The Internet — in the sense of the network based on the TCP/IP family of protocols — is 30 years old today. Google asked Vint Cerf, who with Robert Kahn was co-designer of the system, to mark the anniversary with a blog post explaining how it came about.

TCP/IP was tested across the three types of networks developed by DARPA, and eventually was anointed as their new standard. In 1981, Jon Postel published a transition plan to migrate the 400 hosts of the ARPANET from the older NCP protocol to TCP/IP, including a deadline of January 1, 1983, after which point all hosts not switched would be cut off.

When the day came, it’s fair to say the main emotion was relief, especially amongst those system administrators racing against the clock. There were no grand celebrations—I can’t even find a photograph. The only visible mementos were the “I survived the TCP/IP switchover” pins proudly worn by those who went through the ordeal!

It’s typical of Vint that he should downplay the brilliance of the TCP idea, not to mention his own role in it. A fuller version of the story is told in my book on the history of the Net. As a taster, here’s the text of the relevant chapter.