From the ‘flag’ day files:
Thirty years ago, something that we could never do today in the networking world, changed our world.
On January 1st 1983, the ‘old’ Internet (aka ARPANET) shut down connectivity to all hosts running the NCP protocol. That’s right, a total shutoff, a ‘flag’ day where one service just ended. NCP had to die for the modern Internet to be born.
In its place, TCP/IP became the networking protocol for ARPANET and the Internet itself.
Back in 1983 there were only some 400 host on ARPANET though, so it was only 400 hosts that had to change. Contrast that with today and tens of millions of hosts and it becomes very clear that the scale of the modern Internet precludes any immediate protocol evolution.
Simply put, today we can’t just simply create a flag day, end one protocol and start another.
Just think about the transition to IPV6. If this was 1983, the powers that be would just declare a flag day (as they did with NCP) after which point we’d all be running IPv6. Instead, the problem of scale means that any change on the modern Internet at a protocol level is now evolutionary over a long period of time.
That’s not necessarily a bad thing. It means stability and longer term resilience for existing systems.
I don’t think that back in 1983 anyone could have possibly predicted that 30 years later, TCP/IP (in much the same form as it originally was born) still dominates network traffic today.
“I can assure you while we had high hopes, we did not dare to assume that the Internet would turn into the worldwide platform it’s become,” Vint Cerf wrote in a recent blog post.