From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-23-ewr.dyndns.com (mxout-099-ewr.mailhop.org [216.146.33.99]) by lists.bufferbloat.net (Postfix) with ESMTP id 9DD602E04AE for ; Mon, 18 Apr 2011 09:43:55 -0700 (PDT) Received: from scan-22-ewr.mailhop.org (scan-22-ewr.local [10.0.141.244]) by mail-23-ewr.dyndns.com (Postfix) with ESMTP id D11DF40248 for ; Mon, 18 Apr 2011 16:43:52 +0000 (UTC) X-Spam-Score: 0.0 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 66.111.4.28 Received: from out4.smtp.messagingengine.com (out4.smtp.messagingengine.com [66.111.4.28]) by mail-23-ewr.dyndns.com (Postfix) with ESMTP id 7EB583FB41 for ; Mon, 18 Apr 2011 16:43:48 +0000 (UTC) Received: from compute1.internal (compute1.nyi.mail.srv.osa [10.202.2.41]) by gateway1.messagingengine.com (Postfix) with ESMTP id 35F9020601 for ; Mon, 18 Apr 2011 12:43:48 -0400 (EDT) Received: from web1.messagingengine.com ([10.202.2.211]) by compute1.internal (MEProxy); Mon, 18 Apr 2011 12:43:48 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=messagingengine.com; h=message-id:from:to:mime-version:content-transfer-encoding:content-type:references:subject:in-reply-to:date; s=smtpout; bh=1onVTvdvX9V545yZ4rE6EPryYzc=; b=FhPvNRkIrpvO7b5A3L6wRRngJpzkZe08ndx6KsPwUR2mSKz26XWBj5uZwrXDAi6CrC2wD8ltqjcY/BFPVFSu8g8E1ZHMwqn5v4R1LyMD1jd3R+gm7TPI3JeVzYkFpldwSN5/NLbkcZl1dVmvSNkeJVn1C7sbQcvK0rFCiBjQt90= Received: by web1.messagingengine.com (Postfix, from userid 99) id 1720DA810E5; Mon, 18 Apr 2011 12:43:48 -0400 (EDT) Message-Id: <1303145028.24248.1442482225@webmail.messagingengine.com> X-Sasl-Enc: +qfPMhd0HHFs3exUK8RRLPrHSs60UR2GuDNF16eCV0iR 1303145028 From: "Henrique de Moraes Holschuh" To: "Bufferbloat Mainlinglist" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" X-Mailer: MessagingEngine.com Webmail Interface References: <4DA67BBE.9050606@taht.net> In-Reply-To: <4DA67BBE.9050606@taht.net> Date: Mon, 18 Apr 2011 13:43:48 -0300 Subject: [Bloat] tcp_ecn=2 (server-mode ECN) X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Apr 2011 16:43:55 -0000 On Wed, 13 Apr 2011 22:44 -0600, "Dave Taht" wrote: > He'd not noticed the problem because ubuntu 10.4 (at least, he also > runs bsd) has tcp_ecn=2, which so far as I know "tries" a ECN enabled > connect then falls back to not using it. tcp_ecn=2 is "server mode ECN". It will enable ECN if, and ONLY if, the other side requests it during the initial TCP handshake. AFAICT, it effectively disables ECN on all outgoing connections and enables it on incoming connections should the other host request ECN (which it won't when it is also running in tcp_ecn=2 mode). It is also the kernel default, and AFAIK, the default on every 2010+ Linux distro stable releases. If you want to use ECN, you have to set tcp_ecn=1 in your Linux box when you're the one originating TCP connections. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh