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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>
Cc:        sthaug@nethelp.no, net@freebsd.org
Subject:   Re: use of non-contiguous masks in address lookups ?
Message-ID:  <20120524120711.GB59250@onelab2.iet.unipi.it>
In-Reply-To: <98091B3E-B728-483F-99FE-C65BD82CA089@lists.zabbadoz.net>
References:  <20120524071055.GA50710@onelab2.iet.unipi.it> <20120524.094321.74735847.sthaug@nethelp.no> <98091B3E-B728-483F-99FE-C65BD82CA089@lists.zabbadoz.net>

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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


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