|  | 2.5 | WAN Link Options
| 2.5.3 | Leased lines

Dedicated, full-time connectivity is provided by point-to-point serial links. Connections are made using the router's synchronous serial ports with typical bandwidth use of up to 2 Mbps (E1) available through the use of a CSU/DSU. Different encapsulation methods at the data link layer provide flexibility and reliability for user traffic. Dedicated lines of this type are ideal for high-volume environments with a steady-rate traffic pattern. Use of available bandwidth is a concern because you have to pay for the line to be available even when the connection is idle. Dedicated lines also are referred to as point-to-point links because their established path is permanent and fixed for each remote network reached through the carrier facilities. A point-to-point link provides a single, pre-established WAN communications path from the customer premises through a carrier network, such as a telephone company, to a remote network. The service provider reserves point-to-point links for the private use of the customer. Figure illustrates a typical point-to-point link through a WAN. Point-to-point is used for direct physical links or for virtual links consisting of multiple physical links.
| Threaded Case Study
Washington Project: Dedicated Lines
The Washington School District should use dedicated lines (T1) for its WAN core. You need to determine how many links this will involve and what kinds of equipment must be purchased (such as CSUs/DSUs).