-history at elists.isoc.org> wrote:
> >
> >  Hi Geoff - thanks for that bit of history and kudos!
> >
> > I think there's an Internet connection in your experience.  I'm not sure
> > what, legally, "wireless email" means.  But I suspect that email was
> > being sent and received, wirelessly, well before even 1982, if only to
> > and from the SRI Packet Radio van that could occasionally be seen then
> > roaming around the Bay Area.
> >
> > Of course, technically, that probably involved a Telnet connection,
> > wirelessly, to some PDP-10 running an email program.   But, legally, it
> > might meet the court accepted definition of "wireless email".   I
> > learned from the lawyers that much of litigation involves arguing about
> > the meaning of words and phrases.
> >
> > So, perhaps someone could have looked for mouldering Packet Radio (aka
> > PR) hardware and software, and demonstrated wireless email circa 1978
> > over one or more PRNETs.
> >
> > Sadly, although I was pretty sure that interesting "prior art" would be
> > found in the PR environment, we had little success 7 years ago while
> > trying to find anything that might show exactly how PR equipment
> > "downloaded instructions".
> >
> > There's remarkably little readily discoverable material about lots of
> > the computer and network systems of the 70s/80s, especially internal
> > details of operation, tools, procedures, etc.   Plenty of stuff on
> > Routing, but little on other mechanisms, or other types of networks of
> > that era, at least that the lawyers and I could find.   IMHO, that's a
> > huge gap even in Internet History, since the Internet did not evolve in
> > a vacuum, was itself composed of more than the ARPANET, and was
> > surrounded by competitors (remember multiprotocol routers).
> >
> > /Jack
> >
> > On 9/6/20 11:58 AM, the keyboard of geoff goodfellow wrote:
> >> Jack, you're a Most Eloquent purveyor of history and that WHY explain
> >> is exactly what yours truly was hoping for... Thank You for the
> >> elucidation! :D
> >>
> >> along the lines vis-a-vis:
> >>
> >>     So, that's a bit about the "Why", for history to ponder.  The
> >>     experience got me wondering about the "patent history" of The
> >>     Internet.  Clearly there was a lot of innovation in those days.
> >>     My recollection is that very little was patented, even if only to
> >>     make sure no one else could.  Maybe someone will document the
> >>     patent-related aspects of Internet History someday.
> >>
> >> please excuse/pardon this immodesty: yours truly had a kinda similar
> >> "lawyered" experience with respect to WHO was the purported
> >> "inventor"/originator of wireless email in a patent litigation case
> >> and the "challenge" of finding/presenting any extant legally
> >> submissive "artifactual proof" to that effect -- for which John
> >> Markoff at the New York Times wrote about in this 2006 article:
> >>
> >> In Silicon Valley, a Man Without a Patent
> >>
> https://www.nytimes.com/2006/04/16/business/technology/in-silicon-valley-a-man-without-a-patent.html
> >>
> >> for which some links of "proof" exist -- for some stuff mentioned in
> >> the above NYT article -- on my website https://iconia.com/ under
> >> "wireless email" (in case any historians are duly interested)...
> >>
> >> geoff
> >>
> >> On Sun, Sep 6, 2020 at 8:24 AM Jack Haverty <jack at 3kitty.org
> >> <mailto:jack at 3kitty.org>> wrote:
> >>
> >>     Geoff,
> >>
> >>     Dave's IEEE paper does an excellent job of the
> >>     Who/What/When/Where.  He's right that it was about 7 years ago.
> >>     Time flies... but I guess it's still "recent" when viewed as part
> >>     of Internet History.
> >>
> >>     For the curious, I can add a bit more about the Why.
> >>
> >>     Sometime in 2013, I got an email out of the blue from Charlie
> >>     Neuhauser, someone I didn't recognize or remember at all, asking
> >>     if I was the "Jack Haverty" who authored IEN 158 - documenting the
> >>     XNET protocol in 1980.   Figuring that the statute of limitations
> >>     must have expired after 30+ years, I cautiously said yes.  Over
> >>     the next few days, he hooked me up with the lawyers who were
> >>     involved in a patent dispute - one that had been going on for
> >>     several decades by then.  In fact, the patent involved had been
> >>     issued, ran its 17 year lifetime, and expired, but there was still
> >>     litigation in process about whether or not the patent was valid,
> >>     and 17 years of violations were alleged cause for compensation in
> >>     the many millions.   For the next few years I was involved in the
> >>     battles, working with the lawyers scattered all over the country.
> >>     I never met any of them.  All our work was done by email and
> >>     telephone.   No Zoom then or we probably would have used it.
> >>
> >>     The core issue in the patent battle concerned "downloading
> >>     instructions", mechanisms such as would be involved in patching or
> >>     issuing new software releases to remote equipment.   XNET seemed
> >>     to them to possibly have something to do with that, hence the
> >>     interest.  The goal was to find hard evidence that such procedures
> >>     were being done by 1980, which would prove that prior art
> >>     existed.  Hard evidence literally means "hard" - opinions help,
> >>     but physical equipment and running code is much more impressive in
> >>     a courtroom.
