From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-21-ewr.dyndns.com (mxout-067-ewr.mailhop.org [216.146.33.67]) by lists.bufferbloat.net (Postfix) with ESMTP id 645672E02E9 for ; Sat, 5 Feb 2011 07:13:07 -0800 (PST) Received: from scan-21-ewr.mailhop.org (scan-21-ewr.local [10.0.141.243]) by mail-21-ewr.dyndns.com (Postfix) with ESMTP id 9F1931F20 for ; Sat, 5 Feb 2011 15:13:05 +0000 (UTC) X-Spam-Score: 0.1 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 75.145.127.229 Received: from gw.co.teklibre.org (75-145-127-229-Colorado.hfc.comcastbusiness.net [75.145.127.229]) by mail-21-ewr.dyndns.com (Postfix) with ESMTP id B121F160A for ; Sat, 5 Feb 2011 15:13:01 +0000 (UTC) Received: from cruithne.co.teklibre.org (unknown [IPv6:2002:4b91:7fe5:2:21c:25ff:fe80:46f9]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "cruithne.co.teklibre.org", Issuer "CA Cert Signing Authority" (verified OK)) by gw.co.teklibre.org (Postfix) with ESMTPS id 16D2E5E88A for ; Sat, 5 Feb 2011 08:13:01 -0700 (MST) Received: by cruithne.co.teklibre.org (Postfix, from userid 1000) id 13920121B7B; Sat, 5 Feb 2011 08:13:00 -0700 (MST) From: d@taht.net (Dave =?utf-8?Q?T=C3=A4ht?=) To: Jim Gettys Organization: Teklibre - http://www.teklibre.com References: <20110205132305.GA29396@thyrsus.com> <4D4D53BA.5020003@freedesktop.org> Date: Sat, 05 Feb 2011 08:12:59 -0700 In-Reply-To: <4D4D53BA.5020003@freedesktop.org> (Jim Gettys's message of "Sat, 05 Feb 2011 08:42:18 -0500") Message-ID: <87vd0yikg4.fsf@cruithne.co.teklibre.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] First draft of complete "Bufferbloat And You" enclosed. 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: Sat, 05 Feb 2011 15:13:08 -0000 Jim Gettys writes: > Several reactions: > [elided] > But memory is sooo cheap we've paved Texas over with extra road, just > in case. Why pick on Texas? The maximum latency yet reported was 40 seconds, which is like 31 lunar distances (40/1.28), or half that if you are measuring latency as RTT. It's one of those mind-bogglingly big numbers that douglas adams warned us about. I wouldn't be surprised if someone reported RTT times as large as between here and Venus. Texas has enough problems. > (QOS isn't universal, much less your complicated rules). Fix the > bloat: then classify. For years a very simple classification scheme has existed by default. Most UDP packets actually used the TOS field sanely and the OS would prioritize those packets appropriately. It worked, mostly. It's been devilish with SIP, however. A few other classification schemes have worked well in the field - the wondershaper started a trend to prioritize interactive ack packets, which helps interactive traffic (ssh, x11, stuff like that) a lot, improving latency under load for latency dependent tcp streams. Most of the others... Not so much. Interesting edge cases. Maybe a diamond in the rough here and there. Lastly, I make a distinction between QoS and AQM - one that's kind of hard to define. To me AQM is about trying to ensure overall fairness and goodput (techniques like RED and SFB) by managing queues sanely, and QoS is about providing high speed lanes with special properties for certain kinds of traffic. Both ARE useful, but can be addressed in order of reducing unmanaged buffers, applying AQM, and then QoS. > Many people will need to replace their routers, and will believe that > is expensive; and to them, buying a $100 router *is* > expensive. Remember your audience. And various ISP's aren't going to > like the bottom line cost of replacing/upgrading all the broken > equipment. A lot of them can just get new firmware. Although it's likely that dd-wrt and openwrt are worse, out of the box, at present. My concern is after observing several reviews of new wireless kit in the press that the most modern gear is exhibiting bufferbloat problems, as yet undiagnosed. Possibly here: http://online.wsj.com/article/SB10001424052748704774604576035691589888786.html Certainly here: http://www.dd-wrt.com/phpBB2/viewtopic.php?p=416640&sid=635145ce6d7ee3bb695b39ace6b9c101 -- Dave Taht http://nex-6.taht.net