[Ecn-sane] [Bloat] dropbox, bbr and ecn packet capture

[Neal Cardwell]

On Sat, Apr 25, 2020 at 8:52 PM Jonathan Morton <chromatix99 at gmail.com>
wrote:

> > On 26 Apr, 2020, at 3:36 am, Dave Taht <dave.taht at gmail.com> wrote:
> >
> > I just did a rather large dropbox download. They are well known to be
> > using bbr and experimenting with bbrv2. So I fired off a capture
> > during a big dropbox download...
> >
> > It negotiated ecn, my fq_codel shaper and/or my newly ath10k
> > fq_codel's wifi exerted CE, osx sent back ecn-echo, and the rtt
> > results were lovely. However, there is possibly not a causal
> > relationship here, and if anyone is bored and wants to scetrace,
> > tcptrace or otherwise tear this cap apart, go for it.
>
> Well, the CE response at their end is definitely not Multiplicative
> Decrease.  I haven't dug into it more deeply than that.  But they're also
> not running AccECN, nor are they "proactively" sending CWR to get a "more
> accurate" CE feedback.  I suspect they're running BBRv1 in this one.


Agreed, that looks like BBRv1. I see a few BBRv1 PROBE_RTT phases in there.

Thanks for the trace!

best,
neal
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