From owner-freebsd-hackers Tue May 29 18:52:19 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from mailsrv.otenet.gr (mailsrv.otenet.gr [195.170.0.5]) by hub.freebsd.org (Postfix) with ESMTP id D8FE637B423 for ; Tue, 29 May 2001 18:52:14 -0700 (PDT) (envelope-from keramidi@otenet.gr) Received: from hades.hell.gr (patr530-b052.otenet.gr [195.167.121.180]) by mailsrv.otenet.gr (8.11.1/8.11.1) with ESMTP id f4U1q5e29870; Wed, 30 May 2001 04:52:05 +0300 (EEST) Received: (from charon@localhost) by hades.hell.gr (8.11.3/8.11.3) id f4U1q1401187; Wed, 30 May 2001 04:52:01 +0300 (EEST) (envelope-from keramidi@otenet.gr) Date: Wed, 30 May 2001 04:52:00 +0300 From: Giorgos Keramidas To: Bob Willcox Cc: Jesper Skriver , hackers list Subject: Re: How to disable software TCP checksumming? Message-ID: <20010530045200.A1031@hades.hell.gr> References: <20010529144114.I19771@luke.immure.com> <20010529221107.C49875@skriver.dk> <20010529155212.M19771@luke.immure.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20010529155212.M19771@luke.immure.com>; from bob@immure.com on Tue, May 29, 2001 at 03:52:12PM -0500 X-PGP-Fingerprint: 3A 75 52 EB F1 58 56 0D - C5 B8 21 B6 1B 5E 4A C2 X-URL: http://students.ceid.upatras.gr/~keramida/index.html Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Tue, May 29, 2001 at 03:52:12PM -0500, Bob Willcox wrote: | | and may prevent the upper layers from checking the CRC on input. There are good reasons why checksumming in upper layers should not be disabled even if some lower layer does checksumming of its own. I recall reading some good points on this one at "TCP/IP Illustrated, Volume I" from (now late) Richard W. Stevens. In fact, this is exactly what the sysctl knob net.inet.udp.checksum is there for. The knob having a default value of 1 (checksumming enabled), means that checksumming is used. If you do change checksumming in TCP, please provide a similar knob for that protocol, and have it set to a default of 1 (still enabled). This way if someone feels comfortable to have checksums disabled in TCP, or some higher layer, they can still do it, but the default behavior is the good ole' FreeBSD we all know and love. --giorgos To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message