[Cake] Ubiquity (Unifi ) Smart Queues

[Jonathan Morton]

> On 2 Jan, 2024, at 8:59 pm, dave seddon via Cake <cake at lists.bufferbloat.net> wrote:
> 
> 	• I'm not really sure what "overlimits" means or what that does, and tried looking this up, but I guess the kernel source is likely the "best" documentation for this.  Maybe this means it's dropping?  Or is it ECN?

Overlimit just means the shaper in HTB is restricting the flow, thus doing something useful.  Drop means the AQM is working to provide congestion information to a Not-ECT flow.  Those numbers look normal (about 0.2% drop rate, and most packets hitting "overlimit" when the link is saturated).

Using fq_codel's default parameters is not a bad thing at all.  I'd much rather they did that, thereby using numbers that are tuned for general Internet conditions, than try to change that tuning in ignorance of the end-user's actual network environment.  Most end-users have their WAN port facing "general Internet conditions" anyway.

> Apparently rather than applying the tc qdsic on the outbound path on the LAN side ( eth0 ), they are applying it inbound on the the eth2 via ifb_eth2.

That's the correct place to do it, so that the qdisc applies specifically to traffic coming from the WAN.  If you apply it to the LAN egress, it tends to affect traffic coming through the router from the WiFi or its internal servers, which is not desirable.

These are all questions we've considered at length in the process of developing and deploying Cake and other SQM solutions.

 - Jonathan Morton