The Innovators: How a Group of Inventors, Hackers, Geniuses, and Geeks Created the Digital Revolutio - Isaacson Walter (книги полностью .txt) 📗
When the Russians tested a hydrogen bomb in 1955, Baran found his life mission: to help prevent a nuclear holocaust. One day at RAND he was looking at the weekly list sent by the Air Force of topics it needed researched, and he seized on one that related to building a military communications system that would survive an enemy attack. He knew that such a system could help prevent a nuclear exchange, because if one side feared that its communications system could be knocked out it would be more likely to launch a preemptive first strike when tensions mounted. With survivable communications systems, nations would not feel the need to adopt a hair-trigger posture.
Donald Davies (1924–2000).
Paul Baran (1926–2011).
Leonard Kleinrock (1934– ).
Vint Cerf (1943– ) and Bob Kahn (1938– ).
Baran came up with two key ideas, which he began publishing in 1960. His first was that the network should not be centralized; there should be no main hub that controlled all the switching and routing. Nor should it even be merely decentralized, with the control in many regional hubs, like AT&T’s phone system or the route map of a major airline. If the enemy took out a few such hubs, the system could be incapacitated. Instead control should be completely distributed. In other words, each and every node should have equal power to switch and route the flow of data. This would become the defining trait of the Internet, the ingrained attribute that would allow it to empower individuals and make it resistant to centralized control.
He drew a network that looked like a fishnet. All of the nodes would have the power to route traffic, and they were each connected to a few other nodes. If any one of the nodes was destroyed, then the traffic would just be routed along other paths. “There is no central control,” Baran explained. “A simple local routing policy is performed at each node.” He figured out that even if each node had only three or four links, the system would have almost unlimited resilience and survivability. “Just a redundancy level of maybe three or four would permit almost as robust a network as the theoretical limit.”55
“Having figured out how to get robustness, I then had to tackle the problem of getting signals through this fishnet type of network,” Baran recounted.56 This led to his second idea, which was to break up the data into standard-size little blocks. A message would be broken into many of these blocks, each of which would scurry along different paths through the network’s nodes and be reassembled when they got to their destination. “A universally standardized message block would be composed of perhaps 1024 bits,” he wrote. “Most of the message block would be reserved for whatever type data is to be transmitted, while the remainder would contain housekeeping information such as error detection and routing data.”
Baran then collided with one of the realities of innovation, which was that entrenched bureaucracies are resistant to change. RAND recommended his packet-switched network idea to the Air Force, which, after a thorough review, decided to build one. But then the Department of Defense decreed that any such undertaking should be handled by the Defense Communications Agency so that it could be used by all of the service branches. Baran realized that the Agency would never have the desire or the ability to get it done.
So he tried to convince AT&T to supplement its circuit-switched voice network with a packet-switched data network. “They fought it tooth and nail,” he recalled. “They tried all sorts of things to stop it.” They would not even let RAND use the maps of its circuits, so Baran had to use a leaked set. He made several trips to AT&T headquarters in lower Manhattan. On one of them, a senior executive who was an old-fashioned analog engineer looked stunned when Baran explained that his system would mean that data could go back and forth without a dedicated circuit remaining open the whole time. “He looked at his colleagues in the room while his eyeballs rolled up sending a signal of his utter disbelief,” according to Baran. After a pause, the executive said, “Son, here’s how a telephone works,” and proceeded with a patronizing and simplistic description.
When Baran continued to push his seemingly preposterous notion that messages could be chopped up and skedaddle through the net as tiny packets, AT&T invited him and other outsiders to a series of seminars explaining how its system really worked. “It took ninety-four separate speakers to describe the entire system,” Baran marveled. When it was over, the AT&T executives asked Baran, “Now do you see why packet switching wouldn’t work?” To their great disappointment, Baran simply replied, “No.” Once again, AT&T was stymied by the innovator’s dilemma. It balked at considering a whole new type of data network because it was so invested in traditional circuits.57
Baran’s work eventually culminated in eleven volumes of detailed engineering analysis, On Distributed Communications, completed in 1964. He insisted that it not be classified as secret because he realized such a system worked best if the Russians had one as well. Although Bob Taylor read some of it, no one else at ARPA did, so Baran’s idea had little impact until it was brought to the attention of Larry Roberts at the 1967 Gatlinburg conference. When he returned to Washington, Roberts unearthed Baran’s reports, dusted them off, and began to read.
Roberts also got hold of the papers written by Donald Davies’s group in England, which Scantlebury had summarized in Gatlinburg. Davies was the son of a Welsh coal mine clerk who died a few months after his son was born, in 1924. Young Davies was raised in Portsmouth by his mother, who worked for Britain’s General Post Office, which ran the nation’s telephone system. He spent his childhood playing with telephone circuits, then earned degrees in math and physics at Imperial College in London. During the war he worked at Birmingham University creating alloys for nuclear weapons tubes as an assistant to Klaus Fuchs, who turned out to be a Soviet spy. He went on to work with Alan Turing building the Automatic Computing Engine, a stored-program computer, at the National Physical Laboratory.
Davies developed two interests: computer time-sharing, which he had learned about during a 1965 visit to MIT, and the use of phone lines for data communications. Combining these ideas in his head, he hit upon the goal of finding a method similar to time-sharing for maximizing the use of communications lines. This led him to the same concepts that Baran had developed about the efficiency of bite-size message units. He also came up with a good old English word for them: packets. In trying to convince the General Post Office to adopt the system, Davies ran into the same problem that Baran had when knocking on the door of AT&T. But they both found a fan in Washington. Larry Roberts not only embraced their ideas; he also adopted the word packet.58
A third and somewhat more controversial contributor in this mix was Leonard Kleinrock, a joyful, affable, and occasionally self-promoting expert on the flow of data in networks, who became close friends with Larry Roberts when they shared an office as doctoral students at MIT. Kleinrock grew up in New York City in a family of poor immigrants. His interest in electronics was sparked when, at the age of six, he was reading a Superman comic and saw instructions for building a crystal radio with no battery. He pieced together a toilet paper roll, one of his father’s razor blades, some wire, and graphite from a pencil, and then convinced his mother to take him on the subway to lower Manhattan to buy a variable capacitor at an electronics store. The contraption worked, and a lifelong fascination with electronics blossomed. “I still am awed by it,” he recalled of the radio. “It still seems magical.” He began scoring radio tube manuals from surplus stores and scavenging discarded radios from Dumpsters, picking apart their components like a vulture so he could build his own radios.59
