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

[moeller0]

Hi Toke,

> On Jun 1, 2016, at 13:20 , Toke Høiland-Jørgensen <toke at toke.dk> wrote:
> 
> moeller0 <moeller0 at gmx.de> writes:
> 
>> So, my take on this is that we want to be able to re-map DSCP to zero. On
>> ingress if we do not trust our upstream to do the right thing on egress if we do
>> not want to leak internal information to our upstream. As far as I can tell DSCP
>> is supposed to be domain specific and I consider a home net equivalent with a
>> domain. This is why I tried to argue for the existing squash/wash combination.
>> Since Dave had already implemented the squashing on ingress per iptables in SQM,
>> we will still be able to offer this functionality in SQM independent on whether
>> cake offers this natively or not (but note the sqm implementation re-mapped
>> after using the DSCP marks)*. I tried to divine which mis-feature Jonathan
>> referred to and remembered his unhappiness with that feature, and since I really
>> want to see cake go somewhere I am fine with “sacrificing” this feature to make
>> upstreaming more likely.
> 
> I'm guessing this was probably discussed before and I've simply
> forgotten; but why does this (rewriting dscp bits) need to be part of
> the qdisc when you can do it with iptables?

	Well, cake looks at the DSCP bits already, if it can do the re-mapping we potentially would not need to touch iptables at all, which cakes goal being simplicity seemed on-focus. But since this feature turned out to be contentious, I vote for throwing it out and just rely on iptables… I believe Jonathan argued that the re-mapping really is an orthogonal issue that does not conceptually belong into a qdisc, a valid points as by now everyone agrees…

Best Regards
        Sebastian

> 
> -Toke