From owner-freebsd-net@FreeBSD.ORG Thu Apr 8 09:56:41 2004 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 23E6216A4CE for ; Thu, 8 Apr 2004 09:56:41 -0700 (PDT) Received: from phuket.psconsult.nl (ps226.psconsult.nl [213.222.19.226]) by mx1.FreeBSD.org (Postfix) with ESMTP id 363CC43D54 for ; Thu, 8 Apr 2004 09:56:39 -0700 (PDT) (envelope-from fb-net@psconsult.nl) Received: from phuket.psconsult.nl (localhost [127.0.0.1]) by phuket.psconsult.nl (8.12.8p2/8.12.8) with ESMTP id i38GubYe025847 for ; Thu, 8 Apr 2004 18:56:37 +0200 (CEST) (envelope-from fb-net@psconsult.nl) Received: (from paul@localhost) by phuket.psconsult.nl (8.12.8p2/8.12.8/Submit) id i38GubT9025846 for net@freebsd.org; Thu, 8 Apr 2004 18:56:37 +0200 (CEST) Date: Thu, 8 Apr 2004 18:56:37 +0200 From: Paul Schenkeveld To: net@freebsd.org Message-ID: <20040408165637.GA25187@psconsult.nl> Mail-Followup-To: net@freebsd.org References: <20040331005914.A6934@xorpc.icir.org> <40712A8F.9000704@packetfront.com> <40716208.808CF084@freebsd.org> <4072916D.101@packetfront.com> <40729B7A.2C984BD3@freebsd.org> <4072A169.9010206@packetfront.com> <4072AA91.DA00A9F3@freebsd.org> <4072B048.2000509@packetfront.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4072B048.2000509@packetfront.com> User-Agent: Mutt/1.5.6i Subject: Re: do we support non contiguous netmasks ? 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: Thu, 08 Apr 2004 16:56:41 -0000 Hi, On Tue, Apr 06, 2004 at 03:27:36PM +0200, Anders Lowinger wrote: > I was just trying to elaborate on when/why non-contignous netmasks > would be good to have. I'm pretty sure no-one is using them.... Actually, one of my customers uses a non-contiguous netmask for static routes. The picture is something like this: In a WAN they have many branch offices with a standardized IP plan giving 8 subsequent /24 subnets (RFC1918) to each branch. At one point in time it was decided that the second subnet of each branch office should use an ISDN dialup network instead of the VPN because the traffic on that subnet is only occasional but too bursty for the VPN. So the IP plan is: 172.18.bbbbbsss.hhhhhhhh (branches 1 - 32) 172.19.bbbbbsss.hhhhhhhh (branches 33 - 64) where bbbbb is the branch office number (module 32) and sss the subnet number within the branch office. They have the following two routes on their central (FreeBSD) routers at the main office: route add -net 172.18.0.0 -netmask 255.254.0.0 vpn-router route add -net 172.18.1.0 -netmask 255.254.7.0 isdn-router Not having non-contiguous netmask would require them to install 65 static routes: route add -net 172.18.0.0 -netmask 255.254.0.0 vpn-router route add -net 172.18.1.0 -netmask 255.255.255.0 isdn-router route add -net 172.18.2.0 -netmask 255.255.255.0 isdn-router route add -net 172.18.3.0 -netmask 255.255.255.0 isdn-router ... route add -net 172.19.255.0 -netmask 255.255.255.0 isdn-router I agree that this use of non-contiguous netmasks is rare and I would not object against removing them from FreeBSD if is serves the purpose of better/faster/easier to understand/higher quality/easier to maintain kernel code (and tell my customer that I'm sorry but we move to 65 static routes up from 2). Greetings, Paul Schenkeveld, Consultant PSconsult ICT Services BV