[ih] Significant milestones in the history of TCP/IP

[Bradley Fidler]

I should have clarified that for the IMP program simulation and what we
might learn from it, I was largely talking about ARPANET history, including
some questions posed earlier in this thread, as well as an aside about
method.

I think Vint's comment reminds us of the different categories of TCP /
TCP/IP / vX milestones and how they implicate different things.  Beyond
design and specification milestones, there's other technical matters like
implementations, spread, and performance; here we might be discussing a
_number_ of networks.  Or we might not.  This gets back to one of Dave's
initial questions: which milestones were seminal?

Brad


On 17 September 2015 at 15:57, Vint Cerf <vint at google.com> wrote:

> for all practical purposes, the operation of the IMPs had little to do
> with the design of TCP except for the fact that TCP did not assume one
> message at a time regime that was part of the 1822 IMP/Host interface
> specification.
>
> v
>
>
> On Thu, Sep 17, 2015 at 6:35 PM, Bradley Fidler <fidler at ucla.edu> wrote:
>
>> Are there other historical questions that might be answered using the IMP
>> Guys' article (http://walden-family.com/bbn/imp-code.pdf) and method as
>> a starting-point?  Maybe with an expanded version of the IMP program
>> simulation, if someone were interested?
>>
>> For example, if we knew less about the IMP software -- if what Dave wrote
>> below wasn't widely known -- then the simulation might have been a great
>> way to test the impact of line speeds and thus how different ideas
>> contributed to the initial design.
>>
>> As another example, consider the impact of congestion on the routing
>> algorithm.  The improvements to the algorithm over time are documented in
>> BBN reports, and in part through this documentation we also know that some
>> of these problems were discovered as a consequence of increasing traffic
>> and (if I recall correctly) node count.  It would be great to be able to
>> model the response of given versions of the routing algorithm to increased
>> traffic and network size.  It would require a lot of assumptions, to be
>> sure, but there is a bit published on the distribution of hop counts,
>> packet size, etc. of which someone could make use.  More speculatively, I
>> also wonder if there's enough complaining about congestion on extant
>> listserv archives from the 1980s to combine it with network maps in order
>> to generate some findings on how much traffic might have been common at the
>> time -- and then some even more speculative (but better than nothing!)
>> findings on user counts based on estimates of traffic per user.  Perhaps we
>> already have good congestion figures in the NIC archive at CHM, though, or
>> somewhere else...  In any case, this is just one off-the-cuff example.  Can
>> anyone think of others?
>>
>> This isn't to fetishize the ARPANET, but to point out one possible way to
>> learn more about the interplay of these or other factors in the histories
>> of networking.  One advantage of modeling ARPANET things is that the
>> findings could apply in part to the many networks that were largely ARPANET
>> clones.
>>
>> Brad
>>
>>
>>
>> On 17 September 2015 at 14:23, <dave.walden.family at gmail.com> wrote:
>>
>>> As Bob Armstrong knows, the IMP code (from 1973 or there abouts) that
>>> Bob simulated was highly tuned for the actual line speeds of the net.
>>> Maybe the code knew about something less than 56KBS (I'd have to study the
>>> listing).  Also the IMP knew of a maximum of 5 inter-IMP modem interfaces,
>>> and I don't think it ever used more than 4 and I think option for the 5th
>>> doesn't work (at least in the simulated version, and likely in the real
>>> code).  Thus simulating lots of low speed lines might require modifying the
>>> IMP assembly code.
>>>
>>> Sent from my iPad
>>>
>>> On Sep 17, 2015, at 4:14 PM, Jacob Goense <dugo at xs4all.nl> wrote:
>>>
>>> > On 2015-09-17 19:11, jnc at mercury.lcs.mit.edu wrote:
>>> >> I suspect the only way to say with any certainty how well a network
>>> >> built out
>>> >> of lots of slow lines, as opposed to a few fast ones, would have
>>> worked
>>> >> is a
>>> >> comprehensive simulation. Which is not likely to happen, of course!
>>> ;-)
>>> >
>>> > Well, there is an ARPAnet IMP in simh now. According to Bob Armstrong..
>>> >
>>> > "The hooks are in there to allow simh to support the IMP side of the
>>> > 1822 host interface, and the next step would be to recover the OS for
>>> > an ARPAnet era host and then extend the corresponding simulator to talk
>>> > to the IMP simulation."
>>> >
>>> >
>>> >
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>>
>>
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