Re: Starlink routing

[Tom Beecher <beecher () beecher cc>]

Yes re: Iridium. Contrary to what the Chief Huckster may say, inter-sat
comms are not some revolutionary thing that he invented.

It’s also not likely to function anything like they show in marketing
promos, with data magically zipping around the constellation between nodes
in different inclinations. Unless they have managed to solve for the
Doppler effect in a way nobody has thought of yet.


On Sun, Jan 22, 2023 at 18:25 Crist Clark <cjc+nanog () pumpky net> wrote:

> I suspect, although I have no references, that satellite to ground
> connectivity is probably more “circuit-based” than per-packet or frame.
>
> Iridium has done inter satellite communication for decades. I wonder if it
> wouldn’t be something very similar. Although it would be totally on-brand
> for them to do it some “revolutionary” new way whether it actually makes
> any sense or not.
>
>
> On Sun, Jan 22, 2023 at 3:06 PM Matthew Petach <mpetach () netflight com>
> wrote:
>
> > On Sun, Jan 22, 2023 at 2:45 PM Michael Thomas <mike () mtcc com> wrote:
> >
> > > I read in the Economist that the gen of starlink satellites will have
> > > the ability to route messages between each satellite. Would conventional
> > > routing protocols be up to such a challenge? Or would it have to be
> > > custom made for that problem? And since a lot of companies and countries
> > > are getting on that action, it seems like fertile ground for (bad) wheel
> > > reinvention?
> > >
> > > Mike
> >
> > Unlike most terrestrial links, the distances between satellites are not
> > fixed,
> > and thus the latency between nodes is variable, making the concept of
> > "Shortest Path First" calculation a much more dynamic and challenging
> > one to keep current, as the latency along a path may be constantly
> > changing
> > as the satellite nodes move relative to each other, without any link
> > state actually
> > changing to trigger a new SPF calculation.
> >
> > I suspect a form of OLSR might be more advantageous in a dynamic partial
> > mesh between satellites, but I haven't given it as much deep thought as
> > would
> > be necessary to form an informed opinion.
> >
> > So, yes--it's likely the routing protocol used will not be entirely
> > "off-the-shelf"
> > but will instead incorporate continuous latency information in the LSDB,
> > and path selection will be time-bound based on the rate of increase in
> > latency
> > along currently-selected edges in the graph.
> >
> > An interesting problem to dive into, certainly.   :)
> >
> > Thanks!
> >
> > Matt