From owner-freebsd-net@FreeBSD.ORG Fri Jan 6 18:02:17 2006 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CA4F816A420 for ; Fri, 6 Jan 2006 18:02:17 +0000 (GMT) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (gate.funkthat.com [69.17.45.168]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5DFCD43D49 for ; Fri, 6 Jan 2006 18:02:16 +0000 (GMT) (envelope-from jmg@hydrogen.funkthat.com) Received: from hydrogen.funkthat.com (localhost.funkthat.com [127.0.0.1]) by hydrogen.funkthat.com (8.13.3/8.13.3) with ESMTP id k06I288U098718; Fri, 6 Jan 2006 10:02:08 -0800 (PST) (envelope-from jmg@hydrogen.funkthat.com) Received: (from jmg@localhost) by hydrogen.funkthat.com (8.13.3/8.13.3/Submit) id k06I28hJ098717; Fri, 6 Jan 2006 10:02:08 -0800 (PST) (envelope-from jmg) Date: Fri, 6 Jan 2006 10:02:07 -0800 From: John-Mark Gurney To: kamal kc Message-ID: <20060106180207.GE69162@funkthat.com> Mail-Followup-To: kamal kc , freebsd References: <20060106071807.87771.qmail@web30008.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060106071807.87771.qmail@web30008.mail.mud.yahoo.com> User-Agent: Mutt/1.4.2.1i X-Operating-System: FreeBSD 5.4-RELEASE-p6 i386 X-PGP-Fingerprint: B7 EC EF F8 AE ED A7 31 96 7A 22 B3 D8 56 36 F4 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html Cc: freebsd Subject: Re: increasing the ethernet MTU greater than 1500 (1502) X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: John-Mark Gurney List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 06 Jan 2006 18:02:17 -0000 kamal kc wrote this message on Thu, Jan 05, 2006 at 23:18 -0800: > i tried > -->ifconfig xl1 mtu 1502 > > but it gave the message: > -->ifconfig: ioctl (set mtu): invalid argument > > How can i increase the MTU ??? > Will it have any effect whatsoever ??? > i guess ethernet should support MTU of 1502. isn't it > correct ?? Nope, for pre-gige, only 1500 MTU is supported... This was extended slightly to support vlan tagging, but I believe many of the drivers to magic behind the scenes to know when the vlan tagged packets are comming, and let them through... You could look at the drivers into fixing this.. If you have a good gige card, you can go to 9000 MTU and beyond... there is still the problem of the receiving station.. (and all switches, routers inbetween)... They must be able to support the larger MTU packet, otherwise, it coulde get dropped from the wire as too long of a packet... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."