> >>
> >>     They hadn't found any XNET artifacts, and I couldn't point them to
> >>     any surviving implementations.   But I pointed out that my XNET
> >>     document simply captured the technology that we "stole" from the
> >>     ARPANET IMP experience, and that the IMPs routinely "downloaded
> >>     code" from their neighbors and the NOC all during the life of the
> >>     ARPANET.
> >>
> >>     Since the IMPs had existed since the early 70s, that really
> >>     sparked their interest, and a search (worldwide) ensued to find
> >>     old IMPs, in the hope that just maybe one of them still had the
> >>     IMP software in its magnetic-core memory.  A few IMPs were
> >>     located, but none were functional.  The one in the museum at UCLA
> >>     seemed promising, but the owners were reluctant to even hook it up
> >>     to power after sitting idle for so many years, expecting it might
> >>     go up in smoke.
> >>
> >>     Then I learned from the BBN alumni mailing list that an ancient
> >>     IMP listing had been found in a basement.   The story from that
> >>     point is pretty well described in Dave's paper.
> >>
> >>     Personally, it was an interesting experience.  I worked
> >>     extensively with one lawyer in San Diego.  I taught him how
> >>     computers and networks actually work; he taught me a lot about the
> >>     legal system regarding patents.   IMHO, they are equally
> >>     convoluted and complex when viewed from the other's perspective.
> >>
> >>     I also learned a lot about the IMP code, which I had never even
> >>     looked at while I was at BBN.  One task I took on was to
> >>     exhaustively analyze the parts of the IMP code that implemented
> >>     the "download new instructions" functionality, writing up an
> >>     instruction-by-instruction description of how the code
> >>     accomplished that by interacting with a neighboring IMP.   It was
> >>     a very clever design, and extremely tight code, even including
> >>     self-modifying instructions.   Not easy to figure out (or explain
> >>     in language amenable to a non-technical judge or jury).  So there
> >>     was great interest in being able to demonstrate the code in action
> >>     using real software from the 70s and hardware simulators.
> >>     Tangible evidence is much better than even expert opinions.
> >>
> >>     The whole legal project came to a sudden end just a few months
> >>     prior to the first court date.    I was looking forward to going
> >>     to Delaware (legal action was filed in Federal court in Delaware),
> >>     and finally meeting some of the people.   But the parties settled
> >>     suddenly, the case was dropped, and AFAIK the patent question was
> >>     never resolved.
> >>
> >>     So, that's a bit about the "Why", for history to ponder.    The
> >>     experience got me wondering about the "patent history" of The
> >>     Internet.   Clearly there was a lot of innovation in those days.
> >>     My recollection is that very little was patented, even if only to
> >>     make sure no one else could.   Maybe someone will document the
> >>     patent-related aspects of Internet History someday.
> >>
> >>     /Jack Haverty
> >>
> >>
> >>
> >>     On 9/6/20 12:34 AM, the keyboard of geoff goodfellow wrote:
> >>>     jack, you've raised my curiosity with respect to:
> >>>
> >>>         ... There
> >>>         *is* ARPANET IMP software which was recently restored and a
> small
> >>>         ARPANET was run using simulated IMP hardware.
> >>>
> >>>     Who/What/When/Where/Why?
> >>>
> >>>     geoff
> >>>
> >>>     On Sat, Sep 5, 2020 at 8:40 PM Jack Haverty via Internet-history
> >>>     <internet-history at elists.isoc.org
> >>>     <mailto:internet-history at elists.isoc.org>> wrote:
> >>>
> >>>         Lukasz,
> >>>
> >>>         I think that the earliest implementations of TTL called it
> >>>         "Time", but
> >>>         I'm not aware that anyone actually used time per se in
> >>>         gateways, at
> >>>         least in the early days (1977-1982 or so).
> >>>
> >>>         TCP implementations didn't do anything with TTL other than
> >>>         set it on
> >>>         outgoing datagrams, and at least in my implementation (TCP
> >>>         for Unix), it
> >>>         was just set to some arbitrary value.  Until we had some data
> >>>         from
> >>>         experimentation it was hard to evaluate ideas about what
> >>>         routers, hosts,
> >>>         et al should actually do.   The early TCPs did use time in
> >>>         handling
> >>>         retransmission timers, and there was work a bit later to
> >>>         incorporate
> >>>         time more powerfully into TCP behavior, e.g., Van Jacobson's
> >>>         work.
> >>>
> >>>         The early gateways, IIRC, used the terminology "time", but in
> >>>         practice
> >>>         used just hop counts, since time measurements were difficult to
> >>>         implement.   The exception to that may be Dave Mills'
> >>>         Fuzzballs, since
> >>>         Dave was the implementor most interested in time and making
> >>>         precise
> >>>         measurements of network behavior.   I *think* Dave may have
> >>>         used time
> >>>         values and delay-based routing amongst his "fuzzies".
> >>>
> >>>         The BBN doc you're seeking might have been one of many that
> >>>         discussed
> >>>         the ARPANET internal mechanisms, e.g., ones with titles like
> >>>         "Routing
> >>>         Algorithm Improvements".  The ARPANET internal mechanisms did
> >>>         use time.
