From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751118AbWAYLLM (ORCPT ); Wed, 25 Jan 2006 06:11:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751119AbWAYLLL (ORCPT ); Wed, 25 Jan 2006 06:11:11 -0500 Received: from terra.ane.cmc.osaka-u.ac.jp ([133.1.74.3]:63706 "EHLO terra.ane.cmc.osaka-u.ac.jp") by vger.kernel.org with ESMTP id S1751118AbWAYLKw (ORCPT ); Wed, 25 Jan 2006 06:10:52 -0500 Message-ID: <43D75CBC.9040805@ist.osaka-u.ac.jp> Date: Wed, 25 Jan 2006 20:10:52 +0900 From: Zongsheng Zhang User-Agent: Mozilla Thunderbird 1.0.6 (Windows/20050716) X-Accept-Language: en-us, en MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: TCP fast retransmit/recovery X-Enigmail-Version: 0.93.0.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, About TCP fast retransmit/recovery, it is described in RFC 2581: 1) When the third duplicate ACK is received, set ssthresh to no more than the value max(FlightSize/2, 2*SMSS). 2) Retransmit the lost segment and set cwnd to ssthresh plus 3*SMSS. However, in kernel 2.4.31 (or 2.6.15), cwnd is always set to 1 (in tcp_enter_loss()), even there is only one packet is drop. Does anyone know the reason? Regards, -- Zongsheng Zhang zhang@ist.osaka-u.ac.jp