[Bloat] starlink bloat in review

Neal Cardwell ncardwell at google.com
Mon May 17 11:08:25 EDT 2021


On Sat, May 15, 2021 at 7:00 PM Matt Mathis via Bloat
<bloat at lists.bufferbloat.net> wrote:
>
> I don't understand: starlink doesn't terminate the TCP connection,
> does it?   Or are you referring to YT's BBR adequately addressing
> Starlinks variable RTT?   "Adequately" is probably the operative word.
> It is not too hard to imagine what goes wrong with BBR if the actual
> path length varies, and on an underloaded network, you may not be able
> to even detect the symptoms.

On that note, the article mentions:
  "Starlink itself measures ping times for Counter-Strike: Go and
Fortnite in its app, and I rarely saw those numbers dip below 50ms,
mostly hovering around 85-115ms."

If the range 50ms to 115ms is representative of two-way propagation
delays on their network, then it sounds like BBR can probably perform
reasonably well in that environment. The algorithm is designed to
tolerate factor-of-two variations in RTT and still maintain full
utilization, if there is reasonable buffering.

neal


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