From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <eric.dumazet@gmail.com>
Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com
	[209.85.212.181]) (using TLSv1 with cipher RC4-SHA (128/128 bits))
	(Client CN "smtp.gmail.com",
	Issuer "Google Internet Authority" (verified OK))
	by huchra.bufferbloat.net (Postfix) with ESMTPS id 4006421F0DB
	for <codel@lists.bufferbloat.net>; Sat,  4 Aug 2012 22:30:29 -0700 (PDT)
Received: by wibhm2 with SMTP id hm2so530192wib.10
	for <codel@lists.bufferbloat.net>; Sat, 04 Aug 2012 22:30:27 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
	h=subject:from:to:cc:in-reply-to:references:content-type:date
	:message-id:mime-version:x-mailer:content-transfer-encoding;
	bh=0rmVPGjboWP2me5fm+kV5qBBcU0F4V0hjBgFB2iwHDc=;
	b=S3eMDWqFx/hlroN17QmGyFIpQZNhdSPUziLNDVTTKx5FGLtxOBEbJEBzuwyIuKsf4M
	6tRRHPRgbSPoKJm86OaShlr5iKRoK8VRJg3N+RHtWVmxA0BvvykFNL7IPYlO2/+NOc8K
	4PW+32SpxCwWMIvsFGX6+kVDmdq1wmT9kjpBPqsqATJq/4TZwcWEOIvYwE7mog54lLws
	0ra6vOtSb5c2BI7VnGWaX6OV3sY/+qTrVDN+RaeENzwKhklMaZE98xuXzuZ7wLEBjfR6
	wvThcSEAnuKYfd2qw/IvEQvCAUZIvJyfTaxxuCBhfMynt0a5l8iJSahRlSdtTDEVhpcU
	WDwQ==
Received: by 10.216.42.65 with SMTP id i43mr3596365web.208.1344144627524;
	Sat, 04 Aug 2012 22:30:27 -0700 (PDT)
Received: from [172.30.42.18] (171.237.66.86.rev.sfr.net. [86.66.237.171])
	by mx.google.com with ESMTPS id ef5sm11099110wib.3.2012.08.04.22.30.25
	(version=SSLv3 cipher=OTHER); Sat, 04 Aug 2012 22:30:26 -0700 (PDT)
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Andrew McGregor <andrewmcgr@gmail.com>
In-Reply-To: <7EB59257-1A8E-4567-8AD3-5016594565CC@gmail.com>
References: <1344048299-26267-1-git-send-email-dave.taht@bufferbloat.net>
	<1344062738.9299.1453.camel@edumazet-glaptop>
	<501D99C4.20902@pollere.com>
	<7EB59257-1A8E-4567-8AD3-5016594565CC@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Date: Sun, 05 Aug 2012 07:30:23 +0200
Message-ID: <1344144623.9299.1557.camel@edumazet-glaptop>
Mime-Version: 1.0
X-Mailer: Evolution 2.28.3 
Content-Transfer-Encoding: 7bit
Cc: codel@lists.bufferbloat.net
Subject: Re: [Codel] [RFC PATCH] codel: ecn mark at target
X-BeenThere: codel@lists.bufferbloat.net
X-Mailman-Version: 2.1.13
Precedence: list
List-Id: CoDel AQM discussions <codel.lists.bufferbloat.net>
List-Unsubscribe: <https://lists.bufferbloat.net/options/codel>,
	<mailto:codel-request@lists.bufferbloat.net?subject=unsubscribe>
List-Archive: <https://lists.bufferbloat.net/pipermail/codel>
List-Post: <mailto:codel@lists.bufferbloat.net>
List-Help: <mailto:codel-request@lists.bufferbloat.net?subject=help>
List-Subscribe: <https://lists.bufferbloat.net/listinfo/codel>,
	<mailto:codel-request@lists.bufferbloat.net?subject=subscribe>
X-List-Received-Date: Sun, 05 Aug 2012 05:30:31 -0000

On Sat, 2012-08-04 at 20:06 -0700, Andrew McGregor wrote:
> Well, thanks Eric for trying it.
> 
> Hmm.  How was I that wrong?  Because I was supporting that idea.
> 
> Time to think.

No problem Andrew ;)

Its seems ECN is not well enough understood.

ECN marking a packet has the same effect for the sender : reducing cwnd
exactly like a packet drop. Only difference is avoiding the
retransmit[s].

It cannot be used only to send a 'small' warning, while other competing
non ECN flows have no signal.

As far as packet schedulers are concerned, there should be no difference
in ECN marking and dropping a packet. I believe linux packet schedulers
are fine in this area.

Now, there are fundamental issues with ECN itself, out of Codel scope,
thats for sure.

How widely has been RFC 3540 deployed, anybody knows ?