Starlink routing

Mon Jan 23 20:18:18 UTC 2023

(inline)

On Sun, Jan 22, 2023 at 4:44 PM Michael Thomas <mike at mtcc.com> wrote:

the ability to route messages between each satellite. Would conventional
>> routing protocols be up to such a challenge?
>
>
If conventional is taken to mean "stock" link-state stuff, then probably no
(speculating).

> 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?
>>
>
As others might comment, "it's all been done (and modeled) before," or "we
tried it 20 years ago, and it worked then" - more inline here:

On Sun, Jan 22, 2023 at 5:06 PM Matthew Petach <mpetach at netflight.com>
wrote:

> 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.
>

Lest we forget: Ad hoc On-Demand Distance Vector (AODV) Routing, and its
many offspring. Coming up on 20 years of service. Found its way into a lot
of stuff, specifically zigbee and IoT-galore. Power-efficiency is the
primary goal here.

Hazy Sighted Link State Routing Protocol (HSLS) - teaches us that if we can
have higher-rate updates, and introduce some clever "Fish Eye" update
filtering, then graph scaling can result. In HSLS, a network graph shrinks
to O(N^1.5), versus an unaided O(N^2). Not a log, but close enough for ~4k
nodes to use a state space of ~2^18.

I'm not picking 4k as a random example here. Also note that as of Dec 2022,
Startlink has over 3,300 launched satellites. Depending on data structures
used by an implementer, the whole thing could reside in SRAMs. Would be a
no-brainer, even in RL-DRAMs, etc. too.

To appreciate where this work has been, check out this 20-year-old
introduction, covering an implementation of Fish Eye for OLSR:
https://www.thomasclausen.net/wp-content/uploads/2015/12/2004-JCN-Fish-Eye-OLSR-Scaling-Properties.pdf
- skip the end to see where the HSLS capacity curve receeds, and where the
Fish Eye-enhanced approach continues to find new capacity.

-Tk
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