[Cake] Upstream submission of dual-mode fairness patch

[Jonathan Morton]

> On 3 Mar, 2019, at 6:35 pm, Pete Heist <pete at heistp.net> wrote:
> 
> It almost seems like in ingress mode, dropped packets are being counted as bytes transferred, when they weren’t.

Well yes, that's the whole point - at least as far as the shaper is concerned.  Ingress mode is supposed to deal with the case where inbound packets have already traversed the bottleneck link *before* Cake gets to choose what to do with them.

But that shouldn't affect fairness, only total throughput.  Fairness is not handled by the shaper, but by the (very) extended DRR++ algorithm.

 - Jonathan Morton