If you’ve ever used a telephone, tracked a package with an overnight shipper, or purchased a new car from a dealership, you’ve used a network. Of course, they weren’t computer networks-they were, respectively, the phone company’s switching network, the overnight shipper’s package-tracking network, and the car manufacturer’s distribution network. And although these networks move phone calls, packages, and cars instead of computer data, they are examples that explain the fundamental purpose of a network. The single most important purpose of any network-computer or otherwise-is to link similar items together using a set of rules that ensures reliable service.

In the telephone network’s case, the rules have to do with what happens when you dial a phone number based on how many digits you dial: If you dial seven digits, it’s a local call; eleven digits is a long-distance call. For the overnight shipper’s network, the rule is that your package … Continue reading >>>