Circuit-Switched Networks
There are two main types of circuit-switched WANs: those based on leased lines and customer premises equipment (CPE) to manage the leased lines, and those based on ISDN, including both Basic Rate Interface (BRI) and Primary Rate Interface (PRI).
Leased Lines
Leased lines can be configured in one of two ways. The first approach uses point-to-point leased lines, as shown in Figure 7.2. In this approach, a communications link joins two nodes—and only two nodes. The good thing about this setup, of course, is that there is no contention. The two devices always have an available communications path. The disadvantage becomes pronounced when the network starts to grow, either in the number of devices or in the distance between ...
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