From owner-freebsd-audit Mon Jun 25 14:56:50 2001 Delivered-To: freebsd-audit@freebsd.org Received: from netau1.alcanet.com.au (ntp.alcanet.com.au [203.62.196.27]) by hub.freebsd.org (Postfix) with ESMTP id 0E1BE37B406; Mon, 25 Jun 2001 14:56:44 -0700 (PDT) (envelope-from jeremyp@gsmx07.alcatel.com.au) Received: from mfg1.cim.alcatel.com.au (mfg1.cim.alcatel.com.au [139.188.23.1]) by netau1.alcanet.com.au (8.9.3 (PHNE_22672)/8.9.3) with ESMTP id HAA08754; Tue, 26 Jun 2001 07:56:29 +1000 (EST) Received: from gsmx07.alcatel.com.au by cim.alcatel.com.au (PMDF V5.2-32 #37641) with ESMTP id <01K57RGPE3XSVFADV7@cim.alcatel.com.au>; Tue, 26 Jun 2001 07:56:15 +1000 Received: (from jeremyp@localhost) by gsmx07.alcatel.com.au (8.11.1/8.11.1) id f5PLuOW82464; Tue, 26 Jun 2001 07:56:24 +1000 (EST envelope-from jeremyp) Content-return: prohibited Date: Tue, 26 Jun 2001 07:56:24 +1000 From: Peter Jeremy Subject: Re: Long ether frames & MTU In-reply-to: <20010625142542.Z33375@prism.flugsvamp.com>; from jlemon@flugsvamp.com on Mon, Jun 25, 2001 at 02:25:42PM -0500 To: Jonathan Lemon Cc: Yar Tikhiy , audit@FreeBSD.ORG, net@FreeBSD.ORG Mail-Followup-To: Jonathan Lemon , Yar Tikhiy , audit@FreeBSD.ORG, net@FreeBSD.ORG Message-id: <20010626075624.D95583@gsmx07.alcatel.com.au> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-disposition: inline User-Agent: Mutt/1.2.5i References: <20010625230255.A11496@comp.chem.msu.su> <20010625142542.Z33375@prism.flugsvamp.com> Sender: owner-freebsd-audit@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On 2001-Jun-25 14:25:42 -0500, Jonathan Lemon wrote: >On Mon, Jun 25, 2001 at 11:02:55PM +0400, Yar Tikhiy wrote: >> Hi there, >> >> While more and more Ethernet NIC drivers start supporting long >> frames (>1518 bytes), the user/admin still cannot raise MTU on an >> Ethernet interface above the 1500 byte limit due to outdated code >> in net/if_ethersubr.c [patch removed] >I'm not at all sure how this change will help anything, unless each >driver alters if_hdrlen. One benefit is for 802.1Q VLAN support - the existence of lots of hard-wired values that restrict frames to 1518 bytes makes configuring VLAN's a pain. It would be nice if attaching a vlan(4) to a driver that handled 1522 byte frames resulted in a 1500 byte MTU on the vlan. > Drivers which actually are able >to handle a larger mtu (e.g: 9000 byte Jumbograms) already have to do >their own checks, and thus don't call this function. IMHO, it would be nicer if more of the checking was centralised, rather than each driver repeating the same checks. Peter To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-audit" in the body of the message