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<div class="moz-cite-prefix">On 22/04/2023 4:11 am, Michael
Richardson wrote:<br>
</div>
<blockquote type="cite" cite="mid:28149.1682093487@localhost">
<br>
Ulrich Speidel via Starlink <a class="moz-txt-link-rfc2396E" href="mailto:starlink@lists.bufferbloat.net"><starlink@lists.bufferbloat.net></a>
wrote:<br>
> All traces (to NZ, Chile, the US, Germany and Japan) exited
the SpaceX<br>
> address space in New Zealand to a variety of upstream
providers. IP<br>
> addresses on the Starlink side of the trace beyond Dishy are,
in order of<br>
> appearance in the traces: <a href="http://100.64.0.1" moz-do-not-send="true">100.64.0.1</a>, 172.16.249.6, followed by
<a href="http://149.19.109.30" moz-do-not-send="true">149.19.109.30</a><br>
> if exiting to Hurricane Electric as upstream or <a href="http://149.19.109.34" moz-do-not-send="true">149.19.109.34</a> if exiting to<br>
> Kinect. All those addresses have RTT indicating that they are
in NZ.<br>
<br>
What are you being NAT44'ed to?<br>
</blockquote>
Good question - can't answer this right now as Dishy is back in its
suitcase in our lab ;-)<br>
<blockquote type="cite" cite="mid:28149.1682093487@localhost">
Presumably, that IP is in NZ, and you could traceroute/ping back
to it from<br>
elsewhere to be able to subject whatever congestion is beyond the
peering point.<br>
</blockquote>
Beyond peering point is an interesting thing, too. We spent a day
this week on a mountain 5 hours drive south of Auckland running
Dishy out of the back of my car, just to find that the one
traceroute we took from there shows a routing issue on the Internet
side of the POP - HE sent traffic from NZ to Australia, from where
it was returned to us, adding over 4000 km of cable to the path each
way. Sigh. Ookla tests (to a different machine in a different
network in NZ) gave around half the download rates we were observing
from the two other locations we visited (and we took 60-180 samples
in each location), where that routing issue didn't show up. <br>
<blockquote type="cite" cite="mid:28149.1682093487@localhost">
<br>
> Lowest RTT seen to the first NZ hop was 65 ms, with values
between 100 and<br>
> 200 ms being the most common.<br>
<br>
> RTTs to the US were mostly in the high 200 ms.<br>
<br>
> 2) The fact that we don't see more than the "usual" number of
Starlink IP<br>
> addresses in the tracreroutes indicates that whatever IP
routing may be<br>
> happening on satellites that handle the traffic via ISLs
happens at a tunnel<br>
> layer further down the stack.<br>
<br>
Given Musk's age old tweet that it was "simpler than IPv6", and
that we know<br>
that it's some kind of broadcom SDN chipset, this makes sense.<br>
I wish they had used SR6, and done IPv4 as a service.<br>
</blockquote>
Indeed, but then who would want to rely on something he said a while
ago?<br>
<blockquote type="cite" cite="mid:28149.1682093487@localhost">
<br>
> 3) The fact that the traffic emerges in New Zealand
regardless of global<br>
> destination also indicates that the Starlink network uses a
tunnel based<br>
> on Dishy location and a nearby gateway but does not attempt
to route to final<br>
> destination at this point in time.<br>
<br>
I'm not surprised about this.<br>
I don't imagine they can world-wide stuff until all the non-ISL
birds have aged out.<br>
</blockquote>
Well, they do have a complete constellation with lasers, and a polar
one that's semi-complete, so in theory they should be able to do
this...<br>
<blockquote type="cite" cite="mid:28149.1682093487@localhost">
<br>
> The 65 ms RTT also tells us a few things. For one, at 4,200
km great circle<br>
> distance on the ground, the dishy-to-gateway physical path
would be at least<br>
> 5,000 km even if all lined up with a polar orbital plane
involved. That makes<br>
> 10,000 km of RTT path, which translates into about 33 ms of
propagation<br>
> RTT. If cross-plane routing were involved here, we'd get a
zig-zag path - so<br>
> roughly 1 1/2 times longer. Makes about 50 ms. In-plane only
routing would<br>
> involve a gateway in Australia (similar length physical path
dishy to<br>
> gateway) along with a 2,000 km trans-Tasman cable leg. The
2000 km cable leg<br>
> would be equivalent to about 20 ms of additional RTT over the
10,000 km space<br>
> RTT path, so that could in principle also work. Quite why
everything would<br>
> emerge in Auckland though in this case would be a mystery to
me.<br>
<br>
I think you are saying that the your lowest RTT of 65ms is easily
supported<br>
by physical distances alone?<br>
And that it can't get better.<br>
</blockquote>
<p>Basically, an observed RTT puts an upper bound on the length of
the possible physical path a packet can have taken. On that basis,
I'm simply looking at potentially feasible paths here. I'm just
observing that if you are landing traffic in Australia where you
have multiple gateways and POPs, it makes little sense to then
also have a terrestrial tunnel to NZ for the traffic that you are
landing and that's destined to other continents. <br>
</p>
<p>I mean, I'd like Auckland to be the navel of the world, but I
somehow doubt that Elon would take the same view ... Then again,
at least one of his Silicon Valley mates got NZ citizenship after
just two weeks in the country. The guy was going to promote this
widely but then somehow that didn't happen and if I correctly
remember, it took an Official Information Act request to find out
that the guy had become a proud Kiwi. FAIK he hasn't spent much if
any time here since becoming a citizen either. So who knows
whether Elon might have a secret bolt hole here? Lots of people
do... </p>
<br>
<pre class="moz-signature" cols="72">--
****************************************************************
Dr. Ulrich Speidel
School of Computer Science
Room 303S.594 (City Campus)
The University of Auckland
<a class="moz-txt-link-abbreviated" href="mailto:u.speidel@auckland.ac.nz">u.speidel@auckland.ac.nz</a>
<a class="moz-txt-link-freetext" href="http://www.cs.auckland.ac.nz/~ulrich/">http://www.cs.auckland.ac.nz/~ulrich/</a>
****************************************************************
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