From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-31-ewr.dyndns.com (mxout-188-ewr.mailhop.org [216.146.33.188]) by lists.bufferbloat.net (Postfix) with ESMTP id 5EB252E034F for ; Mon, 31 Jan 2011 11:16:58 -0800 (PST) Received: from scan-31-ewr.mailhop.org (scan-31-ewr.local [10.0.141.237]) by mail-31-ewr.dyndns.com (Postfix) with ESMTP id 41EFC6F7044 for ; Mon, 31 Jan 2011 19:16:56 +0000 (UTC) X-Spam-Score: 0.0 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 76.96.27.211 Received: from qmta11.emeryville.ca.mail.comcast.net (qmta11.emeryville.ca.mail.comcast.net [76.96.27.211]) by mail-31-ewr.dyndns.com (Postfix) with ESMTP id 2E4986F698E for ; Mon, 31 Jan 2011 19:16:52 +0000 (UTC) Received: from omta22.emeryville.ca.mail.comcast.net ([76.96.30.89]) by qmta11.emeryville.ca.mail.comcast.net with comcast id 2Hzm1g0041vN32cABKGrBN; Mon, 31 Jan 2011 19:16:51 +0000 Received: from [192.168.1.119] ([98.229.99.32]) by omta22.emeryville.ca.mail.comcast.net with comcast id 2KGo1g00N0hvpMe8iKGqB4; Mon, 31 Jan 2011 19:16:51 +0000 Message-ID: <4D470AA0.1020707@freedesktop.org> Date: Mon, 31 Jan 2011 14:16:48 -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: =?ISO-8859-1?Q?Dave_T=E4ht?= References: <208F592F3F104C89AA0135E5F02B2241@srichardlxp2> <20110131084108.GB29944@hydra.gt.owl.de> <4D46C44F.8000406@freedesktop.org> <87sjw9asdl.fsf@cruithne.co.teklibre.org> In-Reply-To: <87sjw9asdl.fsf@cruithne.co.teklibre.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] Bloat on Layer 2 Was: ECN & AQM Hall of Fame? 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, 31 Jan 2011 19:16:59 -0000 On 01/31/2011 12:35 PM, Dave Täht wrote: > "Richard Scheffenegger" writes: > >> BTW, I found this legacy document, where the authors boldly claim that >> more buffers are always better for 802.11 networks, to circumvent >> costly TCP congestion control decisions.... >> http://csl.snu.ac.kr/~ecpark/papers/TCP_WLAN_TMC08.pdf > > > Citing Section 3.2 > > "Effect of the Maximum Congestion Window Size on Fairness and > Utilization" > > "Based on the observation of asymmetric behavior of TCP congestion > control shown in Figs. 2 and 4, we can infer that the unfairness > problem can be alleviated by preventing packet loss from occurring. We > can avoid packet loss due to buffer overflow by either making the > buffer size, B, sufficiently large or by restricting the maximum > congestion window size, Wmax . In this section, we study the effect of > Wmax on fairness and aggregate throughput. We set B = 50 packets and > Wmax = 10..80 packets." > > I would love it if they could re-run their simulation setting "B" > according to the buffer sizes for wireless devices we are now seeing in > the field, which are in the 128..1500 packet range (not counting > retries!), under poor radio conditions. > Note that lossy wireless networks behave much better than "clean" variable bandwidth wireless networks; packet drops due to such losses at least cause TCP to back off sometimes.... - Jim