Part III: Wide-Area Networks

Chapter 9 Point-to-Point Leased Line Implementation

Chapter 10 ISDN and Dial-on-Demand Routing

Chapter 11 Frame Relay

This chapter covers the following subjects:

■Review of WAN Basics

■Data-Link Protocols for Point-to-Point Leased Lines

■Authentication Over WAN Links

C H A P T E R 9

Point-to-Point Leased Line

Implementation

This chapter covers the details of point-to-point WAN links. It starts with a review of the basics and provides background information that gives you the right perspective for Chapters 10, “ISDN and Dial-on-Demand Routing,” and 11, “Frame Relay.” This chapter also includes deeper coverage of HDLC and PPP, plus CHAP configuration.

Perhaps you are using both this book and CCNA INTRO Exam Certification Guide to prepare to pass the CCNA exam—the single-exam method of getting your CCNA certification. If you are using the reading plan suggested in the Introduction to both books, be aware that this chapter is the first WAN chapter in this book. After this chapter, you should read Chapters 10 and 11 before moving on to the final chapters in each book. Refer to this book’s Introduction for details.

“Do I Know This Already?” Quiz

The purpose of the “Do I Know This Already?” quiz is to help you decide if you need to read the entire chapter. If you intend to read the entire chapter, you do not necessarily need to answer these questions now.

The eight-question quiz, derived from the major sections in the “Foundation Topics” section, helps you determine how to spend your limited study time.

Table 9-1 outlines the major topics discussed in this chapter and the “Do I Know This Already?” quiz questions that correspond to those topics.

Table 9-1 Do I Know This Already?” Foundation Topics Section-to-Question Mapping

302 Chapter 9: Point-to-Point Leased Line Implementation

CAUTION The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you don’t know the answer to a question or you’re only partially sure of the answer, you should mark this question as wrong for purposes of the self-assessment. Giving yourself credit for an answer you guess correctly skews your self-assessment results and might give you a false sense of security.

1.Which of the following types of WAN connections allow the direct use of PPP as the encapsulation type on the interface?

a.Circuit switching

b.Packet switching

c.Leased lines

d.LAN switching

2.Which of the following commands are required on the router connected to a DTE cable to make the serial link between two routers work when the two routers are connected in a lab using a DTE and DCE cable and no CSU/DSUs?

a.clock rate 56000

b.clockrate 56000

c.bandwidth 56000

d.band width 56000

e.None of the above

3.Which of the following commands make a serial interface revert to the default data-link protocol if it is currently configured with PPP?

a.wan default

b.default

c.encapsulation ppp

d.encapsulation frame-relay

e.encapsulation hdlc

f.no encapsulation

g.no encapsulation ppp

h.no encapsulation hdlc

i.no encapsulation frame-relay

“Do I Know This Already?” Quiz 303

4.Which of the following authentication protocols authenticates a device on the other end of a link without sending any password information in clear text?

a.MD5

b.PAP

c.CHAP

d.DES

e.Triple DES

5.Imagine that two routers, R1 and R2, have a leased line between them. Each router had its configuration erased and was then reloaded. R1 was then configured with the following commands:

interface s0/0 encapsulation ppp

ppp authentication chap

Which of the following configuration commands can complete the configuration on R1 so that CHAP can work correctly? Assume that R2 has been configured correctly and that the password is fred.

a.No other configuration is needed.

b.ppp chap (global command)

c.user R1 password fred

d.user R2 password fred

e.ppp chap password fred

6.Which of the following is a reason to avoid using link compression?

a.Reduction in the cumulative number of bytes sent on a link

b.Reduction in queuing delay

c.Reduction in available router CPU cycles for other tasks

d.Reduction in serialization delay

304Chapter 9: Point-to-Point Leased Line Implementation

7.Which of the following does PPP use as part of how it notices when a link has been looped, causing packets sent by a router to be returned to that router?

a.LQM

b.Magic number

c.Type field

d.MD5 hash

8.Which of the following are protocols defined as part of PPP?

a.HDLC

b.LCP

c.LAPD

d.IPCP

The answers to the “Do I Know This Already?” quiz appear in Appendix A. The suggested choices for your next step are as follows:

■6 or less overall score—Read the entire chapter. This includes the “Foundation Topics,” “Foundation Summary,” and “Q&A” sections.

■7 or 8 overall score—If you want more review on these topics, skip to the “Foundation Summary” section and then go to the “Q&A” section. Otherwise, move to the next chapter.