> >>>         It was fairly simple in the IMPs, since the delay introduced
> >>>         by the
> >>>         synchronous communications lines could be easily predicted,
> >>>         and the
> >>>         other major component of delay was the time spent in queues,
> >>>         which could
> >>>         be measured fairly easily.
> >>>
> >>>         I even found one BBN ARPANET Project QTR from circa 1975 that
> >>>         discussed
> >>>         the merits of the new-fangled TCP proposal that some
> >>>         professor had
> >>>         published -- and seemed to conclude it couldn't possibly work.
> >>>
> >>>         My involvement in implementations of TCPs and gateways lasted
> >>>         through
> >>>         about mid-1983, so I don't know much of the detail of
> subsequent
> >>>         implementations.  For the various BBN gateway/router
> >>>         equipment, Bob
> >>>         Hinden would probably be a good source.  The other major
> >>>         early player
> >>>         was MIT and spinoffs (Proteon), which perhaps Noel Chiappa will
> >>>         remember.   There's also at least one paper on the Fuzzballs
> >>>         which may
> >>>         have some details.
> >>>
> >>>         One thing I'd advise being careful of is the various
> >>>         "specifications" in
> >>>         RFCs.  Much of the wording in those was intentionally
> >>>         non-prescriptive
> >>>         (use of "should" or "may" instead of "must"), to provide as
> much
> >>>         latitude as possible for experimentation with new ideas,
> >>>         especially
> >>>         within an AS.   The Internet was an Experiment.
> >>>
> >>>         Also, there was no consistent enforcement mechanism to assure
> >>>         that
> >>>         implementations actually even conformed to the "must"
> >>>         elements.   So
> >>>         Reality could be very different from Specification.
> >>>
> >>>         I don't know of any gateway implementations that have
> >>>         survived.   There
> >>>         *is* ARPANET IMP software which was recently restored and a
> small
> >>>         ARPANET was run using simulated IMP hardware.   I still have
> >>>         a ~1979
> >>>         listing of the TCP I wrote for Unix, but haven't scanned it
> >>>         into digital
> >>>         form yet.
> >>>
> >>>         Jack
> >>>
> >>>         On 9/5/20 7:38 PM, Łukasz Bromirski wrote:
> >>>         > Jack,
> >>>         >
> >>>         > I was reading a lot of old BBN PDFs thanks to all good souls
> on
> >>>         > this list that post nice URLs from time to time.
> >>>         >
> >>>         > I remember reading in at least one of them, that apparently
> >>>         first
> >>>         > TCP/IP implementations were indeed using TTL as literally
> >>>         “time”,
> >>>         > not hop count. I believe there somewhere there between PDP
> docs
> >>>         > and ARPANET docs I’ve read something to the effect “and
> >>>         from this
> >>>         > time we changed from measuring time to simply count routing
> >>>         hops”.
> >>>         > Of course, right now google-fu is failing me.
> >>>         >
> >>>         > Quoting RFC 1009 that was already brought up, there’s quite
> >>>         > direct “definition” of the field:
> >>>         >
> >>>         > "4.8.  Time-To-Live
> >>>         >
> >>>         >  The Time-to-Live (TTL) field of the IP header is defined
> >>>         to be a
> >>>         >  timer limiting the lifetime of a datagram in the
> >>>         Internet.  It is
> >>>         >  an 8-bit field and the units are seconds.  This would
> >>>         imply that
> >>>         >  for a maximum TTL of 255 a datagram would time-out after
> >>>         about 4
> >>>         >  and a quarter minutes.  Another aspect of the definition
> >>>         requires
> >>>         >  each gateway (or other module) that handles a datagram to
> >>>         >  decrement the TTL by at least one, even if the elapsed
> >>>         time was
> >>>         >  much less than a second.  Since this is very often the
> >>>         case, the
> >>>         >  TTL effectively becomes a hop count limit on how far a
> >>>         datagram
> >>>         >  can propagate through the Internet."
> >>>         >
> >>>         > Were there any implementations that survived somewhere and
> >>>         actually
> >>>         > did exactly that - counted actual time/processing delay,
> >>>         not hops?
> >>>         > And if it took 2s to process packet, did they really
> >>>         decrement TTL
> >>>         > by two?
> >>>         >
> >>>         > Thanks for any pointers,
> >>>
> >>>         --
> >>>         Internet-history mailing list
> >>>         Internet-history at elists.isoc.org
> >>>         <mailto:Internet-history at elists.isoc.org>
> >>>         https://elists.isoc.org/mailman/listinfo/internet-history
> >>>
> >>>
> >>>
> >>>     --
> >>>     Geoff.Goodfellow at iconia.com <mailto:Geoff.Goodfellow at iconia.com>
> >>>     living as The Truth is True
> >>>
> >>>
> >>>
> >>
> >>
> >> --
> >> Geoff.Goodfellow at iconia.com <mailto:Geoff.Goodfellow at iconia.com>
> >> living as The Truth is True
> >>
> >>
> >>
>
> --
> Internet-history mailing list
> Internet-history at elists.isoc.org
> https://elists.isoc.org/mailman/listinfo/internet-history
>


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