From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 1497D2022BC for ; Sun, 24 Jun 2012 22:29:32 -0700 (PDT) Received: by wibhn14 with SMTP id hn14so2086863wib.10 for ; Sun, 24 Jun 2012 22:29:31 -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=qWw2fL28BHicgtZHmwMx2wN8qu/2TWFQUJ2xat5/uYo=; b=PFGJNrcVnpqXJ6TEFoGBZCcufzABRqEGu/R6ENOrdkHjs4w6zHW2vLHmfjc2Y2y48o nkbz1JXgyCb05y1K7Pz/zUnE7ZDbrDvHuJqgbCv9xYyaAJ8LOuJj1ThfxB9Fdy/n67d5 cV3DItUBKu2fZl8ApM72PYX25ryQUrVuRWZ8Rd73d4XnIFxCvDZcxQLveOO8Oml1ivCQ TiMOTMaXp0cA7fpXqdApTWX4eHaY84/+1ObZlb/DwK1h1cwEvUYIt+gLGBdYQD7K2TmM 3MTOL/NmHSZGTrKOOff32VsSfpRwNlE53DE9VwcG707NiTgGhZDUzbfSRcPLeQP2PkSG XUXg== Received: by 10.216.143.147 with SMTP id l19mr5870148wej.59.1340602170905; Sun, 24 Jun 2012 22:29:30 -0700 (PDT) Received: from [192.168.1.37] (122.237.66.86.rev.sfr.net. [86.66.237.122]) by mx.google.com with ESMTPS id d10sm30208795wiy.3.2012.06.24.22.29.29 (version=SSLv3 cipher=OTHER); Sun, 24 Jun 2012 22:29:30 -0700 (PDT) From: Eric Dumazet To: Dave =?ISO-8859-1?Q?T=E4ht?= In-Reply-To: <1340600422-1806-1-git-send-email-dave.taht@bufferbloat.net> References: <1340600422-1806-1-git-send-email-dave.taht@bufferbloat.net> Content-Type: text/plain; charset="UTF-8" Date: Mon, 25 Jun 2012 07:29:28 +0200 Message-ID: <1340602168.23933.22.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 8bit Cc: codel@lists.bufferbloat.net Subject: Re: [Codel] [RFCv2 PATCH] iproute2: Add ecn_target option to codel and fq_codel X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 25 Jun 2012 05:29:33 -0000 On Sun, 2012-06-24 at 22:00 -0700, Dave Täht wrote: > From: Dave Taht > > ECN was not part of the original codel design and adding support > for it revealed problems in two areas. 1) ECN can be gamed. > 2) Dropping packets under overload more rapidly frees up > bandwidth than marking packets. > > Two possible scenarios of use - on egress from a network, > ecn_target could be set low, to drop more often, to > ensure lowest latency for other packets. > > On ingress, it could be set high to mark packets more often, > to lower data loss while still signalling the end application > that bandwidth is a problem. > > ecn_target is not engaged until after codel enters a dropping > state overall. I would suggest 'drop_above' instead of ecn_target, since its quite different than the 'target' (And dont display/output it if ecn is not set, no need to confuse users who didn't enable ecn on CoDel)