[Cake] low bandwidth default params best effort vs voice latency.

[Andy Furniss]

Dave Taht wrote:
> One thing the original sqm-scripts did (with fq_codel) was explicitly
> deprioritize ping with a filter.
>
> I had written  in my original "wondershaper must die" rant how stupid
> it was to prioritize ping upwards  to "impress your friends" - as that
> was the case in many, many a wshaper implementation I'd seen.
>
> I only just now noticed that rant does not have the images inline.
> "Oh, man, ping's prioritized:"
>
> https://www.bufferbloat.net/projects/attachments/131229050304_wshaper-800-220.svg
>
> As for explicit depriorization, well, I took a lot of flack from some
> ietfers about lowering it below best effort, and I felt the additional
> classification needed was excessive for cake, directly. Some OSes
> already do mark it with a background class.  I still think it's a good
> idea as it makes ping floods against (for example) your entire 10.
> network (which happened to me under worm attack once) - vanish.

Yea, fair point, but in this case it's just a simulation tool as I don't
know how to get delay times from a udp stream.

I still think cs4 should go to voice on diffserv3 as it does on diffserv4.

Another observation with flent udp_flood, I notice that 
flent-london.bufferbloat.net
is tcp only, is this intended? The test still works, despite the port
unreachables coming back, just no bandwidth reading.