I believe that I read that STarlink has 5 lasers per sat. but whatever the
number, it's a tiny number compared to the number of satellites that they have
up there.
As you are looking at 'trains', check their altitude. They aren't going to
shuffle sats around much, it's expensive in terms of fuel and they are only
allowed to provide service when they are in their proper orbits.
We know the lasers are in operation as they are providing service to places more
than one sat hop away from ground stations. We also know they have a lot of
ground stations around to share the load.
We have almost no details on the specific modules they are using, and none on
what routing they are using.
David Lang
On Fri, 22 Sep 2023,
Alexandre Petrescu via Starlink wrote:
Date: Fri, 22 Sep 2023 10:26:26 +0200
From: Alexandre Petrescu via Starlink <starlink@lists.bufferbloat.net>
Reply-To: Alexandre Petrescu <alexandre.petre...@gmail.com>
To: starlink@lists.bufferbloat.net
Subject: Re: [Starlink] APNIC56 last week
Le 21/09/2023 à 21:05, Inemesit Affia via Starlink a écrit :
Not going to go into details but lasers have been identified in photos
of the sats and one of the component suppliers is known. (The scale is
novel, not the tech, demisabiliy is new though)
4 or 2 lasers on each sat (N-S, E-W) is potentially a very different
matter from an IP routing standpoint. It still is a reduced set of
variables, for a routing protocol (it is not like there being an
arbitrary number of IP interfaces, it's just 2 or 4).
For component manufacturers: yes, I heard about a few manufacturers of
such equipment for laser comms for LEO sats, experimented. There is
public information about a few of them. I dont know which is considered
by starlink, but there is not my worry. There is also a difference
between laser links between sats on different orbit altitudes (e.g.
laser for ISL for GEO to MEO) and lasers between sats on a same orbit
altitude, or on a same orbit. It's three different things, with
different sets of requirements: focusing, power levels, distance ranges.
At the lowest limit (cheapest, less powerful, less range distance), I
suppose it is possible to use simply LiFi optical links (a sort of WiFi
but with light). If so, then it is very easy to have IP on it.
There is also an 'optical' spec that was circulated here on this list
(https://www.sda.mil/wp-content/uploads/2022/04/SDA-OCT-Standard-v3.0.pdf),
although it seemed to me to figure on kepler's website, not on
starlink's. In that spec, it is said Ethernet, among other things. On
Ethernet, IP can run easily.
Starlink can't deliver to Antarctica or Northern parts of Alaska,
Ascension Island, Diego Garcia, Easter Island, Vanuatu, Iran without
ISL's etc
I'll have to look where these places are.
When looking at starlink satellites I often see trains forming and
lasting for a while. Someone said these sats are like that (trains)
prior to be put on a more evenly distanced, in-orbit; but some time
passed, and they continue this kind of behaviour: form denser trains,
then distance more evenly, and back again. So I am not sure these
'trains' are ephemeral. They seem to be in such 'train' structure while
above some particular continents or areas, but not sure. It takes a lot
of time to make a meaning of it.
Also, now here are at least two kinds of starlink subscription plans:
40EUR/month and 287EUR/month, for fixed vs mobile.
North South links seem to work but not East West (if they exist)
Yes, good question. It makes a lot of difference whether there are 2 or
4 laser links on each sat. It also makes a lot of difference if trying
to make IP routing work there (assuming there could be 2 or 4 IP
interfaces for lasers).
This (number of ISL links on a starlink sat) can have an impact on how
people show LEO satellite topologies in Internet Drafts at IETF.
Alex
On Thu, Sep 21, 2023, 2:20 PM Alexandre Petrescu via Starlink
<starlink@lists.bufferbloat.net> wrote:
Le 19/09/2023 à 06:39, Ulrich Speidel via Starlink a écrit :
> FWIW, I gave a talk about Starlink - insights from a year in -
at last
> week's APNIC56 conference in Kyoto:
>
> https://conference.apnic.net/56/program/program/#/day/6/technical-2/
Thanks for the presentation.
I would like to ask what do you mean by "Method #2: "space
lasers""and
"Not all Starlink satellites have
lasers" on slide 5?
It seems to be saying there is inter-satellite communications. The
need
of that seems to stem from the lack of ground 'teleport' that is
necessary for DISHY-SAT-Internet communications, so a SAT-to-SAT
communication is apparently used with lasers. I can agree with
the need.
What standard is used for these lasers?
Is this ISL communicaiton within the starlink constellation a
supposition or a sure thing?
Other presentations of starlink mentioned on this list dont talk
about
this lasers between sats (dont show lasers on the sats), but kepler
talks about optical links, and also there is talk about ISOC LEO
Internet about such 'lasers from space'.
(I must say that I thought previously that there were only 2 or 3
ground
teleports overall in EU and USA, but I see now there is a teleport
in NZ
too).
(for price comparison: it is said 100USD monthly, but in France right
now the monthly subscription is at around 40 Euros; this competes
very
advantageously to other satcoms ISPs for rural areas non-covered
by 5G;
the cellular monthly subscriptions are still much more advantageous,
where there is 5G, of course).
Alex
>
> Also well worth looking at is Geoff Huston's excellent piece on the
> foreseeable demise of TCP in favour of QUIC in the same session.
One
> of Geoff's main arguments is that the Internet is becoming local,
> i.e., most traffic goes between a CDN server and you, and most
data is
> becoming proprietary to the application owner, meaning it suits the
> Googles and Facebooks of this world very well not to be using
TCP for
> its transport, but rather pull the transport specifics into the
> application layer where the have full control.
>
> Food for thought, especially since LEO networks are a
particularly bad
> place to put local content caches, since the concept of what's
"local"
> in a LEO network changes constantly, at around 20,000 miles an
hour or
> so. Spoke to a Rwandan colleague who installs Starlink there and
sees
> all traffic to anywhere go via the US with RTTs of nearly 2
seconds,
> even if the Rwandan user is trying to access a Rwandan service.
>
> About to hop onto a plane (ZK-NZJ) tonight with free WiFi (Ka band
> GEO) enroute to Auckland in the hope of getting a better experience
> than last time when the system seemed to run out of IP addresses on
> its DHCP.
>
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