TCP / IP For Dummies
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Protocols and standards are what make networks work together. Protocols make it possible for the various components of a network to communicate with each other. Standards also make it possible for network components manufactured by different companies to work together.

A protocol is a set of rules that enables effective communications to occur. You encounter protocols every day.

For example, when you pay for groceries with a debit card, the clerk first tells you how much the groceries cost. You then swipe your debit card in the card reader, punch in your security code, indicate whether you want cash back, enter the amount of the cash back if you so indicated, then verify the total amount. Assuming the amount is authorized, the machine prints out your receipt.

Exchanges such as using debit cards follow the same rules every time they happen.

Computer networks depend upon many different types of rigidly defined protocols in order to work. Network cards must know how to talk to other network cards in order to exchange information, operating systems must know how to talk to network cards in order to send and receive data on the network, and application programs must know how to talk to operating systems in order to know how to retrieve a file from a network server.

Protocols come in many different types. At the lowest level, protocols define exactly what type of electrical signal represents a one and what type of signal represents a zero. At the highest level, protocols allow a computer user in the United States to send an e-mail to another computer user in New Zealand.

Various protocols tend to be used together in matched sets called protocol suites. The two most popular protocol suites for networking are TCP/IP and Ethernet. TCP/IP was originally developed for Unix networks and is the protocol of the Internet and most local-area networks. Ethernet is a low-level protocol that spells out the electrical characteristics of the network hardware used by most local-area networks.

A third important protocol is IPX/SPX, which is an alternative to TCP/IP that was originally developed for NetWare networks. In the early days of networking, IPX/SPX was widely used in local area networks, but TCP/IP is now the preferred protocol.

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