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