From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-31-ewr.dyndns.com (mxout-093-ewr.mailhop.org [216.146.33.93]) by lists.bufferbloat.net (Postfix) with ESMTP id E009F2E0077 for ; Fri, 11 Feb 2011 08:54:07 -0800 (PST) Received: from scan-32-ewr.mailhop.org (scan-32-ewr.local [10.0.141.238]) by mail-31-ewr.dyndns.com (Postfix) with ESMTP id 84F346FE3E0 for ; Fri, 11 Feb 2011 16:54:06 +0000 (UTC) X-Spam-Score: 0.0 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 76.96.62.16 Received: from qmta01.westchester.pa.mail.comcast.net (qmta01.westchester.pa.mail.comcast.net [76.96.62.16]) by mail-31-ewr.dyndns.com (Postfix) with ESMTP id 334E56FE39B for ; Fri, 11 Feb 2011 16:54:02 +0000 (UTC) Received: from omta23.westchester.pa.mail.comcast.net ([76.96.62.74]) by qmta01.westchester.pa.mail.comcast.net with comcast id 6gbF1g00N1c6gX851gu33v; Fri, 11 Feb 2011 16:54:03 +0000 Received: from [192.168.1.119] ([98.229.99.32]) by omta23.westchester.pa.mail.comcast.net with comcast id 6gu01g00K0hvpMe3jgu2iH; Fri, 11 Feb 2011 16:54:02 +0000 Message-ID: <4D5569A7.70204@freedesktop.org> Date: Fri, 11 Feb 2011 11:53:59 -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: bloat@lists.bufferbloat.net References: <1297441797.29639.8.camel@amd.pacdat.net> In-Reply-To: <1297441797.29639.8.camel@amd.pacdat.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Bloat] Failure to convince 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: Fri, 11 Feb 2011 16:54:08 -0000 On 02/11/2011 11:29 AM, richard wrote: > I had an email exchange yesterday with the top routing person at a local > ISP yesterday. Unlike my exchanges with non-tech people, this one ended > with him saying Bufferbloat was not a problem because... > > "I for for one never want to see packet loss. I spent several years > working on a national US IP network, and it was nothing but complaints > from customers about 1% packet loss between two points. Network > engineers hate packet loss, because it generates so many complaints. > And packet loss punishes TCP more than deep buffers. > > So I'm sure that you can find a bunch of network engineers who think > big buffers are bad. But the trend in network equipment in 2010 and > 2011 has been even deeper buffers. Vendors starting shipping data > centre switches with over 700MB of buffer space. Large buffers are > needed to flatten out microbursts. But these are also intelligent > buffers." > > His point about network people hating packet loss points up the problem > we'll have with educating them and the purchasing public that at least > some is necessary for TCP to function. > > Not having been in charge of a major backbone recently, I have to admit > that my understanding of today's switching hardware was to be able to > deal with everything "at wire speed" with cut-through switching, unlike > the store-and-forward typical switches and routers at the consumer > level. One response is that huge buffers actually induce higher packet loss rates on large transfers, when saturated. A happy TCP has much less than 1% loss rates. Also note that it isn't buffering per se' that is the problem here; it's unmanaged bloated buffers without signalling the hosts o fcongestion. And yes, it's an education problem, and why I'm hopeful ECN can play a role in the equation. - Jim