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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