From owner-freebsd-net@FreeBSD.ORG Sun Jan 23 11:22:34 2005 Return-Path: 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 8419516A4CE for ; Sun, 23 Jan 2005 11:22:34 +0000 (GMT) Received: from postfix3-1.free.fr (postfix3-1.free.fr [213.228.0.44]) by mx1.FreeBSD.org (Postfix) with ESMTP id D4B4643D46 for ; Sun, 23 Jan 2005 11:22:33 +0000 (GMT) (envelope-from tataz@tataz.chchile.org) Received: from tatooine.tataz.chchile.org (vol75-8-82-233-239-98.fbx.proxad.net [82.233.239.98]) by postfix3-1.free.fr (Postfix) with ESMTP id BBABC17353B; Sun, 23 Jan 2005 12:22:30 +0100 (CET) Received: by tatooine.tataz.chchile.org (Postfix, from userid 1000) id E358A407C; Sun, 23 Jan 2005 12:22:19 +0100 (CET) Date: Sun, 23 Jan 2005 12:22:19 +0100 From: Jeremie Le Hen To: Brooks Davis Message-ID: <20050123112219.GJ36660@obiwan.tataz.chchile.org> References: <41F1E99A.5070001@ntmk.ru> <20050122152546.GG36660@obiwan.tataz.chchile.org> <20050122203347.GB4466@odin.ac.hmc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050122203347.GB4466@odin.ac.hmc.edu> User-Agent: Mutt/1.5.6i cc: freebsd-net@freebsd.org cc: Boris Kovalenko cc: Jeremie Le Hen Subject: Re: [PATCH] 802.1p priority (fixed) X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 23 Jan 2005 11:22:34 -0000 > > Having the possibility to test and set the 802.1p or TOS values > > separately would avoid making a "trust"/"override" subtlety and will > > obviously make it more flexible. > > I agree on this point. The one thing to be careful of is that 802.1p > priorities and TOS values work rather differently in that TOS values fit > in to an existing field of the packet and 802.1p values require > modifications to the header and adding data between the header and the > real body, possiably with a resuling reduction in MTU (though what > you're doing trying to use 802.1p priority with crappy nic I don't know > :-). I do not understand your point here. TOS is indeed an existing field of the IPv4 header but AFAIK, this is the same for the 802.1p header [1]. There are already 3 bits reserved for priority (802.1p) near the 802.1q field which are both inside what they call "Tag Control Information". Regards, [1] http://www.networkdictionnary.com/protocols/8021p.php -- Jeremie Le Hen jeremie@le-hen.org