[Starlink] some details on the DTN, bundle protocol, and a capacity question

[Vint Cerf]

we have the most experience with the ION version of BPv7

v


On Sun, Dec 12, 2021 at 7:06 PM Dave Taht <dave.taht at gmail.com> wrote:

> On Sat, Dec 11, 2021 at 7:15 PM Vint Cerf <vint at google.com> wrote:
> >
> > I haven't pushed to much further until we get some real data from
> running implementations. I also hope we can develop a simulator from which
> we might derive measurements to compare with actual data and modeled
> (queueing theoretic) data.
>
> I am just going to ignore the way this thread went for now. What I was
> mostly asking was what version of dtn was the most promising for an
> embedded (e.g. cerowrt  II) implementation?
>
> https://dtn7.github.io/ looks very promising, especially the rust
> bits. Rust lets me sleep better and we are moving some support for it
> into openwrt's next release.
>
>  https://github.com/morgenroth/ibrdtn  is undermaintained but was
> already ported to openwrt, and is lighter weight. There's another one
> targetted at microcontrollers (  https://upcn.eu/ ), but not the FRAM
> one we used on a previous space-related project... really liked those
> FRAMs....
>
> As for the simulator side, what/where are the requirements? I confess
> to wanting to feed forward the asterank, or celestia, or nasa's new
> https://eyes.nasa.gov/apps/asteroids/#/asteroids into it another 10
> years and plunk 28k nodes into it....
>
>
>
>
>
> > v
> >
> >
> > On Sat, Dec 11, 2021 at 9:58 PM Dave Taht <dave.taht at gmail.com> wrote:
> >>
> >> A good deep dive into DTN with vint cerf is here:
> >>
> https://www.datacenterdynamics.com/en/analysis/vint-cerfs-interplanetary-ambitions/
> >>
> >>  I went looking for existing source code for it, some here:
> >> https://projet.liris.cnrs.fr/riot/dtn_implementations_survey.html
> >>
> >> From the interview...
> >>
> >> Q: "So for store and forward to work, what is the level of storage
> >> each node needs to the speed of the network?"
> >>
> >> VC: That's such a good question. So guess what, I have the same
> >> question. And I said, 'Okay, where do I go to get an answer to that?'
> >> And that is the capacity question: What capacity of this DTN network,
> >> given if I know where the nodes are, and I know what the physics are.
> >> And I know what the data rates could be. I have a traffic matrix. Do I
> >> have a network which is capable of supporting the demand?
> >>
> >> That's the formulation of the question you're asking. So I went to the
> >> best possible source for this question, Leonard Kleinrock at UCLA. He
> >> is the father of the use of queueing theory to analyze store and
> >> forward networks way back in 1961/62, doing his dissertation at MIT on
> >> this topic, not in aid of the interplanetary network, but more general
> >> question on store and forward networking.
> >>
> >> And so he did some fantastic work, he broke the back of the problem
> >> with what was called the independence principle. But he left MIT and
> >> came to UCLA in the '60s, he was on my thesis committee. And he's
> >> still very, very active. He's 87, still blasting on.
> >>
> >> So I sent him a note saying, look, here's the problem. I've got this
> >> collection of notes, and I've got a traffic matrix, and I have this
> >> DTN environment, how do I calculate the capacity of the system so I
> >> know, I'm not gonna overwhelm it.
> >>
> >> And, you know, I figured it would take him a while and maybe find a
> >> graduate student. So *two days later*, I get back two pages of dense
> >> math saying, okay, here's how you formulate this problem. Now, I
> >> didn't get all of the answer. I still don't have all of the answer.
> >> But I know I have one of the best minds in the business looking at the
> >> problem."
> >>
> >> That was back in august of this year, made any progress?
> >>
> >> --
> >> I tried to build a better future, a few times:
> >> https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org
> >>
> >> Dave Täht CEO, TekLibre, LLC
> >> _______________________________________________
> >> Starlink mailing list
> >> Starlink at lists.bufferbloat.net
> >> https://lists.bufferbloat.net/listinfo/starlink
> >
> >
> >
> > --
> > Please send any postal/overnight deliveries to:
> > Vint Cerf
> > 1435 Woodhurst Blvd
> > McLean, VA 22102
> > 703-448-0965 <(703)%20448-0965>
> >
> > until further notice
> >
> >
> >
>
>
> --
> I tried to build a better future, a few times:
> https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org
>
> Dave Täht CEO, TekLibre, LLC
>


-- 
Please send any postal/overnight deliveries to:
Vint Cerf
1435 Woodhurst Blvd
McLean, VA 22102
703-448-0965

until further notice
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