As we learned earlier in this course, the number of point-to-point lines in a full mesh network increases sharply with the number of nodes. Switched services provide more flexibility in connecting WAN nodes. Dial-up or dedicated connections are still necessary to reach the switched network; however, after the switched network is accessed, you have any-to-any connectivity.

In addition, private lines are engineered to meet peak traffic rates. In other words, a network designer must buy enough point-to-point bandwidth to carry the network's highest expected level of traffic. During nonpeak times, however, unused transmission capacity goes to waste. Switched services can provide variable capacity, at rates that vary according to the bandwidth actually used.

Thus, the emphasis in wide area networking is shifting from dedicated networks to switched alternatives. Public switched networks, such as frame relay and asynchronous transfer mode (ATM), are highly reliable, fast, and efficient. This lesson introduces these services, which are the most popular switched WAN technologies used today. We will also introduce the structure of the Internet, which is becoming a popular wide area link for businesses of all sizes.

   Objectives

At the end of this lesson you will be able to:

Key Point
Switched service provides greater connectivity options.

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