From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [NOT VERY SAFE] [TCP]: Set initial_ssthresh default to zero in Cubic and BIC. Date: Mon, 15 Oct 2007 08:55:41 -0700 Message-ID: <20071015085541.48ec63ae@freepuppy.rosehill> References: <20071006132601.f944f461.komurojun@nifty.com> <20071014073658.d4352b8c.komurojun@nifty.com> <20071014100245.914b784a.komurojun@nifty.com> <20071014132851.8d6a9de3.komurojun@nifty.com> <20071014135356.19754635.komurojun-mbn@nifty.com> <20071015215949.50399c00.komurojun-mbn@nifty.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: shemminger@linux.foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Komuro Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:51221 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752714AbXJOPzy (ORCPT ); Mon, 15 Oct 2007 11:55:54 -0400 In-Reply-To: <20071015215949.50399c00.komurojun-mbn@nifty.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, 15 Oct 2007 21:59:49 +0900 Komuro wrote: > Dear shemminger > > >In which case it is zero because that is the default value. > > The default value of snd_ssthresh is 0x7fffffff, isn't it? > > [linux/net/ipv4/tcp_ipv4.c] > static int tcp_v4_init_sock(struct sock *sk) > ... > tp->snd_ssthresh = 0x7fffffff; /* Infinity */ > ... > > Best Regards > Komuro > > Yes that value means that TCP stays in slow start until the first loss. This makes TCP behave as expected in the RFC's. -- Stephen Hemminger