In the ARPAnet model, communications always occurred between a source (server) and a destination (client) computer. The network itself is assumed to be unreliable; any portion of the network could disappear at any moment (backhoes cutting cables are more of a threat than bombs). It was designed to require the minimum of information from the computer clients. To send a message on the network, a computer simply had to put its data in an envelope, called an Internet Protocol (IP) packet, and "address" the packets correctly. The communicating computers, not the network itself, were also given the responsibility for ensuring that the communication was accomplished. The philosophy was that every computer on the network could talk, as a peer, with any other computer.

Internet developers in the U.S., UK, and Scandinavia, responding to market pressures, began to put their IP software on every conceivable type of computer. It became the only practical method for computers from different manufactures to communicate. This was attractive to the governments and universities, which did not have policies saying that all computers must be bought from the same vendor. Everyone bought whichever computer they liked and expected the computers to work together over the network. IP was embraced as a standard which various machines regardless of operating system could communicate with one another.

At about the same time as the Internet was coming into being, Ethernet local area networks (LANs) were developed. LAN technology matured quietly until roughly 1983, when desktop workstations became available and local networking exploded. At about the same time, many companies and other organizations started building private networks using the same communications protocols as the ARPAnet: namely, IP and its relatives. It became obvious that if these networks could talk together, users on one network could communicate with those on another; everyone would benefit.

One of the most important of these newer networks was the NSFNET, commissioned by the National Science Foundation (NSF), an agency of the U.S. government. In the late 1980s, the NSF created five super computer centers at major universities. Up to this point, the world's fastest computers had been available only to weapons developers and a few researchers from very large corporations. By creating supercomputer centers, the NSF was making these resources available for any scholarly research. Only five centers were created because they were so expensive that they had to be shared. This created a communications problem: They needed a way to connect their centers together and to allow clients of these centers to access them.

At first, the NSF unsuccessfully tried to use the ARPAnet for communications. The NSF decided to build its own network, based upon the ARPAnet's IP technology. It connected the centers with 56,000-bits-per-second telephone lines (Roughly the transfer rate of two full typewritten pages per second. Slow by modern standards, but reasonably fast in the mid-1980s). Users pay for these telephone lines by the mile. One line per campus with a super computing center at the hub adds up to many miles of phone lines. Regional networks were created to save on costs. In each area of the country, schools would be connected to their nearest neighbor. Each chain was connected to a supercomputer center at one point, and the centers were connected together. With this configuration, any computer could eventually communicate with any other by forwarding the conversation through its neighbors.

This solution was successful--and, like any successful solution, a time came when it no longer worked. Sharing supercompters also allowed the connected sites to share a lot of other things not related to the centers. Suddenly these schools had a world of data and collaborators at their fingertips. The network's traffic increased until eventually the computers controlling the network, and the telephone lines connecting them, were overloaded. In 1987 a contract to manage and upgrade the network was awarded to Merit Network Inc., which ran Michigan's educational network, in partnership with IBM and MCI. The old network was upgraded with faster telephone lines (by a factor of 20) and faster computers.

The process of running out of horse power and getting bigger engines and better roads continues to this day. Unlike changes to the highway system, however, most of these changes are not noticed by the people trying to use the Internet to do real work. Like the telephone network, changes occur constantly even though they usually are transparent, if not unknown, to the user. For our purposes, the most important aspect of the NSF's network effort is that it allowed everyone to access the network. Up to that point, Internet access had been available only to researchers in computer science, government employees, and government contractors. The NSF promoted universal educational access by funding campus connections only if the campus had a plan to spread the access around. Everyone attending a four-year college could become an Internet user.

The demand keeps growing. Now that most four-year colleges are connected, secondary and primary schools are lining up to connect to the Internet. Libraries, too, are getting their links in place. Internet-literate college graduates have talked their employers into connecting corporations to the Internet. All this activity points to the continued growth, networking problems to solve, evolving technologies, and job security for networkers. The next logical stage of Internet growth will be from the home market.