From owner-freebsd-net@FreeBSD.ORG Sun Mar 9 09:17:25 2008 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 83EED106566C for ; Sun, 9 Mar 2008 09:17:25 +0000 (UTC) (envelope-from silby@silby.com) Received: from relay03.pair.com (relay03.pair.com [209.68.5.17]) by mx1.freebsd.org (Postfix) with SMTP id 1573F8FC14 for ; Sun, 9 Mar 2008 09:17:24 +0000 (UTC) (envelope-from silby@silby.com) Received: (qmail 71850 invoked from network); 9 Mar 2008 09:17:23 -0000 Received: from unknown (HELO localhost) (unknown) by unknown with SMTP; 9 Mar 2008 09:17:23 -0000 X-pair-Authenticated: 209.68.2.70 Date: Sun, 9 Mar 2008 04:17:22 -0500 (CDT) From: Mike Silbersack To: Jake Rizzo In-Reply-To: Message-ID: <20080309041601.X37603@odysseus.silby.com> References: <20080307185203.J27119@niwun.pair.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-net@freebsd.org Subject: Re: RELENG-7 tcp connectivity problems with certain clients X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Mar 2008 09:17:25 -0000 On Sun, 9 Mar 2008, Jake Rizzo wrote: > The patch didn't work, but doing this: > > sysctl net.inet.tcp.tso=0 > sysctl net.inet.tcp.sack.enable=0 > > Allows the client to connect again. Since my ifconfig doesn't show that my > nic supports TSO then I presume it's the sack sysctl that's making it work. > > The machine's a webserver serving almost exclusively dynamic content - with > sack disabled is it likely to affect performance much? > > Thanks, > Jake SACK makes retransmission more effective in some circumstances when packet loss occurs. So, you're probably not going to notice it being disabled at all. In fact. FreeBSD 4.x didn't have any SACK support whatsoever. -Mike