13. Internet

Timeline 

Beginning as a tool for a select group of engineers and scientists associated with academia or government and evolving rapidly into the World Wide Web open to anyone with a computer and a telephone connection, the Internet has transformed the way we conduct research, communicate, and make purchases ranging from groceries and airline tickets to the latest books and music or clothing and furniture. How we got from there to here on the information highway is the story of a host of individuals and breakthrough thinking.

Packets 

In the conference hall at the hotel was an array of terminals whose software permitted interactions with computers hundreds or thousands of miles away. The invitees were encouraged to experiment—try out an air traffic control simulator, play chess against an electronic foe, explore databases. There had been some problems in setting up the demonstrations. At one point, a file meant to go to a printer in the hall was mistakenly directed to a robotic turtle, resulting in a wild dance. But it all worked when it had to, convincing the doubters and engaging their interest so effectively that, as one of the organizers said, they were "as excited as little kids." Within a month, traffic on the network increased by two-thirds. In a few more years, ARPANET hooked up with other networks to become a connected archipelago called the Internet. By the end of the 20th century, more than 100 million people were thronging Internet pathways to exchange e-mail, chat, check the news or weather, and, often with the aid of powerful search engines to sift for useful sites, navigate the vast universe of knowledge and commerce known as the World Wide Web. Huge electronic marketplaces bloomed. Financial services, the travel industry, retailing, and many other businesses found bountiful opportunities online. Across the world, the connecting of computers via the Internet spread information and rearranged human activities with seismic force.

All this began in an obscure branch of the U.S. Department of Defense called the Advanced Research Projects Agency, or ARPA. In the 1960s a number of computer scientists at universities and research laboratories across the country received ARPA funding for projects that might have defense-related potential—anything from graphics to artificial intelligence. With the researchers' needs for processing power steadily growing, ARPA decided to join its scattered mainframes into a kind of cooperative, allowing the various groups to draw on one another's computational resources. Responsibility for creating the network was assigned to Lawrence Roberts, a young computer scientist who arrived at ARPA from the Massachusetts Institute of Technology in 1966.

Roberts was aware of a promising approach in the ideas of an MIT classmate, Leonard Kleinrock, and he later learned of related work by two other communications experts, Paul Baran and Donald Davies. Kleinrock had written his doctoral dissertation on the flow of messages in communications networks, exploring the complexities of moving data in small chunks. At about the same time, Baran proposed a different kind of telephone network, which would turn the analog signal of a telephone into digital bits, divide the stream into blocks, and send the blocks in several different directions across a network of high-speed switches or nodes; the node nearest the destination would put the pieces back together again. Davies proposed a similar scheme, in which he called the chunks or blocks "packets," as in packet switching, and that name stuck.

Roberts, for his part, was convinced that the telephone system's method of routing signals, called circuit switching, was poorly suited for linking computers: to connect two callers, a telephone switch opens a circuit, leaving it open until the call is finished. Computers, however, often deliver data in bursts and thus don't need full-time possession of a connection. Packet switching seemed the obvious choice for ARPA's network, not only enabling several computers to share a circuit but also countering congestion problems: when one path was in heavy use, a packet could simply take another route.

ARPANET

Initially, Roberts intended to have the switching done by the mainframes that ARPA wanted to connect. But small, speedy minicomputers were just then appearing, and an adviser, Wesley Clark of Washington University in St. Louis, persuaded him to assign one of them to each of the research centers as a switch. Unlike the mainframes, which came from a variety of manufacturers, these so-called interface message processors, or IMPs, could have standardized routing software, which would save on programming costs and allow easy upgrades. In early 1969 the job of building and operating the network was awarded to the consulting firm of Bolt Beranek and Newman, Inc. (BBN), in Cambridge, Massachusetts. Although modest in size, BBN employed a stellar cast of engineers and scientists, drawn largely from nearby Harvard University and MIT.

Roberts had outlined what the IMPs would do. First, they would break data from a host mainframe into packets of about 1,000 bits each, attaching source and destination information to each packet, along with digits used to check for transmission errors. The IMPs would then choose optimal routes for the individual packets and reassemble the message at the other end. All the traffic would flow on leased telephone lines that could handle 50,000 bits per second. The BBN team, led by Robert Kahn of MIT, worked out the details and devised an implementation strategy. ARPANET was up and running at four sites by late 1969. At first, just four time-sharing computers were connected, but more hosts and nodes quickly followed, and the network was further expanded by reconfiguring the IMPs so they could accept data from small terminals as well as mainframes.

