Re: [Rpm] Outch! I found a problem with responsiveness

[Simon Leinen <simon.leinen@switch.ch>]

Hallo Christoph,

> That's right. BB is a transient problem that is extremely short-lived.

> Having tried for the past year to reliably demo the user-visible
> impact of bufferbloat, I have learned two things:

> 1. When it happens, it is bad - really bad.
> 2. However, it is very difficult to trigger it "on-demand".

I seem to be able to trigger it quite reliably by using mobile data
while traveling on the train and doing normal remote work.  Here in
Switzerland I often see RTTs in excess of 10 seconds.  In France I have
seen more than two MINUTES.

Maybe I should start setting up systematic measurements.  For example,
if I just sent pings both from my laptop to a well-connected fixed host,
and vice-versa, while capturing all ICMP packets on both ends, I should
be able to learn about bufferbloat in both directions.

It would be even better to have this in a mobile (web) app that could
record/send location data from the mobile node, to spot the regions
(presumably around tunnels and other connectivity-challenged areas)
where the problem tends to occur most often.  Alternatively, correlate
the probe timestamps with real-time location data provided by the
railway company.

Cheers,
-- 
Simon.