From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-33-ewr.dyndns.com (mxout-181-ewr.mailhop.org [216.146.33.181]) by lists.bufferbloat.net (Postfix) with ESMTP id BB7562E0182 for ; Mon, 7 Feb 2011 11:57:02 -0800 (PST) Received: from scan-31-ewr.mailhop.org (scan-31-ewr.local [10.0.141.237]) by mail-33-ewr.dyndns.com (Postfix) with ESMTP id E36356FA3A2 for ; Mon, 7 Feb 2011 19:56:58 +0000 (UTC) X-Spam-Score: 0.0 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 76.96.59.212 Received: from qmta14.westchester.pa.mail.comcast.net (qmta14.westchester.pa.mail.comcast.net [76.96.59.212]) by mail-33-ewr.dyndns.com (Postfix) with ESMTP id 7FA326FA52B for ; Mon, 7 Feb 2011 19:56:52 +0000 (UTC) Received: from omta08.westchester.pa.mail.comcast.net ([76.96.62.12]) by qmta14.westchester.pa.mail.comcast.net with comcast id 57w81g0070Fqzac5E7wtaE; Mon, 07 Feb 2011 19:56:53 +0000 Received: from [192.168.1.119] ([98.229.99.32]) by omta08.westchester.pa.mail.comcast.net with comcast id 57wo1g01o0hvpMe3U7woCv; Mon, 07 Feb 2011 19:56:53 +0000 Message-ID: <4D504E7F.6030602@freedesktop.org> Date: Mon, 07 Feb 2011 14:56:47 -0500 From: Jim Gettys Organization: Bell Labs User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101208 Lightning/1.0b2 Thunderbird/3.1.7 MIME-Version: 1.0 To: esr@thyrsus.com References: <20110206143952.AC0CF20C22E@snark.thyrsus.com> <4D4EC2D4.2070708@freedesktop.org> <20110206202015.GA3004@thyrsus.com> In-Reply-To: <20110206202015.GA3004@thyrsus.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Eric Raymond , bloat@lists.bufferbloat.net Subject: Re: [Bloat] Overview modifications 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, 07 Feb 2011 19:57:04 -0000 On 02/06/2011 03:20 PM, Eric Raymond wrote: > Jim Gettys: >>> Change in progress -- append to the "Hating" paragraph the following >>> sentence: "Lossy networks such as wireless actually show less chaotic >>> behavior under load than clean ones." Is this correct and adequate? >> >> It's not chaotic behaviour. In fact, it is much more worrying: it >> is periodic (oscillatory) behaviour. Chaos is good, in this case. > > Dave also says my take is wrong and is promising to suggest a correction. > I have enough other stuff to do that I'll wait on that. > >> My nightmare, is that as traffic shifts over more and more to >> saturated links as XP retires, we end up with self synchronising >> behaviour on a local, regional or global scale, and havoc ensues, >> and parts/all of the Internet stop working. Whether these fears are >> justified, I do not know. >> >> Think: we may be a column of soldiers in cadence approaching a bridge... > > New graphs at the end of "From Highway to Network": > > We also have some worries about the future. For various reasons > (including the gradual retirement of Windows XP) more and more > Internet traffic is now running over saturated links. In this new > environment, we think there is a possibility that bufferbloat cascades > and defects in management strategies might produce self-synchronising > behaviour in network traffic - packet floods and network resonance on > a local, regional or global scale that could be a greater threat to > the Internet than the congestion-driven near-collapse of the NSF > backbone in 1986. It's not just bufferbloat: a number of network technologies are bunching up packets and injecting them into the Internet with periodic bursts. Unfortunately, I don't have good references to this; I gather this is true of both wireless and wired technologies. > > This is a classic "black swan" situation in Nassim Taleb's sense; in > today's Internet-dependent economy there is a potential for nearly > inacalculable havoc in the worst case, but we don't even know in > principle how to estimate the overall risk. Bufferbloat mitigation > might keep us out of some very serious trouble, and is worth pursuing > on those grounds alone. It's actually a general fear of any periodic behaviour; I'm just spooked to see it in such long period TCP traffic. Van warned me about time based congestion phenomena in general.