From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S272444AbTHSRUB (ORCPT ); Tue, 19 Aug 2003 13:20:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S272417AbTHSRTr (ORCPT ); Tue, 19 Aug 2003 13:19:47 -0400 Received: from pizda.ninka.net ([216.101.162.242]:34699 "EHLO pizda.ninka.net") by vger.kernel.org with ESMTP id S272052AbTHSRRA (ORCPT ); Tue, 19 Aug 2003 13:17:00 -0400 Date: Tue, 19 Aug 2003 10:09:29 -0700 From: "David S. Miller" To: Stephan von Krawczynski Cc: willy@w.ods.org, richard@aspectgroup.co.uk, alan@lxorguk.ukuu.org.uk, carlosev@newipnet.com, lamont@scriptkiddie.org, davidsen@tmr.com, bloemsaa@xs4all.nl, marcelo@conectiva.com.br, netdev@oss.sgi.com, linux-net@vger.kernel.org, layes@loran.com, torvalds@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [2.4 PATCH] bugfix: ARP respond on all devices Message-Id: <20030819100929.0bfefbb4.davem@redhat.com> In-Reply-To: <20030819191246.027061dd.skraw@ithnet.com> References: <353568DCBAE06148B70767C1B1A93E625EAB58@post.pc.aspectgroup.co.uk> <20030819145403.GA3407@alpha.home.local> <20030819170751.2b92ba2e.skraw@ithnet.com> <20030819085717.56046afd.davem@redhat.com> <20030819185219.116fd259.skraw@ithnet.com> <20030819095302.7213ddd5.davem@redhat.com> <20030819191246.027061dd.skraw@ithnet.com> X-Mailer: Sylpheed version 0.9.2 (GTK+ 1.2.6; sparc-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 19 Aug 2003 19:12:46 +0200 Stephan von Krawczynski wrote: > On Tue, 19 Aug 2003 09:53:02 -0700 > "David S. Miller" wrote: > > > In the ARP request we are using the source address in the packet we > > are building for output. > > > > If ARP doesn't work using that source address, we can only assume IP > > communication is not possible either. > > > > It is the box not responding to this ARP which is preventing > > communication not the box creating the ARP request. > > Please read my example from other email. Very simple to prove you wrong here. Not really, the RFC you keep quoting is broken in several regards: 1) It is non-functional in environments containing systems using the host ownership model for IP addresses which the RFC standards fully allow. 2) It does not consider the cases where a host is not completely aware of all subnets present on a given link. This is actually quite common. Dropping such ARP requests can only be done when the the host is aware of all subnets that exist, which is cannot be possibly true.