[157054] in North American Network Operators' Group
Re: IPv4 address length technical design
daemon@ATHENA.MIT.EDU (Bjorn Leffler)
Thu Oct 4 11:40:51 2012
In-Reply-To: <3BDE1550-5D07-46E9-A667-33C416E74FC6@ctcampbell.com>
From: Bjorn Leffler <bjorn@leffler.org>
Date: Thu, 4 Oct 2012 11:39:46 -0400
To: Chris Campbell <chris@ctcampbell.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Wed, Oct 3, 2012 at 12:13 PM, Chris Campbell <chris@ctcampbell.com> wrot=
e:
>
> Is anyone aware of any historical documentation relating to the choice of=
32 bits for an IPv4 address?
I've heard Vint Cerf say this himself, but here's a written reference
for you. They had just finished building arpanet, which was expensive
to build. Hence why they estimated two networks per country.
http://www.domainpulse.com/2012/06/06/world-ipv6-day/
When developing IPv4, Cerf said that he and Bob Kahn =93estimated that
there might be two national-scale packet networks per country and
perhaps 128 countries able to build them, so 8 bits sufficed for 256
network identifiers. Twenty-four bits allowed for up to 16 million
hosts. At that time, hosts were big, expensive time-sharing systems,
so 16 million seemed like a lot. We did consider variable length and
128-bit addressing in 1977 but decided that this would be too much
overhead for the relatively low-speed lines (50 kilobits per second).
I thought this was still an experiment and that if it worked we would
then design a production version.
