On Wed, Oct 3, 2012 at 12:13 PM, Chris Campbell <chris@ctcampbell.com> wrote:
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 “estimated 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.