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Looking Ahead


ARPANET originally was envisioned and funded by the Department of Defense to link the computers of a few researchers. (Over its history, the research arm of the defense agency has been known both as ARPA and as DARPA.) The first node was established at UCLA in late 1969. A month later, a second node was created at Stanford, and the network began to expand. During the late 1970s and early 1980s, the network grew to a few hundred nodes, recalls Ken Vastola. It included most major universities and a number of military research sites.

In 1985, the National Science Foundation (NSF) recognized the importance of the network to university researchers and got involved. The military portion of the Net was spun off with the ".mil" designation. By the late '80s, the network was commercialized, with ISPs making Internet e-mail service available to customers. Experiments with voice and video also began. In the early 1990s, the concept of the World Wide Web was introduced.

Backbone service providers—big phone companies such as MCI and Sprint as well as services like AOL—now have core networks that work together through cooperative agreements. Smaller companies obtain their own pipelines through contracts.

Every message is broken into little blocks of data known as packets and sent out over communications links such as phone, cable, or optical fiber lines to machines known as routers. The router reads the address on the packet and sends it on to another router that can get it to its destination. Routers around the world, for example, use a numerical address that represents the domain "," and send messages so addressed to the Troy campus. Rensselaer then has its own routers and intranetwork to forward those messages to their ultimate destination.

Unlike a letter sent through the mail or a package carried by Federal Express, no one has responsibility for the message from beginning to end, and there are no guarantees, Vastola notes. While organizing a conference, he recently sent e-mails to 12 people around the world. Most received the message within minutes. Five days later, one recipient in Houston still had not seen his.

When a router is flooded, it puts some packets into a buffer. When the buffer is full, the router begins to drop packets. Problems will get worse as exponential growth continues and people download more and larger files, Vastola says. But with increasing commercial use of the network, people will demand more efficiency and reliability, not less.


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