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Date:      Fri, 09 Jun 2000 13:14:32 -0700
From:      Peter Wemm <peter@netplex.com.au>
To:        Thierry Herbelot <herbelot@cybercable.fr>
Cc:        "Gary T. Corcoran" <gcorcoran@lucent.com>, Luigi Rizzo <luigi@info.iet.unipi.it>, net@FreeBSD.ORG
Subject:   Re: HEADS UP- WF2Q and RED now available in -current 
Message-ID:  <20000609201432.3D4DC1CE4@overcee.netplex.com.au>
In-Reply-To: Message from Thierry Herbelot <herbelot@cybercable.fr>  of "Thu, 08 Jun 2000 22:16:54 %2B0200." <393FFF36.BE411C54@cybercable.fr> 

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Thierry Herbelot wrote:
> "Gary T. Corcoran" wrote:
> > 
> > Luigi,
> > 
> > > as the subject says, i have just committed some new code to
> > > dummynet (and related hooks and documentation for ipfw) to
> > > implement RED (thanks to Gianluca Iannaccone) and a
> > > variant of Weighted Fair Queueing called WF2Q+
> > 
> > I checked your web page, but didn't find anything describing
> > what "RED" is.  And I'm afraid if I just put "red" into a
> > search engine I'll get a zillion results...  ;-)
> > 
> > So could you just very briefly explain what "RED" is, and/or
> > point me to a URL which describes it?
> 
> Random Early Discard : if the channel has not enough bandwidth, just
> throw away some frames (randomly)

More to the point, it takes advantage of TCP backoff to slow down all the
TCP sessions so that you don't quite get to the point of hitting the 100%
limit and losing a large chunk of in-flight data.  If you drop a few packets
earlier you can "shape" the tcp connection(s) so that they don't hit the
wall hard.

Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
"All of this is for nothing if we don't go to the stars" - JMS/B5



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