From owner-freebsd-net@FreeBSD.ORG  Thu May 24 11:46:48 2012
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 2AA5B106580B
	for <net@freebsd.org>; Thu, 24 May 2012 11:46:48 +0000 (UTC)
	(envelope-from luigi@onelab2.iet.unipi.it)
Received: from onelab2.iet.unipi.it (onelab2.iet.unipi.it [131.114.59.238])
	by mx1.freebsd.org (Postfix) with ESMTP id D91CA8FC1F
	for <net@freebsd.org>; Thu, 24 May 2012 11:46:47 +0000 (UTC)
Received: by onelab2.iet.unipi.it (Postfix, from userid 275)
	id B583973027; Thu, 24 May 2012 14:07:11 +0200 (CEST)
Date: Thu, 24 May 2012 14:07:11 +0200
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net>
Message-ID: <20120524120711.GB59250@onelab2.iet.unipi.it>
References: <20120524071055.GA50710@onelab2.iet.unipi.it>
	<20120524.094321.74735847.sthaug@nethelp.no>
	<98091B3E-B728-483F-99FE-C65BD82CA089@lists.zabbadoz.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <98091B3E-B728-483F-99FE-C65BD82CA089@lists.zabbadoz.net>
User-Agent: Mutt/1.4.2.3i
Cc: sthaug@nethelp.no, net@freebsd.org
Subject: Re: use of non-contiguous masks in address lookups ?
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 24 May 2012 11:46:48 -0000

On Thu, May 24, 2012 at 11:19:54AM +0000, Bjoern A. Zeeb wrote:
> 
> On 24. May 2012, at 07:43 , sthaug@nethelp.no wrote:
> 
> >> every now and then the issue comes up on whether we still need
> >> to support non-contiguous masks in address lookups.
> >> I seem to remember someone (perhaps on this list) making a
> >> case for their presence, but forgot the details.
> >> So, does anyone know of a practical use of non contiguous masks ?
> > 
> > I vote for removing non-contiguous masks. They are incompatible with
> > CIDR, which was introduced in 1993 (!).
> > 
> > Non-contiguous masks have been unsupported in many routers produced
> > the last 10 years or so.
> 
> Contrary I still know people using them and relying on it.  Not sure on
> which version they are.
> 
> I am not quite sure what micro-optimizations on legacy IP will help
> us after a decade or longer.  Let it rest and die gracefully the next
> years.  Of course, fixing bugs still considered good:)

the point of my question was to get [f]actual usage information on non
contiguous masks, because i don't know of any (at least on ipv4,
maybe in ipv6 there is one). The answer does not have to affect
FreeBSD, if that is what worries you.

cheers
luigi