CyberEdge Information Services: Articles & Papers: Power of P2P

The Power of P2P
Networking Background

As computers became more common and more relied on, the need for intercomputer and interpersonal communication arose quickly. Academic, military, and research facilities realized that they needed to share data. Rather than ship magnetic tape around, they wanted to wire their systems together. This led to the development of telecommunications for data sharing and local area networks (LANs).

Later, as more computers were connected, the value of these connections became more apparent. Time-sharing systems evolved to the point where they had thousands of users who could be great distances from one another. However, the connection cost was high because the links were primarily telephone lines, which were billed by the minute. Even the largest installations were only able to use a more sophisticated telephone line, the leased line, dedicated to their needs.

Telephone lines have several inherent drawbacks. First, they are analog systems, so digital signals must be modulated and demodulated by modems, which convert the signals. This slows the process and can introduce errors. Second, telephone systems are circuit-switched, meaning that the phone system essentially connects a single wire between each end of a conversation using mechanical switches that make and break the circuits. This system works fine for slow, error- forgiving analog processes, such as talking to grandma, but data is not forgiving, and making circuit-switched networks data-capable depends on a variety of kludges and workarounds.

The first public demonstration of Arpanet, a network intended to be failsafe in the event of nuclear war, was in 1972. It was designed to have multiple participants and dynamic routing. It used packet switching, which enabled routers to take a message apart, send each small part of it (the packets) by the most efficient route, and reassemble the message when it got where it was going. Although it's unlikely that Arpanet would have survived a nuclear war, it survived politics and technological progress and grew into what we now call the Internet.

In 1974, the first microcomputer, the MITS Altair, was offered as a kit for hobbyists—an event that changed the computing world forever. It was soon followed by the IMSAI, the NorthStar, and Apple. Even Radio Shack introduced the TRS-80 in the mid-70s.

By the late 1970s, PCs had infiltrated the workplace. As software matured, and especially as VisiCalc, Lotus 123, WordStar, WordPerfect, and dBase took off, PC users found that they were getting more, better work done. However, these computers were creating a lot of work for data processing managers and a large risk to corporate security. Users were installing the software they liked, and when the computer stopped, the data processing technicians had to figure out what had happened. The security risks came because data was stored on local, uncontrolled hard disks or floppies and because these floppies could be copied without anyone being aware of it.

By the mid-1980s, LANs provided one way to reassert control. LANs used a dedicated PC or mini-computer as a file server. Essentially, this gave PCs much bigger hard disks and made it much easier to share information. Networking also provided a measure of control.

The first LANs, using mainframes and mini-computers as hubs in a client– server network, tied all the PCs to a server in a wheel-and-spoke arrangement, with the server storing program and data files and the PCs doing the processing. The downside of client–server networks was the expense. Servers were special-purpose machines that cost more than desktop PCs, software to run the network was expensive, and setting up and managing a LAN took a lot of time. This made LANs impractical for small offices, where aside from the capital expense, the expertise to set up and maintain the network was often lacking.

In the modern computing environment, connecting computers in a variety of configurations is common. It isn't unusual to find LANs, WANs, Intranets, and the Internet interconnected in a vast computing fabric that leverages local and remote resources. P2P is just the latest piece of this computing puzzle, helping to fill some of the gaps.

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