On Sat, Apr 25, 2020 at 8:52 PM Jonathan Morton <chromatix99@gmail.com> wrote:
> On 26 Apr, 2020, at 3:36 am, Dave Taht <dave.taht@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