Leased-line WANs—also known as serial links—require much less thought than many other topics, at least to the depth required for the CCENT and CCNA exams. That simplicity allows the Cisco exams to discuss leased lines briefly for the ICND1 exam, while using leased lines as part of larger discussions of IP routing.
This chapter finally takes the discussion of leased-line WANs deeper than has been discussed so far. This chapter briefly repeats the leased line concepts from the ICND1 book, to lay a foundation to discuss other concepts. More important, this chapter looks at the configuration, verification, and troubleshooting steps for leased lines that use the familiar High-level Data Link Control (