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Introduction to Network Security

2 Firebox X Edge e-Series

Connecting to the Internet

ISPs (Internet service providers) are companies that give access to the Internet through network con-

nections. Bandwidth is the rate at which a network connection can send data: for example, 3 megabits

per second (Mbps).

A high-speed Internet connection, such as a cable modem or a DSL (Digital Subscriber Line), is known as

a broadband connection. Broadband connections are much faster than dial-up connections: the band-

width of a dial-up connection is less than .1 Mbps, while a cable modem can be 5 Mbps or more.

Typical speeds for cable modems are usually lower than the maximum speeds, because each person in a

neighborhood is a member of a LAN. Each computer in that LAN uses some of the bandwidth. Because

of this “shared-medium” system, cable modem connections can become slow when more users are on

the network.

DSL connections supply constant bandwidth, but they are usually slower than cable modem connec-

tions. Also, the bandwidth is only constant between your home or office and the DSL central office. The

DSL central office cannot supply a constant connection to a Web site or network.

Protocols

A protocol is a group of rules that allow computers to connect across a network. Protocols are the “gram-

mar” that computers use to speak to each other.

The standard protocol when you connect to the Internet is the IP (Internet Protocol). This protocol is the

usual language of computers on the Internet.

A protocol also tells how data is sent through a network. The most frequently used protocols are TCP

(Transmission Control Protocol) and UDP (User Datagram Protocol).

TCP/IP is the basic protocol used by computers that connect to the Internet. You must know some set-

tings of TCP/IP when you set up your Firebox® X Edge. For more information on TCP/IP, see “Finding your

TCP/IP properties” on page 15.

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Watchguard Firebox X5-W Guía de usuario Pagina 18