Re: [Starlink] Starlink in Kiribati

[Michael Richardson <mcr@sandelman.ca>]

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Ulrich Speidel via Starlink <starlink@lists.bufferbloat.net> wrote:
    > All traces (to NZ, Chile, the US, Germany and Japan) exited the SpaceX
    > address space in New Zealand to a variety of upstream providers. IP
    > addresses on the Starlink side of the trace beyond Dishy are, in order of
    > appearance in the traces: 100.64.0.1, 172.16.249.6, followed by 149.19.109.30
    > if exiting to Hurricane Electric as upstream or 149.19.109.34 if exiting to
    > Kinect. All those addresses have RTT indicating that they are in NZ.

What are you being NAT44'ed to?
Presumably, that IP is in NZ, and you could traceroute/ping back to it from
elsewhere to be able to subject whatever congestion is beyond the peering point.

    > Lowest RTT seen to the first NZ hop was 65 ms, with values between 100 and
    > 200 ms being the most common.

    > RTTs to the US were mostly in the high 200 ms.

    > 2) The fact that we don't see more than the "usual" number of Starlink IP
    > addresses in the tracreroutes indicates that whatever IP routing may be
    > happening on satellites that handle the traffic via ISLs happens at a tunnel
    > layer further down the stack.

Given Musk's age old tweet that it was "simpler than IPv6", and that we know
that it's some kind of broadcom SDN chipset, this makes sense.
I wish they had used SR6, and done IPv4 as a service.

    > 3) The fact that the traffic emerges in New Zealand regardless of global
    > destination also indicates that the Starlink network uses a tunnel based
    > on Dishy location and a nearby gateway but does not attempt to route to final
    > destination at this point in time.

I'm not surprised about this.
I don't imagine they can world-wide stuff until all the non-ISL birds have aged out.

    > The 65 ms RTT also tells us a few things. For one, at 4,200 km great circle
    > distance on the ground, the dishy-to-gateway physical path would be at least
    > 5,000 km even if all lined up with a polar orbital plane involved. That makes
    > 10,000 km of RTT path, which translates into about 33 ms of propagation
    > RTT. If cross-plane routing were involved here, we'd get a zig-zag path - so
    > roughly 1 1/2 times longer. Makes about 50 ms. In-plane only routing would
    > involve a gateway in Australia (similar length physical path dishy to
    > gateway) along with a 2,000 km trans-Tasman cable leg. The 2000 km cable leg
    > would be equivalent to about 20 ms of additional RTT over the 10,000 km space
    > RTT path, so that could in principle also work. Quite why everything would
    > emerge in Auckland though in this case would be a mystery to me.

I think you are saying that the your lowest RTT of 65ms is easily supported
by physical distances alone?
And that it can't get better.




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