From owner-freebsd-isp@FreeBSD.ORG Wed Jul 30 06:01:16 2003 Return-Path: Delivered-To: freebsd-isp@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4836D37B401; Wed, 30 Jul 2003 06:01:16 -0700 (PDT) Received: from dire.bris.ac.uk (dire.bris.ac.uk [137.222.10.60]) by mx1.FreeBSD.org (Postfix) with ESMTP id 472AE43FA3; Wed, 30 Jul 2003 06:01:15 -0700 (PDT) (envelope-from Jan.Grant@bristol.ac.uk) Received: from mail.ilrt.bris.ac.uk by dire.bris.ac.uk with SMTP-PRIV with ESMTP; Wed, 30 Jul 2003 14:01:12 +0100 Received: from cmjg (helo=localhost) by mail.ilrt.bris.ac.uk with local-esmtp (Exim 3.16 #1) id 19hqYF-0006bf-00; Wed, 30 Jul 2003 13:59:31 +0100 Date: Wed, 30 Jul 2003 13:59:31 +0100 (BST) From: Jan Grant X-X-Sender: cmjg@mail.ilrt.bris.ac.uk To: =?iso-8859-1?q?Supote=20Leelasupphakorn?= In-Reply-To: <20030730124609.40316.qmail@web40614.mail.yahoo.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: Jan Grant cc: freebsd-isp cc: freebsd-net cc: freebsd-questions@freebsd.org Subject: Re: Can I subnet my network like this ? X-BeenThere: freebsd-isp@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Internet Services Providers List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Jul 2003 13:01:16 -0000 On Wed, 30 Jul 2003, [iso-8859-1] Supote Leelasupphakorn wrote: > Hi, all > > I would like to verify my knowledge > by building the network like below but not > sure whether it's impossible for subnetting > like this - say, from Gateway no2, is divided > to 172.16.0.0/16 and 172.17.0.0/16 subnet. There should be no problems doing what you suggest. > I heard that it isn't recommend or > impossible (not sure again) to use FIRST or > LAST subnet in the allocated IP address pool, > is it? This is no longer the case. It stems from (a misunderstanding of?) the "all zeros" or "all ones" network treatment (and by extension, subnets), but I don't think any kit behaves like that in these CIDR days. In any case, 172.16/16 and 172.17/16 are (were) both "full class B" ranges so anything broken enough to care ought to behave properly anyway. -- jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/ Tel +44(0)117 9287088 Fax +44 (0)117 9287112 http://ioctl.org/jan/ Random act of violence against bread: whole pint. -- extract from the "Hawk the Slayer" drinking game