[Cake] [lede-project/source] Add support for cake qdisc (#72)

[Kevin Darbyshire-Bryant]

On 01/06/16 11:13, Dave Täht wrote:
> I still think squashing is very important, and essentially required by
> several rfcs.




I'm now wondering if we're falling into a terminology trap. The original 
tc/cake implementation of 'squash' was effectively to use 'besteffort' 
(ie diffserv1) ie. ignore the DSCP bits *and* to clear the DSCP bits on 
outgoing 'wash'.

I (foolishly?) split out the DSCP washing feature to a separate 
controllable flag - wash/nowash*

Thus it is at present possible to use the DSCP bits for diffserv4/5 
differentiation on ingress to the queue but to clear those DSCP bits for 
egress purposes.