From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kristian Evensen Subject: Re: Strange TCP behavior over HSDPA Date: Tue, 29 Dec 2009 10:59:43 +0100 Message-ID: <4B39D30F.8090006@gmail.com> References: <20091229083050.GA7209@ff.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Jarek Poplawski Return-path: Received: from mail-ew0-f219.google.com ([209.85.219.219]:47589 "EHLO mail-ew0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752684AbZL2KDT (ORCPT ); Tue, 29 Dec 2009 05:03:19 -0500 Received: by ewy19 with SMTP id 19so2552080ewy.21 for ; Tue, 29 Dec 2009 02:03:18 -0800 (PST) In-Reply-To: <20091229083050.GA7209@ff.dom.local> Sender: netdev-owner@vger.kernel.org List-ID: Den 29.12.2009 09:30, skrev Jarek Poplawski: > The most obvious difference seems to be the SACK option used in [2], > so maybe something on the route breaks it (without tunnels). > > Jarek P. > Thank you for your reply. I have tried disabling SACK and then the performance when packet loss occured got even worse, and the rest of the time it was pretty similar. After finally getting hold of someone I know at my ISP, I was told that they use TCP accelerators in their mobile network. Also, when looking at the packet captures from the server side I see that the sequene numbers are changed, so there is a machine doing something to the packets along the route. What I suspect is that this or these machines somehow breaks when a retransmission occurs. I am not quire sure what could cause it though, for example all dupAcks generated by the client are recieved by the server, but hopefully my ISP will be able to figure it out. -Kristian