From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-13-iad.dyndns.com (mxout-081-iad.mailhop.org [216.146.32.81]) by lists.bufferbloat.net (Postfix) with ESMTP id AF9952E0601 for ; Fri, 11 Mar 2011 05:22:17 -0800 (PST) Received: from scan-11-iad.mailhop.org (scan-11-iad.local [10.150.0.208]) by mail-13-iad.dyndns.com (Postfix) with ESMTP id 144DBBDD765 for ; Fri, 11 Mar 2011 13:22:17 +0000 (UTC) X-Spam-Score: -1.0 (-) X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 194.25.30.7 Received: from tcmail33.telekom.de (tcmail33.telekom.de [194.25.30.7]) by mail-13-iad.dyndns.com (Postfix) with ESMTP id B0AA9BDD711 for ; Fri, 11 Mar 2011 13:22:15 +0000 (UTC) Received: from he111630.emea1.cds.t-internal.com ([10.134.93.22]) by tcmail31.telekom.de with ESMTP/TLS/AES128-SHA; 11 Mar 2011 14:22:13 +0100 Received: from HE111648.emea1.cds.t-internal.com ([169.254.5.253]) by HE111630.emea1.cds.t-internal.com ([::1]) with mapi; Fri, 11 Mar 2011 14:22:13 +0100 From: To: Date: Fri, 11 Mar 2011 14:22:12 +0100 Thread-Topic: some market observations Thread-Index: Acvf71SWxFVAC70zRfiUuEqhUpbkAQ== Message-ID: <580BEA5E3B99744AB1F5BFF5E9A3C67D016E72AA15@HE111648.emea1.cds.t-internal.com> Accept-Language: en-US, de-DE Content-Language: de-DE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, de-DE Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: [Bloat] some market observations 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 Mar 2011 13:22:18 -0000 interesting discussions going on here.. A consumer-oriented magazine complained that a VDSL access rated 50 mbps on= ly delivered 31 mbps. It turned out that they used a single TCP session for= their measurements. At those speeds, delay and packet loss determine the m= aximum throughput, independent of the available bandwidth. The formula in R= fC 3819, Section 8.5 yielded an estimate of ~32 mbps for the given delay an= d loss, which matched nicely the actual measurements. With increasing access bandwidths, ISPs are forced to look into the delay i= ssues. DSL bit error rates go up when everybody switches to DSL. DSL standard bodi= es look into link layer mechanisms to mitigate this, but all solutions add = delay. It's hard to find the right balance between delay and packet loss; b= oth hurt TCP performance. As delay can't be controlled by a single ISP, the= temptation is high to focus on the bit errors. Regards, Wolfgang Beck