I have put up screenshots of tcptrace -G and xplot.org's analysis of my
most recent capture of an ipv6 connection over freebox (wired) from a
debloat-testing kernel here in france (pre 3.1 by a lot) to a 2.6.16
kernel (the aformentioned netsonar box) in redwood city, ca, both
running tcp cubic, over ipv6.

at first glance, it looked a lot like a classic bufferbloat trace, with
complete with periodic collapses and cubic increasing the window.

Then I noticed the sacks.

I also have a trace taken between the debloat-testing box and a cerowrt
box (running linux 3.04), both running westwood, which shows
considerably less undesirable behavior, and I will repeat that test with
cubic this evening and post additional data tomorrow morning.

-- 
Dave Täht