[Bloat] number of home routers with ingress AQM

Sebastian Moeller moeller0 at gmx.de
Tue Apr 2 09:34:58 EDT 2019



> On Apr 2, 2019, at 15:15, Ryan Mounce <ryan at mounce.com.au> wrote:
> 
> On Tue, 2 Apr 2019 at 22:08, Sebastian Moeller <moeller0 at gmx.de> wrote:
>> 
>> I just wondered if anybody has any reasonable estimate how many end-users actually employ fair-queueing AQMs with active ECN-marking for ingress traffic @home? I am trying to understand whether L4S approach to simply declare these as insignificant in number is justifiable?
> 
> L4S people are concerned by RFC 3168 / "classic" ECN bottlenecks
> *without* fq.

	I know, but I believe that they misunderstand the issues resulting from post-bottleneck shaping, like ingress shaping on the remote side of the true bottleneck. The idea seems that sending at too high a rate is unproblematic if the AQM can simply queue up these packets and delay them accordingly. But in the ingress shaper case these packets already traversed the bottleneck and aone has payed the bandwidth price to hoist them to the home, delaying or even dropping on the AQM side will not magically get the time back the packets took traversing the link.
	Why do I care, because that ingress shaping setup is what I use at home, and I have zero confidence that ISPs will come up with a solution to my latency desires that I am going to be happy with... And what I see from the L4S mixes light with a lot of shadows.


> I don't think there would be any such ingress shapers
> configured on home gateways. Certainly not by anyone on this list...
> anyone running non-fq codel or flowblind cake for ingress shaping?

	As stated above, I believe fq to not be a reliable safety valve for the ingress shaping case.

Best Regards
	Sebastian

> 
> -Ryan




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