The Importance of Packets

When organizations first wanted to connect computers to other computers, they did the same thing that people did when they wanted to talk—they made a phone call. Since computers use digital signaling to send information, but telephone networks send everything in an analog format, these connections employed modems at each end to convert between the two kinds of signaling (see Chapter 10 for more on the difference). Companies that did a lot of data networking often leased a line from the phone company (or companies, after deregulation). This meant that they had a permanent connection—no dialing needed.

As computer networking grew in importance, the telephone method of making connections became more and more of a problem. ...

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