As mentioned in the introduction, you have two choices for review questions. The questions that follow give you a bigger challenge than the exam itself by using an open-ended question format. By reviewing now with this more difficult question format, you can exercise your memory better and prove your conceptual and factual knowledge of this chapter. The answers to these questions are found in Appendix A.
For more practice with exam-like question formats, including questions using a router simulator and multiple-choice questions, use the exam engine on the CD.
1. Are DLCI addresses defined by a Layer 2 or Layer 3 protocol?
2. What OSI layer typically encapsulates using both a header and a trailer?
3. Define the terms DCE and DTE in the context of the physical layer and a point-to-point serial link.
4. Which layer or layers of OSI are most closely related to the functions of Frame Relay? Why?
5. What is the name of the field that identifies, or addresses, a Frame Relay virtual circuit?
6. True or False: "A leased line between two routers provides a constant amount of bandwidth—never more and never less." Defend your answer.
7. True or False: "Frame Relay VCs provide a constant amount of bandwidth between two devices, typically routers—never more and never less." Defend your answer.
8. Explain how many DS0 channels fit into a T1, and why the total does not add up to the purported speed of a T1, which is 1.544 Mbps.
10. Imagine a drawing with two routers, each connected to an external CSU/DSU, which each is connected with a four-wire circuit, as seen in this chapter. Describe the role of the devices in relation to clocking and synchronization.
11. Imagine a drawing with two routers, each connected to an external CSU/DSU, which each is connected with a four-wire circuit, as seen in this chapter. List the words behind the acronyms DTE and DCE, and describe which devices in this imagined network are DTE and which are DCE.
12. Imagine a drawing with two routers, each connected to a Frame Relay switch over a local access link. Describe which devices in this imagined network are Frame Relay DTEs and which are Frame Relay DCEs.
13. Do HDLC and PPP, as implemented by Cisco routers, support protocol type fields and error detection? Explain your answer.
14. Imagine a point-to-point leased line between two routers, with PPP in use. What are the names of the protocols inside PPP that would be used on this link? What are their main functions?
15. What are some of the main similarities between Frame Relay and ATM?
16. Compare and contrast ATM and SONET in terms of the OSI model.
17. Besides HDLC and PPP, list the other four serial point-to-point data-link protocols covered in this chapter.
18. List the speeds of a T1 line, E1, OC-3, and OC-12.
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