nanog mailing list archives
Re: Stupid Question maybe?
From: William Allen Simpson <william.allen.simpson () gmail com>
Date: Wed, 19 Dec 2018 10:19:28 -0500
On 12/18/18 8:38 PM, Fred Baker wrote:
On Dec 19, 2018, at 3:50 AM, Brian Kantor <Brian () ampr org> wrote:/24 is certainly cleaner than 255.255.255.0. I seem to remember it was Phil Karn who in the early 80's suggested that expressing subnet masks as the number of bits from the top end of the address word was efficient, since subnet masks were always a series of ones followd by zeros with no interspersing, which was incorporated (or independently invented) about a decade later as CIDR a.b.c.d/n notation in RFC1519. - BrianActually, not really. In the time frame, there was quite a bit of discussion about "discontiguous" subnet masks, which were masks that had at least one zero somewhere within the field of ones. There were some who thought they were pretty important. I don't recall whether it was Phil that suggested what we now call "prefixes" with a "prefix length", but it was not fait accompli.
Actually, Brian is correct. Phil was w-a-y ahead of the times. But I don't remember him talking about it until the late '80s. Brian probably knew him longer. Anyway, Fred is also correct. It took many years, and a lot of argument, before prefixes were common. Partly that was me, in PIPE/SIP/SIPP and CIDRD. Required longest prefix match in early Neighbor Discovery drafts. However, I was more of an advocate for suffixes, also known as host mask, wanting them to be common between IPv4 and IPv6. I still think it would have simplified setup for operators. Most don't care how long the network part, they know how many nodes are needed on the LAN. Cisco had adopted /n for network prefixes, so I'd proposed //h for host suffixes. Anyway, /n made it into RFCs.
Going with prefixes as we now describe them certainly simplified a lot of things. Take a glance at https://www.google.com/search?q=discontiguous+subnet+masks for a history discussion.
Didn't see anything ancient. Circa 2010 arguments.... Apparently, CIDRD archives aren't up anymore.
Current thread:
- Re: Stupid Question maybe?, (continued)
- Re: Stupid Question maybe? Saku Ytti (Dec 20)
- Re: Stupid Question maybe? Joel Halpern (Dec 20)
- Re: Stupid Question maybe? Tony Finch (Dec 24)
- Re: Stupid Question maybe? Chuck Church (Dec 26)
- Re: Stupid Question maybe? Baldur Norddahl (Dec 18)
- RE: Stupid Question maybe? Naslund, Steve (Dec 18)
- Re: Stupid Question maybe? William Herrin (Dec 18)
- RE: Stupid Question maybe? Naslund, Steve (Dec 18)
- Re: Stupid Question maybe? Florian Weimer (Dec 21)
- Re: Stupid Question maybe? Fred Baker (Dec 18)
- Re: Stupid Question maybe? William Allen Simpson (Dec 19)
- Re: Stupid Question maybe? Grant Taylor via NANOG (Dec 18)
- Re: Stupid Question maybe? Brandon Martin (Dec 18)
- Re: Stupid Question maybe? James R Cutler (Dec 18)
- Re: Stupid Question maybe? Brandon Martin (Dec 18)
- Re: Stupid Question maybe? tim () pelican org (Dec 19)