From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964947AbWDGUim (ORCPT ); Fri, 7 Apr 2006 16:38:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964944AbWDGUim (ORCPT ); Fri, 7 Apr 2006 16:38:42 -0400 Received: from [166.70.100.114] ([166.70.100.114]:57002 "EHLO mail.middle.net") by vger.kernel.org with ESMTP id S964942AbWDGUil (ORCPT ); Fri, 7 Apr 2006 16:38:41 -0400 Message-ID: <4436CDD2.7010303@middle.net> Date: Fri, 07 Apr 2006 14:38:42 -0600 From: Mark Butler User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: David Daney CC: hadi@cyberus.ca, Janos Farkas , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, pgf@foxharp.boston.ma.us, freek@macfreek.nl Subject: Re: Broadcast ARP packets on link local addresses (Version2). References: <17460.13568.175877.44476@dl2.hq2.avtrex.com> <44353F36.9070404@avtrex.com> <1144416638.5082.33.camel@jzny2> <443690C9.5090500@avtrex.com> In-Reply-To: <443690C9.5090500@avtrex.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 67.137.150.193 X-SA-Exim-Mail-From: butlerm@middle.net Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org David Daney wrote: > Following your logic through, It seems that you are advocating > broadcasting *all* ARP packets on *all* link local addresses. That > would mean that on a 192.168.* switched Ethernet network with DHCP > that twice as many ARP packets would be broadcast. 192.168.* addresses are not considered "link local", they are rather "private" or "site local" addresses. > The scope parameter, as far as I can tell, is used to make routing > decisions. Overloading it to also implement the RFC 3927 ARP > broadcasting requirement would result in generation of unnecessary > network traffic in configurations that are probably the majority of > Linux deployments. No extra network traffic, but there is some measurable overhead to looking up the scope in the routing table. One problem is having this type of scheme behave properly by default, i.e. in the absence of user specified entries. Having to create an entry for every interface in the system just to get RFC standard behavior is silly. - Mark