Re: [aqm] Is bufferbloat a real problem?

Curtis Villamizar <curtis@ipv6.occnc.com> Sun, 01 March 2015 01:52 UTC

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From: Curtis Villamizar <curtis@ipv6.occnc.com>
In-reply-to: Your message of "Fri, 27 Feb 2015 21:45:19 -0500." <54F12BBF.4050503@rogers.com>
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Date: Sat, 28 Feb 2015 20:52:26 -0500
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Cc: KK <kk@cs.ucr.edu>, aqm@ietf.org
Subject: Re: [aqm] Is bufferbloat a real problem?
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In message <54F12BBF.4050503@rogers.com>
David Collier-Brown writes:
 
> Yup!
>  
> Loss is a bit of like hitting someone with  a 2 x 4" as a clue-stick. It 
> hurts, but it sure does work!
>  
> --dave

ECN might be a touch gentler.  But loss on the order of 10^-4 or less
doesn't hurt too bad.

With classsic TCP (ie: newreno or older and anything newer but not
hyper-aggresive) the estimates of the amount of loss per D*BW product
done by Matt Mathis still hold.  Now if I could just remember what
that estimate was ... in any case you get to extremely tiny loss with
anything over a few Mb/s and it goes up with square of D*BW.

Hyper-aggresive TCP (ie: CUBIC) need to be hit a lot harder.  This is
where FQ/SFQ really comes in handy.

Curtis


> On 02/27/2015 09:16 PM, KK wrote:
> > This could also be done by not having to depend on "loss" as the primary
> > source of feedback...
>  
> On 2/27/15, 6:00 PM, "David Collier-Brown" <davec-b@rogers.com> wrote:
>  
> > IMHO, removing latency is the aim of FQ. Once done, buffer sizes can be
> > unbounded (save by price (;-))