[Bloat] Bufferbloat on 4G Connexion

[Sebastian Moeller]

> On Oct 23, 2019, at 09:28, <erik.taraldsen at telenor.com> <erik.taraldsen at telenor.com> wrote:
> 
> If you could influence the 4G vendors to de-bloat their equipment, would you recommend BQL, L4S or codel/cake?

IMHO, something like BQL would be great, as would codel/cake in the devices. 
L4S however, has not been thoroughly tested and hence should be considered research-grade at best. To my knowledge none of the L4S papers/thesis so far have been performed bi-directional saturation of the network, even the PhD thesis titled Destruction Testing: Ultra-Low Delay using Dual Queue Coupled Active Queue Management).
The IMHO best set of L4S tests at https://github.com/heistp/sce-l4s-bakeoff indicates a number of "rough" edges in L4S that should be addressed before considering a roll-out
Personally I doubt that all of these can be fixed within the restraint solution space the L4S project forced upon itself (avoid flow-queueing at any cost).
So as it stands both codel and cake (and especially the fq_codel variant) have proven their usefulness in the real world, one of the big issues with both is that unless the transport interface implements some thing similar to BQL both require a computationally costly traffic shaper (cake has its own shaper built in codel/fq_codel need an additional shaper). It is not necessarily sheer number of CPU cycles, but that they seem to require low latency access to the CPU when ever deadlines approach, to try to put things to simplistically.



Best Regards
	Sebastian


> 
> 
> -Erik
> 
> 
> ________________________________________
> Fra: Bloat <bloat-bounces at lists.bufferbloat.net> på vegne av Jonathan Morton <chromatix99 at gmail.com>
> Sendt: 22. oktober 2019 23:02
> Til: Guillaume ROBIER
> Kopi: bloat at lists.bufferbloat.net
> Emne: Re: [Bloat] Bufferbloat on 4G Connexion
> 
>> On 11 Oct, 2019, at 5:56 pm, Guillaume ROBIER <grobier at icow-systems.com> wrote:
>> 
>> I am new to this mailing list and I discovered the bufferbloat in December 2018. I work on 4G routers and the bufferbloat is very present on this type of link (4G). I contact you today to find out if people have experimented with solutions on this type of link or have configuration suggestions, because the classic fq_codel or piece_of_cake and pie do not allow to fix the bufferbloat.
> 
> This is actually my own situation at home.  My solution is to insert Cake shapers on both upstream *and* downstream directions, and adjust their bandwidth settings according to variations in available 4G speed.  To do this I use an IQrouter, which is basically a TP-Link Archer C7 with custom firmware.
> 
> One of the difficulties with 4G in particular is that the link capacity varies a great deal according to both radio propagation conditions (weather, obstructions) and local usage by other subscribers.  That means the right bandwidth setting for the small hours of the night, when nobody is awake, will leave you with a lot of bloat in the evening, when everyone is both awake and home from school/work.  You will need to measure these trends and set up a bandwidth schedule accordingly.
> 
> - Jonathan Morton
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