From owner-freebsd-stable@FreeBSD.ORG Fri Jan 15 19:21:59 2010 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EF94B1065672 for ; Fri, 15 Jan 2010 19:21:59 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from asmtpout027.mac.com (asmtpout027.mac.com [17.148.16.102]) by mx1.freebsd.org (Postfix) with ESMTP id C30108FC1B for ; Fri, 15 Jan 2010 19:21:59 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=us-ascii Received: from cswiger1.apple.com ([17.227.140.124]) by asmtp027.mac.com (Sun Java(tm) System Messaging Server 6.3-8.01 (built Dec 16 2008; 32bit)) with ESMTPSA id <0KWA009F9Z46L630@asmtp027.mac.com> for freebsd-stable@freebsd.org; Fri, 15 Jan 2010 11:21:47 -0800 (PST) From: Chuck Swiger In-reply-to: <491716.58173.qm@web50503.mail.re2.yahoo.com> Date: Fri, 15 Jan 2010 11:21:41 -0800 Message-id: <81046D84-0BF4-4F3C-A262-B28A39F9D4A0@mac.com> References: <491716.58173.qm@web50503.mail.re2.yahoo.com> To: alan bryan X-Mailer: Apple Mail (2.1077) Cc: freebsd-stable@freebsd.org Subject: Re: General problems with checksums (txcsum/rxcsum) on FreeBSD 8.0? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Jan 2010 19:22:00 -0000 Hi-- On Jan 15, 2010, at 11:12 AM, alan bryan wrote: [ ... ] > I'm currently sifting through a tcpdump in wireshark and there are all sorts of messages in there about checksums being incorrect - both TCP and UDP. If you run tcpdump on a machine, it normally will receive the traffic being sent from that machine before the checksums are computed, especially if HW checksumming is being used. For reliable detection of these problems, you need to look at the traffic either on a hub or via the monitoring or span port of a smart switch, although simply glancing at the checksum stats from "netstat -s" on both sides should indicate whether significant error rates are happening. Regards, -- -Chuck