From owner-freebsd-questions@FreeBSD.ORG Thu May 24 20:12:26 2007 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id DF8CD16A46B for ; Thu, 24 May 2007 20:12:26 +0000 (UTC) (envelope-from af300wsm@gmail.com) Received: from py-out-1112.google.com (py-out-1112.google.com [64.233.166.181]) by mx1.freebsd.org (Postfix) with ESMTP id 8BDEC13C45D for ; Thu, 24 May 2007 20:12:26 +0000 (UTC) (envelope-from af300wsm@gmail.com) Received: by py-out-1112.google.com with SMTP id a29so1064176pyi for ; Thu, 24 May 2007 13:12:26 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=KwVqgSMPyBtWISDsLzC4T+1vvgVIeo4qxjq1uMssprq0VNeh51DKMwZkuWAfqRm8PA6X5BvTe9Zc78CE2dlWpKTXsvGq4lY+bj19JKmvaLC3Tx4MMtBFJlxaZ+TkezRwOxHrj9TikRSPuZ48GNAxoAS4Me9QT6g+TdjYsQlXDrY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=hC+Xp5axO63zeVsHYEjUCvEwyPolOrti/4KlY82DGY+2WTERRqvFE5ODdB/3Ed7fIi0aTpz8mKDhutnoP0EKG2y+jMNUOL4vbag6RVOLm1ZDCdAQoKM7bI2c3MNUdYL/ctaOUUFgzCYAbaqtuqH8Q4AXZYYLBhxA84YwvvuKTKM= Received: by 10.35.89.10 with SMTP id r10mr846581pyl.1180037545963; Thu, 24 May 2007 13:12:25 -0700 (PDT) Received: by 10.35.36.17 with HTTP; Thu, 24 May 2007 13:12:25 -0700 (PDT) Message-ID: <340a29540705241312s1eeae222u626fce3b025c7eaf@mail.gmail.com> Date: Thu, 24 May 2007 14:12:25 -0600 From: "Andrew Falanga" To: "Andrew Falanga" , freebsd-questions In-Reply-To: <20070524193327.GA58657@owl.midgard.homeip.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <340a29540705241210qa6895bem9d4aa1a5d2dd05a0@mail.gmail.com> <20070524193327.GA58657@owl.midgard.homeip.net> Cc: Subject: Re: How does FreeBSD handle tcp checksum offloading X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 24 May 2007 20:12:27 -0000 On 5/24/07, Erik Trulsson wrote: > > Checksum offloading is usually enabled by default for hardware that supports > it (assuming that the driver for that hardware also supports it of course.) > > To see if a particular interface uses checksum offloading you can look at > the output of 'ifconfig -m'. > The "options" line in the output refers to those features that are enabled, > while the "capabilities" line refers to those features that are available. > (Checksum offloading for receive and transmit show up as RXCSUM and TXCSUM > respectively.) > Ifconfig can also be used to enable/disable the offloading - see the > ifconfig(8) manpage for details and syntax. > > It can sometimes be desirable to turn of checksum offloading if one suspects > that the hardware has some bugs in it that can cause the checksum to be > wrong. (For those cases were the hardware has known bugs in this area, the > driver normally disable checksum offloading by default.) > > > Most hardware supported by the fxp(4) driver do not have support for > checksum offloading, but some do. > (The fairly commonly used 82559 chip does not support checksum while the > less common 82550 chip does, for example.) > > > Thanks for the info. This is cool. My Intel NIC is the 82550. That explains a few things. Thanks again for the info on how these are used FreeBSD. Andy