[e2e] Mixed ECN and Non-ECN traffic flows.

[Christian Huitema]

> I've done some simulations using a mixture of ECN and non-ECN capable
TCP
> flows over NS-2 and I've discovered that at a bottleneck link with a
> single
> FIFO queue, ECN flows tend to grab more than their fair share of the
> bandwidth when an AQM (RED,BLUE) is used at the router.

This looks like a good thing to me. After all, we need some incentive
for people to deploy ECN... As long as the ECN capable flows do not tend
to actually exclude the non ECN flows, I believe that we are fine.

-- Christian Huitema