The Future = Now x Acceleration

Paul Baran, packet switching and AT&T groupthink

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In keeping with the theme of this week’s readings regarding the Internet of the 1990s and the podcast covering the Victorian internet of the 1850s (the electric telegraph,) this post is about an inventor without whose contribution, the modern Internet wouldn’t be what it is today.

One year ago this month, (March,) Paul Baran died at 84. you may not have ever heard of him, but he created packet switching while at the RAND Corporation in the 1960s. Packet switching is at the heart of how data flows through the Internet using TCP / IP.

In the same way that Xerox PARC invented the graphical user interface for computers but couldn’t conceive a practical application for it, Paul Baran attempted to share the technology with AT&T in order to establish a test network with its phone lines but Ma Bell wouldn’t have it. As Baran later told Wired Magazine, the “old graybeards” at AT&T just didn’t understand the nature of digital transmission.

Paul Baran: I start describing how this works. One stops me and says, “Wait a minute, son. Are you trying to tell us that you open the switch up in the middle of the conversation?” I say, “Yes.” His eyeballs roll as he looks at his associates and shakes his head. We just weren’t on the same wavelength.

If you think in analog terms, the signal arrives instantaneously. If you think in digital terms, time moves very, very slowly, and you can do things like change the path while you’re in the middle of a syllable. But it was a mental block. They didn’t understand digital.”

If AT&T would have gotten the concept, it could have had a monopoly on the architecture of the Internet. As it is, the company is now just one of a number of domestic telecoms that share the Internet backbone and its spoils.

Baran’s work on a solution to a military command and control problem is, perhaps, the origin of the urban legend that the ARPANET was constructed from the outset to survive a nuclear warfare attack. Not so, says Baran.

“Wired: The myth of the Arpanet – which still persists – is that it was developed to withstand nuclear strikes. That’s wrong, isn’t it?

Paul Baran: Yes. Bob Taylor1 had a couple of computer terminals speaking to different machines, and his idea was to have some way of having a terminal speak to any of them and have a network. That’s really the origin of the Arpanet. The method used to connect things together was an open issue for a time.”

That method of connecting things together evolved over time to Baran’s packet switching idea. That was the idea that gave the Internet its limited survivability – the ability to route and re-route data around damaged nodes. Surprisingly, while Baran was trying to get the phone company to implement digital packet switching, the first implementation of a working packet switched network was secretly carried out right under the nose of the American public using AM radio stations.

Paul Baran: Sometimes certain terms take on a meaning of their own and become real. One was “minimum essential communications.” The military said all they wanted was “minimum essential communications,” and I believed them. So I thought data rate would take care of everything – get the word out, calm things down if necessary. You don’t need a hell of a lot of communication for that.

So then I picked up on an idea from Frank Collbohm that the problem is the military depends heavily on high-frequency communications. A high-altitude nuclear burst takes out the ionosphere11 for many hours. So the only thing that was left was the ground wave12 – that’s what you get from broadcast stations during the day in the short range. Collbohm’s idea was for the radio stations to relay the message from one to the other. But there are a lot of them in the US. So I said, “Let’s automate it.” That would make it practical.

The first crack that I took at it in 1960, I got an old Johniac computer and a plotting board, and I plotted the locations of all the AM13 radio stations in the US. Yeah, there’s plenty of paths; I said look at the range.

That went off in two directions.

One, I went out with a briefing chart, saying, “OK, here’s the solution to your problem.” I got push-back from the military: “That takes care of the president getting word to the missile, but what about me? I’ve got to speak to the troops. I’ve got to do this and that. I need more communication.”

Meanwhile, the Air Force took the idea and gave it to Rome Air Development Center. They built it as a teletypewriter system and tested it. It worked just fine. And they did something cute: They used the AM radio stations, but slightly wobulated their frequency – around 20 Hz. You couldn’t hear it on your radio, but it let us send a frequency-modulated14 teletype signal.

Wired: Was that implemented?

Paul Baran:: Yeah. It was implemented, tested with a dozen stations, and it all worked fine. That may have been the first packet-switching system.

Wired: Let me see if I actually understand this. These were AM stations. And this system is doing frequency modulation on that, so it’s turning these AM stations into secret FM stations for teletype messages of “go” and “no-go” on missiles. That’s diabolical. That’s pretty good.

Paul Baran: I didn’t invent that. Whoever it was at Rome did that.

Wired: Did the AM stations know this was going on?

Paul Baran: I didn’t get involved with it, but I saw a piece in an amateur radio magazine where somebody said that it was a hush-hush program at the time.

Wired: It’s sort of wild. Here are radio stations, who are the ultimate blabbermouths, and you use them as your channel of extremely secret, extremely important communication.

Paul Baran: Really, the issue was, Why don’t we use the telephone system? AT&T was a total monopoly at the time.”

AT&Ts refusal at the time to explore the capabilities of digital switching seems inconceivable now in a world where the company now maintains a great deal of the Internet backbone and bills itself as a force in the digital landline, DSL and mobile markets. It is a cautionary tale about the dangers of organizational “groupthink” and not being tied to closely to the status quo.


Written by digitalanalogues

March 1, 2012 at 5:42 PM

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