40th Anniversary of the TCP Protocol

In May of 1974, the IEEE published a paper titled “A Protocol for Packet Network Intercommunication.” The authors were Vint Cerf and Bob Kahn.

Forty years later, the protocol they developed, TCP, is still the undisputed king of “sending stuff.” It’s no longer alone in packet types, but we still use the conventions for routing and interconnecting networks that TCP established, and the basic operation hasn’t changed since 1974.

It’s a brilliant design; one that, at its most simple, comes down to a single idea: it doesn’t matter where the packets come from, how fast they get there, what order they get there, or even how many copies there are of that packet on the network – so long as they get there.

The TCP receiver can simply reassemble the sequence as it was originally transmitted, and double-check with the sending computer to ensure accuracy. The TCP slow-start means that it automatically determines the safe rate at which to send packets.

The upshot of all of this has been that TCP enabled, for the first time, the building of robust computer networks. Its reliability made it a standard for interconnectivity in early networks. It made computer networks feasible for people to rely on. Without TCP, you could have networks. You could even have interconnected networks. You probably wouldn’t want to do anything important on them, though.

The Internet has had many “founding moments,” but all of them ultimately relied on the simple interconnectivity and reliability that TCP, and the related IP protocol, brought.

And the impact that the Internet has had on our lives? Well, maybe Vint Cerf said it best in RFC3271, published in 2002:


“The Internet is proving to be one of the most powerful amplifiers of speech ever invented. It offers a global megaphone for voices that might otherwise be heard only feebly, if at all…The Internet is becoming the repository of all we have accomplished as a society.”


We cannot predict the Internet’s growth 40 months down the road, let alone the next 40 years; but who could have imagined such a small thing having such a great impact upon the world, from 1974?