From IEEE Spectrum, April 30:
Vint Cerf is the recipient of the IEEE Medal of Honor “for cocreating the Internet architecture and providing sustained leadership in its phenomenal growth in becoming society’s critical infrastructure.”
Even after 50 years, he’s still extending and evangelizing the Internet
It was June 1973. For the past three months, Vint Cerf and Bob Kahn had been working together on a problem Kahn had been pondering for some time: how to connect ground-based military computers seamlessly to communications satellites and mobile radios.
The ARPANET and the way it handled communications was already well established. But extending it to handle multiple networks—whose reliability couldn’t be taken for granted—was a different story.
The two had been exchanging ideas in person and via email and reviewing the work of others who were trying to solve similar issues. But now, Cerf sat alone in the lobby of San Francisco’s Jack Tar Hotel, on a break from a computing conference. And the problem was on his mind.
Cerf pulled out an envelope. Recalling what the two had figured out so far, he began to sketch the main components and key interfaces. He scrawled clouds representing three different packet-switched networks—the ARPANET, packet radio, and packet satellite—and boxes representing the computers hanging off those networks. These would be the host computers, running applications that needed to use the network.
“The networks couldn’t be changed and couldn’t know that they were part of the Internet, because they already existed,” Cerf recalls recently in an interview at his office at Google, in Reston, Va.
So he sketched in another set of computers—gateways—that would know about other networks.
“Those were the constraints of the problem,” he says. “Sometimes, if you can constrain a problem enough, you can see the solution pop out in front of you. The diagram helped me to see where protocols would need to be standardized.”
Cerf describes the communication protocols that he and Kahn came up with as comparable to a set of postcards and envelopes: The postcard has a message and an address for the intended destination. The address on the envelope is either that of the destination host in the local network or of a gateway that leads toward the next network along the route to the final destination.
When a message arrives at that next gateway, the gateway opens the envelope and checks the address on the postcard. If the message is intended for a destination inside the gateway’s home network, it gets delivered in an appropriate envelope; if not, it goes in an envelope addressed to the next gateway en route to the destination network, where the process repeats.
That, essentially, is how the Internet works today....
....MUCH MORE
