From owner-freebsd-stable@FreeBSD.ORG Tue Feb 13 13:17:33 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 7186C16A400 for ; Tue, 13 Feb 2007 13:17:33 +0000 (UTC) (envelope-from bms@FreeBSD.org) Received: from out4.smtp.messagingengine.com (out4.smtp.messagingengine.com [66.111.4.28]) by mx1.freebsd.org (Postfix) with ESMTP id 11AAB13C4AC for ; Tue, 13 Feb 2007 13:17:27 +0000 (UTC) (envelope-from bms@FreeBSD.org) Received: from out1.internal (unknown [10.202.2.149]) by out1.messagingengine.com (Postfix) with ESMTP id C4A5D1AEDFB; Tue, 13 Feb 2007 08:17:23 -0500 (EST) Received: from heartbeat2.messagingengine.com ([10.202.2.161]) by out1.internal (MEProxy); Tue, 13 Feb 2007 08:17:23 -0500 X-Sasl-enc: Le/PUxz0C1B1T1ZmX+evHYfHaIhkqR9ZnV3GwKoWxqXf 1171372643 Received: from [192.168.123.18] (82-35-112-254.cable.ubr07.dals.blueyonder.co.uk [82.35.112.254]) by mail.messagingengine.com (Postfix) with ESMTP id 8E9181161C; Tue, 13 Feb 2007 08:17:20 -0500 (EST) Message-ID: <45D1BA5F.2030706@FreeBSD.org> Date: Tue, 13 Feb 2007 13:17:19 +0000 From: "Bruce M. Simpson" User-Agent: Thunderbird 1.5.0.9 (X11/20070125) MIME-Version: 1.0 To: JoaoBR References: <200702130757.l1D7vPnP025671@lurza.secnetix.de> <200702130653.41321.joao@matik.com.br> In-Reply-To: <200702130653.41321.joao@matik.com.br> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Kevin Way , freebsd-stable@freebsd.org, Oliver Fromme Subject: Re: Desired behaviour of "ifconfig -alias" X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Feb 2007 13:17:33 -0000 JoaoBR wrote: > > The only correct thing you say here is that all IPs are equal - and - nobody > EVER said something different. > > Aliasing does not say anything about priority of the Ip it is simply related > to the time the interface was set with the IP so the first IP is the one > which was set first and the first alias is the one which was set after. > > The thing is, source selection policy and IP address scope blow the assumptions in this discussion out of the water, as does the concept of unnumbered IP interfaces. Scoping and selection policy is necessary to support link-local IPv4 (Zeroconf) and IPv6 as we move swiftly into a world where these things are a fact of life, and make deployment of useful IP networks for non computer users a reality. Interface preference is desirable in a stack supporting multipathing. Unnumbered IP, for example, is not dealt with at all well by the BSD stack. There are situations in which it is perfectly valid; a newly booting machine; a router at the end of a PPP link. We deal with something like 30% of the problem space for unnumbered IP. We need to be able to tell the IP stack 'be attached to this interface without a configured IP'. ifconfig syntax currently doesn't capture this requirement; the keywords 'add/delete' are closer to this intent. In the meantime, attachment of an address family to an ifnet in the kernel depends upon having at least one address configured, therefore 'alias/-alias' is the best fit to the current reality of the code. I look forward to seeing patches as a result of this discussion if anybody actually wishes to change anything. Regards, BMS