From owner-freebsd-net@FreeBSD.ORG Tue Apr 6 06:03:34 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 5E6FB16A4CE for ; Tue, 6 Apr 2004 06:03:34 -0700 (PDT) Received: from mailtoaster1.pipeline.ch (mailtoaster1.pipeline.ch [62.48.0.70]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9FAE743D55 for ; Tue, 6 Apr 2004 06:03:33 -0700 (PDT) (envelope-from andre@freebsd.org) Received: (qmail 88735 invoked from network); 6 Apr 2004 13:03:13 -0000 Received: from unknown (HELO freebsd.org) ([62.48.0.53]) (envelope-sender ) by mailtoaster1.pipeline.ch (qmail-ldap-1.03) with SMTP for ; 6 Apr 2004 13:03:13 -0000 Message-ID: <4072AA91.DA00A9F3@freebsd.org> Date: Tue, 06 Apr 2004 15:03:13 +0200 From: Andre Oppermann X-Mailer: Mozilla 4.76 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: Anders Lowinger 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> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit cc: Luigi Rizzo cc: net@freebsd.org 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: Tue, 06 Apr 2004 13:03:34 -0000 Anders Lowinger wrote: > > Andre Oppermann wrote: > > >> interface ethernet 0 > >> ip address 192.168.0.0 mask 255.255.253.0 > > > > This is simply a supernet (aka classless) but *not* a non-contignous > > netmask. A non-contignous netmask would look like 255.254.255.0. > > Nope, 255.255.253.0 binary is 11111111.11111111.11111101.00000000 > which is non-contignous. You are right. I was looking to quickly. However at least my Cisco doesn't like it: "Bad mask 0xFFFFFD00 for address", IOS 12.2(10). > > With the your second example hosts on the network have > > to have different default gateways (192.168.0.1 and 192.168.2.1) > > depending in which network range they are. In your first example > > you just have one default gateway for all of them. However the > > netmask has to match on all hosts otherwise you run into all sorts > > of wierd trouble. > > In this case, the above is normally only used during a migration > phase (as I mentioned, this is the only use of non-contignous i've > seen, joining two separate subnets), so the hosts already have the > correct default-route in their subnet. Hosts could optionally then > be migrated to a common subnet. Never heard of that (only supernets/subnets with respect to classful notation), never done it and at least my Cisco 7500 doesn't like it. So I doubt others have got their Cisco to like it. -- Andre