Starlink routing

Tom Beecher beecher at beecher.cc
Mon Jan 23 16:55:24 UTC 2023


>
> Elon for whatever reason is insane enough to dump a lot of cash in
> industries which everyone said was a dead end and then has been lucky
> enough to prove the old guard wrong.
>

>
- Nobody had 'given up' on reusable launch vehicles. SpaceX (to their
credit) just made it a core requirement in Falcon9 design from the outset,
and was able to execute it.
- Nobody had 'given up' on electric cars before Musk pushed the original
founders of Tesla out.
- Musk took Solarcity in the opposite direction (down) as the rest of the
US solar industry grew.
- Starlink still hasn't proven any of the 'old guard wrong'.  Is Starlink
operational? Yes. Has he proven it to be a viable business? No. (In fact,
if you basic math on the numbers they espouse, it can't be.)

Same for pretty much everything musk does,  including starlink.   So if
> there is anything at all "revolutionary" here it's the insistence on
> ignoring conventional wisdom.   I think it might be borderline insanity,
> but it seems to work for him.


It 'seems to work for him' because :
1. He is a showman, and good at it.
2. When something is delivered, it's only because of him. When something
isn't, it's always because of someone/something else.




On Mon, Jan 23, 2023 at 11:02 AM Forrest Christian (List Account) <
lists at packetflux.com> wrote:

> Like I said,  they're calling it revolutionary.   Didn't say it was.
>
> However the idea that you can build spaceships which are fully reusable
> was certainly around the industry,  but the consensus was largely "we
> tried, it costs too much,  so we're sticking with one use rockets".   Elon
> for whatever reason is insane enough to dump a lot of cash in industries
> which everyone said was a dead end and then has been lucky enough to prove
> the old guard wrong.
>
> Same for pretty much everything musk does,  including starlink.   So if
> there is anything at all "revolutionary" here it's the insistence on
> ignoring conventional wisdom.   I think it might be borderline insanity,
> but it seems to work for him.
>
> On Mon, Jan 23, 2023, 3:46 AM Jorge Amodio <jmamodio at gmail.com> wrote:
>
>>
>> Musk didn't do anything revolutionary, besides launching a shload of LEO
>> satellites.
>>
>> NASA and DoD have been working for long time on optical space
>> communications, last year LCRD was launched and preliminary tests using it
>> as a relay showed 622Mpbs, this year NASA will include on one of the
>> cargo missions to ISS ILLUMA-T that will be installed at ISS and it is
>> expected to provide 1.24Gpbs or more using LCRD as a relay with the two
>> ground stations, one in HI, and one in CA.
>>
>> DoD/NRO have been working on this for some time now, but any information
>> is in the top secret blackhole.
>>
>> -J
>>
>>
>> -Jorge
>>
>> On Jan 23, 2023, at 1:54 AM, Forrest Christian (List Account) <
>> lists at packetflux.com> wrote:
>>
>> 
>> I think the thing they're calling revolutionary is the idea of those
>> links being directional lasers.
>>
>> It makes some sense...  if you can basically emit the same signal you'd
>> shoot down a strand of single mode but aim it through the mostly vacuum of
>> space in the exact direction of your neighbor then you've got something...
>> Essentially the equivalent of a fiber optic network in space.
>>
>> For fun  I tried plugging in some frequencies of light into a doppler
>> calculator.  Unfortunately that's where my "would the relative speed that
>> mere mortals could attain make enough of a difference to affect a typical
>> optical receiver" investigation ended as I'm mobile right now and can't do
>> the rest of the work very easily.   I'd be curious if the relative speed
>> would be enough to cause enough shift to move it out of the pass band if a
>> typical dwdm channel.
>>
>> And, I agree that little of what musk takes credit for is revolutionary.
>> But what I do think he deserves credit for is being insane enough to try
>> things everyone says is unworkable and failed in the past and somehow
>> making at least some of them work.  Having more money than God helps too.
>>
>>
>>
>> On Sun, Jan 22, 2023, 8:55 PM Tom Beecher <beecher at beecher.cc> wrote:
>>
>>> 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 at 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 at netflight.com>
>>>> wrote:
>>>>
>>>>>
>>>>>
>>>>> On Sun, Jan 22, 2023 at 2:45 PM Michael Thomas <mike at 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
>>>>>
>>>>>
>>>>
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