Re: [iccrg] [tsvwg] SCReAM (RFC8298) with CoDel-ECN and L4S

[Sebastian Moeller <[e-mail]>]

Hi Ingemar,

thanks for posting this interesting piece of data!

> On Mar 10, 2020, at 09:02, Ingemar Johansson S <ingemar.s.johansson=[e-mail]> wrote:
> 
> Hi
>  
> I recently updated the readme on the SCReAM github with a comparison with SCReAM in three different settings
> 	• No ECN
> 	• CoDel ECN
> 	• L4S
> https://github.com/EricssonResearch/scream#ecn-explicit-congestion-notification
>  
> Even though it is more than a magnitude difference in queue delay between CoDel-ECN and L4S,


	[SM] So, in this simulations of a 20ms path, SCReAM over L4S gives ~10 times less queueing delay, but also only ~2 less bandwidth compared to SCReAM over codel. You describe this as "L4S reduces the delay considerably more" and "L4S gives a somewhat lower media rate". I wonder how many end-users would tradeoff these 25ms in queueing delay against the decrease in video quality from halving the bitrate?
Could you repeat the Codel test with interval set to 20 and target to 1ms, please? 

If that improves things considerably it would argue for embedding the current best RTT estimate into SCReAM packets, so an AQM could tailor its signaling better to individual flow properties (and yes, that will require a flow-aware AQM).



> it is fair to say that these simple simulations should of course be seen as just a snapshot. 

	[SM] Fair enough.

> We hope to present some more simulations with 5G access, and not just simple bottlenecks with one flow, after the summer. 

	[Looking] forward to that.

>  
> Meanwhile, the SCReAM code on github is freely available for anyone who wish to make more experiments.
>  
> /Ingemar
> ================================
> Ingemar Johansson  M.Sc. 
> Master Researcher
>  
> Ericsson Research
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