The nature of the traffic was not what ARPA had expected, however. As time went on, the computer scientists on the network used it primarily for personal communication rather than resource sharing. The first program for sending electronic mail from one computer to another was written in 1972—almost on a whim—by Ray Tomlinson, an engineer at BBN. He earned a kind of alphanumerical immortality in the process. For his addressing format he needed a symbol to clearly separate names from computer locations. He looked at the keyboard in front of him and made a swift choice: "The one that was most obvious was the @ sign, because this person was @ this other computer," he later explained. "At the time, there was nobody with an @ sign in their name that I was aware of." Trillions of e-mails would be stamped accordingly.

TCP/IP

Packet switching soon found favor beyond the confines of ARPANET. Roberts left ARPA in 1972 to become president of one of the first companies to offer networking services to commercial customers. Several European countries had become interested in computer networking, and the U.S. government had other packet-based projects under way. Although ARPANET was presumably destined to remain a well-guarded dominion of computer scientists, some widening of its reach by connecting with other networks seemed both desirable and inevitable.

It was clear to Robert Kahn, who had headed the BBN design team, that network-to-network linkages would require an acceptance of diversity, since ARPANET's specifications for packet sizes, delivery rates, and other features of data flow were not a standard. Commonality would instead be imposed in the form of shared rules, or protocols, for communication—some of the rules to apply to the networks themselves, others meant for gateways that would be placed between networks. The job of these gateways, called routers, would be to control traffic, nothing more. What was inside the packets wouldn't matter.

To grapple with the various issues, Kahn joined forces with Vinton Cerf, who had been involved in designing the ARPANET protocols for host computers and also had experience with time-sharing systems on the ARPANET. By mid-1974 their recommendations for an overall network-to-network architecture had been accepted. Negotiations to finalize the two sets of rules, jointly known as TCP/IP (transmission control protocol/ internet protocol), took several more years, and ARPANET did not formally incorporate the new system until 1983. By then ARPA—now known as DARPA, the "D" having been added to signal a clearer focus on defense—was looking for release from its network responsibilities.

An exit presented itself in mid-decade when another U.S. government entity, the National Science Foundation (NSF), began building five supercomputing centers around the country, along with a connecting backbone of lines that were about 25 times faster than ARPANET's. At that time, research scientists of all kinds were clamoring for network access to allow the kind of easy communication and collaboration that ARPANET users had long enjoyed. NSF answered the need by helping to create a number of regional networks, then joining them together by means of the supercomputer backbone. Many foreign networks were connected. In the late 1980s ARPANET began attaching its sites to the system, and in 1990 the granddaddy of packet-switching networks was decommissioned.

World Wide Web

Meanwhile, beyond the world of science, computer networking spread in all directions. Within corporations and institutions, small computers were being hooked together in local area networks, which typically used an extremely fast, short-range packet delivery technique called Ethernet (invented by one-time ARPANET programmer Robert Metcalfe back in 1973) and were easily attached to outside networks. On a nation-spanning scale, a number of companies built high-speed networks that could be used to process point-of-sale transactions, give corporate customers access to specialized databases, and serve various other commercial functions. Huge telecommunications carriers such as AT&T and MCI entered the business. As the 1990s proceeded, the major digital highways, including those of NSF, were linked, and on-ramps known as Internet service providers proliferated, providing customers with e-mail, chat rooms, and a variety of content via telephone lines and modems. The Internet was now a vast international community, highly fragmented and lacking a center but a miracle of connectivity.

What allowed smooth growth was the TCP/IP system of rules originally devised for attaching other networks to ARPANET. Over the years rival network-to-network protocols were espoused by various factions in the computer world, among them big telecommunications carriers and such manufacturers as IBM. But TCP/IP worked well. It was highly flexible, it allowed any number of networks to be hooked together, and it was free. The NSF adopted it, more and more private companies accepted it, and computer scientists overseas came to prefer it. In the end, TCP/IP stood triumphant as the glue for the world's preeminent network of networks.

In the 1990s the World Wide Web, an application designed to ride on top of TCP/IP, accelerated expansion of the Internet to avalanche speed. Conceived by Tim Berners-Lee, a British physicist working at the CERN nuclear research facility near Geneva, it was the product, he said, of his "growing realization that there was a power in arranging ideas in an unconstrained, weblike way." He adopted a venerable computer sciences idea called hypertext—a scheme for establishing nonlinear links between pieces of information—and came up with an architectural scheme for the Internet era. His World Wide Web allowed users to find and get text or graphics files—and later video and audio as well—that were stored on computers called servers. All the files had to be formatted in what he termed hypertext markup language (HTML), and all storage sites required a standardized address designation called a uniform resource locator (URL). Delivery of the files was guided by a set of rules known as the hypertext transfer protocol (HTTP), and the system enabled files to be given built-in links to other files, creating multiple information paths for exploration.

