[ih] nice story about dave mills and NTP

[Alejandro Acosta]

Hello Jack,

   Thanks a lot for sharing this, as usual, I enjoy this kind of stories :-)

   Jack/group, just a question regarding this topic. When you mentioned:

"This caused a lot of concern about protocol elements such as 
Time-To-Live, which were temporarily to be implemented purely as "hop 
counts"


   Do you mean, the original idea was to really drop the packet at 
certain time, a *real* Time-To-Live concept?.


Thanks,

P.S. That's why it was important to change the field's name to hop count 
in v6 :-)



On 2/10/22 12:35 AM, Jack Haverty via Internet-history wrote:
> On 10/1/22 16:30, vinton cerf via Internet-history wrote:
>> in the New Yorker
>>
>> https://www.newyorker.com/tech/annals-of-technology/the-thorny-problem-of-keeping-the-internets-time 
>>
>>
>> v
>
> Agree, nice story.   Dave did a *lot* of good work.  Reading the 
> article reminded me of the genesis of NTP.
>
> IIRC....
>
> Back in the early days circa 1980, Dave was the unabashed tinkerer, 
> experimenter, and scientist.  Like all good scientists, he wanted to 
> run experiments to explore what the newfangled Internet was doing and 
> test his theories.   To do that required measurements and data.
>
> At the time, BBN was responsible for the "core gateways" that provided 
> most of the long-haul Internet connectivity, e.g., between US west and 
> east coasts and Europe.  There were lots of ideas about how to do 
> things - e.g., strategies for TCP retransmissions, techniques for 
> maintaining dynamic tables of routing information, algorithms for 
> dealing with limited bandwidth and memory, and other such stuff that 
> was all intentionally very loosely defined within the protocols.   The 
> Internet was an Experiment.
>
> I remember talking with Dave back at the early Internet meetings, and 
> his fervor to try things out, and his disappointment at the lack of 
> the core gateway's ability to measure much of anything. In particular, 
> it was difficult to measure how long things took in the Internet, 
> since the gateways didn't even have real-time clocks. This caused a 
> lot of concern about protocol elements such as Time-To-Live, which 
> were temporarily to be implemented purely as "hop counts", pending the 
> introduction of some mechanism for measuring Time into the gateways.  
> (AFAIK, we're still waiting....)
>
> Curiously, in the pre-Internet days of the ARPANET, the ARPANET IMPs 
> did have a pretty good mechanism for measuring time, at least between 
> pairs of IMPs at either end of a communications circuit, because such 
> circuits ran at specific speeds.   So one IMP could tell how long it 
> was taking to communicate with one of its neighbors, and used such 
> data to drive the ARPANET internal routing mechanisms.
>
> In the Internet, gateways couldn't tell how long it took to send a 
> datagram over one of its attached networks.   The networks of the day 
> simply didn't make such information available to its "users" (e.g., a 
> gateway).
>
> But experiments require data, and labs require instruments to collect 
> that data, and Dave wanted to test out lots of ideas, and we (BBN) 
> couldn't offer any hope of such instrumentation in the core gateways 
> any time soon.
>
> So Dave built it.
>
> And that's how NTP got started.  IIRC, the rest of us were all just 
> trying to get the Internet to work at all.   Dave was interested in 
> understanding how and why it worked.  So while he built NTP, that 
> didn't really affect any other projects.  Plus most (at least me) 
> didn't understand how it was possible to get such accurate 
> synchronization when the delays through the Internet mesh were so 
> large and variable.   (I still don't).   But Dave thought it was 
> possible, and that's why your computer, phone, laptop, or whatever 
> know what time it is today.
>
> Dave was responsible for another long-lived element of the Internet.   
> Dave's experiments were sometimes disruptive to the "core" Internet 
> that we were tasked to make a reliable 24x7 service.  Where Dave The 
> Scientist would say "I wonder what happens when I do this..." We The 
> Engineers would say "Don't do that!"
>
> That was the original motivation for creating the notion of 
> "Autonomous Systems" and EGP - a way to insulate the "core" of the 
> Internet from the antics of the Fuzzballs.  I corralled Eric Rosen 
> after one such Fuzzball-triggered incident and we sat down and created 
> ASes, so that we could keep "our" AS running reliably.  It was 
> intended as an interim mechanism until all the experimentation 
> revealed what should be the best algorithms and protocol features to 
> put in the next generation, and the Internet Experiment advanced into 
> a production network service.   We defined ASes and EGP to protect the 
> Internet from Dave's Fuzzball mania.
>
> AFAIK, that hasn't happened yet ... and from that article, Dave is 
> still Experimenting..... and The Internet is still an Experiment.
>
> Fun times,
> Jack Haverty
>