[Cerowrt-devel] [Bloat] heisenbug: dslreports 16 flow test vs cablemodems

Simon Barber simon at superduper.net
Mon May 18 11:32:44 EDT 2015

LEDBAT is often used for scavenger traffic - things that should not detract 
from normal Internet use. There are two effects, latency and bandwidth. 
While AQM solves the latency problem, it removes the ability of LEDBAT to 
not impact bandwidth during peak usage.


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On May 18, 2015 8:09:39 AM dpreed at reed.com wrote:

> I'm curious as to why one would need low priority class if you were using 
> fq_codel?  Are the LEDBAT flows indistinguishable?  Is there no congestion 
> signalling (no drops, no ECN)? The main reason I ask is that end-to-end 
> flows should share capacity well enough without magical and rarely 
> implemented things like diffserv and intserv.
> On Monday, May 18, 2015 8:30am, "Simon Barber" <simon at superduper.net> said:
> I am likely out of date about Windows Update, but there's many other 
> programs that do background downloads or uploads that don't implement 
> LEDBAT or similar protection. The current AQM recommendation draft in the 
> IETF will make things worse, by not drawing attention to the fact that 
> implementing AQM without implementing a low priority traffic class (such as 
> DSCP 8 - CS1) will prevent solutions like LEDBAT from working, or there 
> being any alternative. Would appreciate support on the AQM list in the 
> importance of this.
> Simon
> Sent with AquaMail for Android
> [ http://www.aqua-mail.com ]( http://www.aqua-mail.com )
> On May 18, 2015 4:42:43 AM "Eggert, Lars" <lars at netapp.com> wrote:On 
> 2015-5-18, at 07:06, Simon Barber <[ simon at superduper.net ]( 
> mailto:simon at superduper.net )> wrote:
> Windows update will kill your Skype call.
> Really? AFAIK Windows Update has been using a LEDBAT-like scavenger-type 
> congestion control algorithm for years now.
> Lars
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