[Cake] Getting Cake to work better with Steam and similar applications

[Jonathan Morton]

> On 29 Apr, 2017, at 18:11, Andy Furniss <adf.lists at gmail.com> wrote:
> 
> With the ingress param shaping at 1mbit 5 tcps (cubic or bbr) really
> destroys latency.
> 
> With the caveat that my test may be flawed, I am currently suspecting
> that cake cobalt head + ingress param and a low rate is buggy.

That’s odd, since I’m currently dogfooding it at 512Kbit, and it works fine like that.  Not to the point of wanting to play online games while torrenting and downloading Steam updates, but that sort of limitation comes with the territory.

With a game updater that uses *80* web-seeds simultaneously (a libtorrent quirk which should get patched in the next version), I can still reliably use my Web browser and e-mail on a second machine; these are things that start to fail intermittently over about 2 seconds RTT, and I’ve measured this ISP at 45 seconds without modification.

The key thing to remember is that in ingress mode, you *must* reduce the shaped rate to some (large) fraction of the bottleneck link, otherwise it won’t control the queue at all.  For example, I’m reasonably sure my current link is dumb-shaped to 576Kbit at the ISP.  The smaller the fraction, the better the control of latency Cake can achieve.

This is in contrast to egress mode, where you want to match the link capacity as closely as possible to get maximum performance; latency control remains ideal as long as you never actually *exceed* the true link capacity.

 - Jonathan Morton