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

[Jonathan Morton]

> 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.

 - Jonathan Morton