Revolution

Although the World Wide Web rapidly found enthusiasts among skilled computer users, it didn't come into its own until appealing software for navigation emerged from a supercomputing center established at the University of Illinois by NSF. There, two young computer whizzes named Marc Andreessen and Eric Bina created a program called Mosaic, which made Web browsing so easy and graphically intuitive that a million copies of the software were downloaded across the Internet within a few months of its appearance in April 1993. The following year Andreessen helped form a company called Netscape to produce a commercial version of Mosaic. Other browsers soon followed, and staggering quantities of information moved onto servers: personal histories and governmental archives; job listings and offerings of merchandise; political tracts, artwork, and health information; financial news, electronic greeting cards, games, and uncountable other sorts of human knowledge, interest, and activity—with the whole indescribable maze changing constantly and growing exponentially.

By the end of the 20th century the Internet embraced some 300,000 networks stretching across the planet. Its fare traveled on optical fibers, cable television lines, and radio waves as well as telephone lines—and the traffic was doubling annually. Cell phones and other communication devices were joining computers in the vast weave. Some data are now being tagged in ways that allow Web sites to interact. What the future will bring is anyone's guess, but no one can fail to be amazed at the dynamism of networking. Vinton Cerf, one of the Internet's principal designers, says simply: "Revolutions like this don't come along very often."

Essay - Robert E. Kahn

Robert E. Kahn
President
Corporation for National Research Initiatives

My first experience with computers, aside from a brief episode toggling the switches on an early IBM model 650, was with the IBM 704, 709, and finally 7090 at Bell Laboratories in the early 1960s. In those days we submitted computer programs to large "batch-processing" machines via punched cards, carrying them by hand to the computer center for processing later. It usually took several tries to fully debug even relatively simple programs, which usually translated into several days of elapsed time from start to finish.

The introduction of time-sharing procedures, which allowed several users to take turns using the same computer via teletype machines, made it possible to debug programs interactively, thus shortening the time to create working programs. Eventually we were doing this over telephone lines, at initial speeds of 300 bits per second. However, errors on the phone lines, along with the high cost of long-distance telephony and error correction, made interactive computer communications impractical over long distances.

The ARPANET, which leased 50-kilobit-per-second lines from the telephone company, was a significant improvement, allowing messages to be communicated between computers in the United States in a fraction of a second using a technique called packet switching. During the 1970s, more than 100 time-sharing machines were connected to the ARPANET and many thousands of researchers could access remote machines, do computations involving multiple machines, and even make use of specialized facilities such as the ILLIAC IV, the world's first supercomputer.

When I began working at DARPA (Defense Advanced Research Projects Agency) in the early 1970s, I recognized a need for multiple networks to communicate. I invited a colleague, Vint Cerf, to work with me in creating a logical architecture for connecting multiple networks and the computers attached to them. The key ingredients of this architecture were a protocol, now known as TCP/IP (transmission control protocol/internet protocol), with Internet addresses (i.e., IP addresses) to identify the individual machines and gateways (now known as routers) to provide linkages among networks. The networks that constituted the initial Internet were the ARPANET and two wireless networks (one terrestrial, the other satellite), each with characteristics that differed from the ARPANET. Before long the most prevalent networks in the system were local area networks called Ethernets.

These networks and computers and, of course, packet-switching technology all formed the underpinnings of the Internet. However, the Internet would not have become a worldwide phenomenon had it not been for three critical developments along the way. First, the National Science Foundation (NSF) in the United States embraced the DARPA technology and expanded the nascent Internet so as to allow the entire research and educational community in the United States and, in due course, much of the international community to participate. Second, a competitive telecommunications industry in the United States offered several cost-effective industry proposals for a high-speed alternative to the ARPANET. Finally, the U.S. Congress passed legislation in early 1993 that permitted NSF to open the NSFNET for commercial use as well as research and education purposes.

The Internet has clearly changed the lives of us all. Worldwide communication is now cost effective and continuously available from home and office, with access to information of all kinds readily at hand. However, a number of nontechnological issues remain. Today we are concerned with matters of privacy and security as well as with intrusions such as viruses, spam, or other offensive material. There is also the question of how best to deal with intellectual property on the Internet. These are thorny problems. Still, I believe the greatest opportunity for innovation lies in the power of the Internet to inspire new forms of creativity and to foster collaboration between individuals and organizations on a far larger scale than most of us can yet imagine.