From owner-freebsd-net@FreeBSD.ORG Thu Oct 25 10:12:07 2007 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DC82C16A418 for ; Thu, 25 Oct 2007 10:12:07 +0000 (UTC) (envelope-from bms@FreeBSD.org) Received: from out1.smtp.messagingengine.com (out1.smtp.messagingengine.com [66.111.4.25]) by mx1.freebsd.org (Postfix) with ESMTP id BF01D13C4A8 for ; Thu, 25 Oct 2007 10:12:07 +0000 (UTC) (envelope-from bms@FreeBSD.org) Received: from compute1.internal (compute1.internal [10.202.2.41]) by out1.messagingengine.com (Postfix) with ESMTP id 7D5DB344E6; Thu, 25 Oct 2007 05:52:12 -0400 (EDT) Received: from heartbeat1.messagingengine.com ([10.202.2.160]) by compute1.internal (MEProxy); Thu, 25 Oct 2007 05:52:12 -0400 X-Sasl-enc: oKuWy2uYxTmVvqqUtKcLaNGco1l1m91VN6LWF5v7B0/6 1193305932 Received: from empiric.lon.incunabulum.net (82-35-112-254.cable.ubr07.dals.blueyonder.co.uk [82.35.112.254]) by mail.messagingengine.com (Postfix) with ESMTP id E423C1AD8; Thu, 25 Oct 2007 05:52:11 -0400 (EDT) Message-ID: <4720674A.9090009@FreeBSD.org> Date: Thu, 25 Oct 2007 10:52:10 +0100 From: "Bruce M. Simpson" User-Agent: Thunderbird 2.0.0.6 (X11/20070928) MIME-Version: 1.0 To: LiuJiusheng References: <471EF736.1070207@galaxywind.com> <20071024185610.GE39759@funkthat.com> <471FF1AC.4000800@galaxywind.com> In-Reply-To: <471FF1AC.4000800@galaxywind.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-net@freebsd.org, gurney_j@resnet.uoregon.edu Subject: Re: Routing problems X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Oct 2007 10:12:07 -0000 LiuJiusheng wrote: > Linux takes 6.6.6.2 as gateway for route 4.4.4/24. But some Oses have the gateway 2.2.2.2. (treat 4.4.4/24 as a recursive route). > Is there any standard for this? > No, this is entirely implementation specific. Some implementations of IP forwarding resolve the next-hop recursively. Some don't. There is no de facto requirement for them to do so in any published standard I'm aware of. The fact that FreeBSD doesn't is largely out of keeping the implementation simple - if the code were to perform recursive resolution of the next-hop, then safe bounds would need to be found for the recursion. It is cheaper to do this on a forwarding entry add of course, but routes can and do change. BMS