This technical paper on Starlink by the chief scientist at APNIC crossed my
feed this week. [I thought I'd share it to the Starlink list here but my
application to join that list seems to have gotten stuck so I'll share it
here for now.]
<https://www.potaroo.net/ispcol/2024-05/starlink-tcp.html>
From the end of the paper:
While earlier TCP control protocols, such as Reno, have been observed to
perform poorly on Starlink connections, more recent TCP counterparts,
such as CUBIC, perform more efficiently. The major TCP feature that makes
these protocols viable in Starlink contexts is the use of Selective
Acknowledgement [11], that allows the TCP control algorithm to
distinguish between isolated packet loss and loss-inducing levels of
network congestion.
TCP control protocols that attempt to detect the onset of network queue
formation can do so using end-to-end techniques by detecting changes in
end-to-end latency during intermittent periods of burst, such as BBR.
These protocols need to operate with a careful implementation of their
sensitivity to latency, as the highly unstable short-term latency seen on
Starlink connections, coupled with the 15-second coarse level latency
shifts have the potential to confuse the queue onset detection algorithm.
It would be interesting to observe the behaviour of an ECN-aware TCP
protocol behaviour if ECN were to enabled on Starlink routing devices.
ECN has the potential to provide a clear signal to the endpoints about
the onset of network-level queue formation, as distinct from latency
variation.
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