The Internet’s Physical Infrastructure

To this point, we have focused mostly on the Internet’s logical layer char-acteristics. Now we shift our focus to the physical layer, which is the site of most, though by no means all, Internet-related telecommunications policy disputes.

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A. Beginnings

A brief synopsis of the Internet’s origins helps explain its close relationship to the traditional telecommunications infrastructure. In the usual telling, the Internet is described as the brainchild of the same military-industrial complex that brought us the theory of Mutually Assured Destruction. In the 1960s, at the height of the Cold War, some of America’s brightest minds were fixated on a macabre question: If the Soviet Union wiped out much of the United States in a preemptive nuclear strike, how could the president convey a “launch” order to America’s own assembled nuclear forces? For Paul Baran, then a technologist at Rand, the answer to this telecommuni-cations problem seemed obvious: build a network with a series of broadly interconnected nodes(routers) so that no one node is critical to the func-tioning of the network as a whole.

The problem was that the military’s long distance communications infrastructure was largely contained within AT&T’s circuit-switched work. As we discussed in chapter 2, an efficient circuit-switched voice net-work conserves on switching capacity by economizing on the number of switches that need to be occupied for the duration of a voice call. This requires a highly centralized network with a rigid hierarchy of switches.

The efficiency of that hierarchical arrangement, however, is also its great-est military vulnerability. Precisely because it was centralized and hierarchi-cal, AT&T’s circuit-switched network was exceptionally susceptible to destruction. If the Soviets could hit just a few central switches, they might have been able to prevent Washington from sending messages to missile silos in Nebraska, Arizona, and Montana. The solution was a digital and

“distributed” (decentralized) network developed by a taxpayer-supported think tank within the Defense Department known as the Advanced Research Projects Agency, or “ARPA.”

Like the nodes in Baran’s imagined distributed network, each of the nodes in the ARPANet was linked to several other nodes in a generally non-hierarchical way that maximized the number of routes a signal could take from Point A to Point B. One node would hand off a message to another with the destination information attached, the next node would hand it off to yet a third node with the same destination information, and so on down the line until the destination was reached. If one node along the way was out of commission, the message could be rerouted to another,

still-active node. Thus, even though the ARPANet still leased its transport links from AT&T, it was much less vulnerable than AT&T’s own circuit-switched network. Just as Baran had envisioned, if half of the ARPANet had been wiped out in an attack, signals still would have arrived at missile silos or any other critical governmental location, albeit in a more round-about way.

For the ARPANet to work, however, the messages had to be transmit-ted in digital form, in part because that is the only feasible way of preserv-ing the clarity and integrity of messages after frequent repetition at many nodes. And the network could operate efficiently only if it was packet-switched, for, as we have explained, packet-switching technology enables the portions of a “call” (or “session”) to hop through a large number of nodes in small packets without needlessly tying up capacity on each of those nodes in the form of dedicated “circuits.”

The ARPANet also accomplished a number of relatively mundane objectives, such as linking together government-supported labs for purpos-es of aggregating the procpurpos-essing power of the mainframe computers in each lab. Indeed, some observers submit that the government funded the ARPANet project more to achieve such conventional objectives than, as in Baran’s vision, to preserve communications in the event of a catastrophic attack.²⁰Nonetheless, the distributed and digital character of this network, conceived amid the Cold War paranoia of the 1960s, forms the basis for the current Internet.

To be sure, today’s Internet differs from the original ARPANet in sev-eral important respects. The ARPANet started out as a single unified net-work overseen by the government and affiliated research institutions. The main applications from the 1970s through the birth of the modern Internet in the early 1990s were file exchanges (employing the now outdated but still used File Transfer Protocol), TELNET (a means of logging on remote-ly to a mainframe computer), newsgroups, and e-mail.²¹The most influen-tial users were academics who relied on government funding to develop the basic protocols on which the Internet still relies. And the federal govern-ment’s sponsorship was critical throughout these early years. ARPA fund-ed a Berkeley program to incorporate TCP/IP into the UNIX operating system; the Defense Department required its contractors to adopt TCP/IP;

and the National Science Foundation provided grants to the IETF and invested more than $200 million to support “NSFNet,” a TCP/IP network that linked the networks of various universities.²²

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This official sponsorship finally ended in the early 1990s, when the fed-eral government proposed to privatize the NSFNet and, for the first time, open it up to commercial uses.²³The government thereby sought to enlist

“the enthusiasm of private sector interests to build upon the government funded developments to expand the Internet and make it available to the general public,” as two Internet pioneers have observed.²⁴

The result of this privatization decision is the wildly successful modern Internet. On the physical and logical layers, it is a decentralized network of dissimilar networks with otherwise incompatible computers and other smart devices joined together by their common use of the TCP/IP set of protocols. On the higher layers, it is an engine for economic growth and an unrivaled resource for electronic applications and content, whose variety is bounded only by the limits of the human imagination. By 1997, it had become conventional wisdom that, in the words of Bill Clinton and Al Gore, “[t]he private sector should lead” the Internet’s continued growth and that, although the government had played a critical role in the Internet’s development, “its expansion has been driven primarily by the pri-vate sector.”²⁵