Networking Chapter 12 Homework which are networks that connect two or more geographically

Network+ Guide to Networks, 8th Edition 12-1

Chapter 12

Wide Area Networks

At a Glance

Instructor’s Manual Table of Contents

• Overview

• Objectives

• Teaching Tips

• Quick Quizzes

• Class Discussion Topics

• Additional Projects

• Additional Resources

• Key Terms

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Lecture Notes

Overview

This chapter focuses on WANs (wide area networks), which are networks that connect two or

more geographically distinct LANs. WANs are significant concerns for organizations attempting

to meet the needs of telecommuting workers, global business partners, and Internet-based

commerce. This chapter discusses WAN topologies and various technologies used by WANs. It

also notes the potential pitfalls in establishing and maintaining WAN connections.

Chapter Objectives

After reading this chapter and completing the exercises, the student will be able to:

• Identify the fundamental elements of WAN service options

• Compare and contrast Layer 1 WAN technologies

• Compare and contrast Layer 2 WAN technologies

• Explain the most common wireless WAN technologies

Teaching Tips

WAN Essentials

2. Discuss the major characteristics of WANs including how a WAN differs from a LAN.

3. Define and explain the term NSPs (network service providers).

4. Define the term, dedicated line and explain the advantages it provides.

Data Transfer Methods

2. Use Figure 12-2 to discuss the difference between Data Terminal Equipment (DTE) and

Data Communications Equipment (DCE).

3. Discuss the primary categories of WAN connections:

a. dedicated line

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b. virtual circuit

c. PVC (permanent virtual circuit)

d. SVC (switched virtual circuit)

5. Discuss the differences between circuit-switched and packet-switched technologies. Point

6. Use Table 12-1 to provide an overview of wired WAN technologies.

Troubleshooting an Internet Connection

1. Explain the importance of understanding ISP equipment vs. equipment belonging to the

subscriber (known as CPE or customer premise equipment).

2. Discuss the following equipment:

3. Discuss some common issue to look for on customer equipment:

a. interface error

b. DNS issues

c. router misconfiguration

d. interference

Layer 1 WAN Technologies

1. Discuss examples of Layer 1 standards such as DSL, ISDN, SONET, T-carrier links.

2. Point out that a significant difference between the Layer 1 technologies is whether the

connection is shared among many customers or dedicated to one customer.

3. Discuss the following:

a. broadband

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b. DIA (dedicated internet access)

PSTN (Public Switched Telephone Network)

1. Define and describe a PSTN. Mention that the name POTS also refers to a PSTN.

2. Note how PSTNs originally carried analog traffic and compare it to today’s methods.

3. Use Figure 12-6 to illustrate the local loop portion for dial-up WAN access.

4. Discuss the three examples of PSTN-based network technologies. Point out that these are

5. Briefly cover the Legacy Networking: Dial-Up section on page 691 of the text.

7. Define and explain the two types of ISDN channels on which connections are based:

8. Describe a BRI (Basic Rate Interface).

10. Use Figure 12-9 to illustrate a BRI link.

11. Describe a PRI (Primary Rate Interface).

12. Compare and contrast PRI and BRI connections.

13. Use Figure 12-10 to illustrate a PRI link.

DSL (Digital Subscriber Line)

1. Define and describe characteristics of a DSL (digital subscriber line).

2. Define the term xDSL. Describe the better-known DSL varieties:

a. ADSL (asymmetric DSL)

4. Explain how an ADSL connection flows from a home computer, through the local loop,

5. Define the term DSL modem.

6. Use Figure 12-12 to illustrate a DSL modem.

7. Explain what a DSLAM (DSL access multiplexer) is and what it does.

8. Review DSL installation costs.

Cable Broadband

1. Introduce broadband cable. Mention that it is also known as cable modem access.

2. Describe the transmission media used by broadband cable.

4. Describe the infrastructure required for broadband cable to operate. Use Figure 12-13 to

illustrate the infrastructure of a cable system.

6. Use Figure 12-14 to illustrate a cable modem.

8. Mention that cable broadband access continues to service the majority of residential

customers, whereas DSL is more popular among business customers.

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Metro (Metropolitan Ethernet)

1. Discuss the growing trend of Metro Ethernet, also known as Carrier Ethernet.

2. Explain that Carrier-Ethernet Transport (CET) is an Ethernet-based transport solution

4. Discuss the many advantages of Metro Ethernet, including:

a) streamlined connections

b) cost efficiency

c) scalability

d) familiarity

e) hardware

Quick Quiz 1

1. True or False: A WAN link is a connection between one WAN site and another site.

2. What is a customer’s endpoint device on a WAN is called?

3. True or False: PVCs are dedicated, individual links.

4. True or False: Broadband cable relies on the PSTN for transmission medium.

5. Which of the following types of communication occurs when the downstream throughput

is higher than the upstream throughput?

a. DSU

b. CSU

c. Symmetrical

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d. Asymmetrical

T-Carriers

1. Introduce T-carrier technology. Point out that T-carriers provide a dedicated logical

circuit that is used by only one customer.

2. Describe the T-carrier transmission medium.

3. Discuss the different types of T-carrier lines:

4. Use Table 12-3 to illustrate the various T-carrier specifications.

5. Describe a T1 circuit’s operation and throughput.

6. Describe a T3 circuit’s operation and throughput.

7. Describe common uses for T1 and T3 lines.

8. Define a fractional T1 lease and its advantages.

9. Explain that T1s are often used to support voice services. Discuss the two primary ways it

11. Define and explain the functions of a smart jack.

12. Use Figure 12-18 to illustrate a T1 smart jack.

13. Define and explain the functions of CSUs (channel service units) and DSUs (data service

units).

15. Explain that a multiplexer combines multiple signals from a LAN for transport over the

16. Use Figure 12-20 to illustrate how a router with an integrated CSU/DSU can be used to

connect a LAN with a T1 WAN link.

SONET (Synchronous Optical Network)

1. Describe the four key strengths of SONET.

2. Explain the interoperability advantage of SONET.

3. Point out that SONET is known internationally as SDH (Synchronous Digital Hierarchy).

5. Use Figure 12-21 to discuss SONET tributaries and transmission.

8. Define the term OC (Optical Carrier) level and explain its relation in determining the data

rate of a particular SONET ring.

9. Use Table 12-4 to list the OC levels and their maximum throughput.

10. Explain the best use of SONET.

Layer 2 WAN Technologies

1. Explain that there are some Layer 2 technologies that traverse the ISP’s network in order

to connect two or more LANs across a WAN connection.

Frame Relay

1. Define and describe frame relay. Point out that frame relay can be used as the Data Link

2. Explain why frame relay is considered a connection-oriented protocol.

4. Define the term CIR (committed information rate).

5. Describe how the lease works for a PVC circuit.

6. Discuss frame relay lease advantages.

ATM (Asynchronous Transfer Mode)

1. Point out where ATM protocols operate in the OSI model.

2. Explain that with ATM, asynchronous refers to a communications method in which

4. Explain what sets ATM apart from Ethernet on a LAN and frame relay on a WAN.

6. Describe a drawback of a smaller packet size and explain how the drawback is overcome

by cell efficiency.

8. Explain how ATM guarantees specific QoS (quality of service).

9. Point out the cost disadvantage inherent with ATM.

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MPLS (Multiprotocol Label Switching)

2. Discuss the formation of an MPLS shim within a frame. Use Figure 12-26 in your

discussion.

Wireless WANs

1. Introduce and describe wireless WANs. Point out that wireless WANs are designed for

high-throughput, long-distance digital data exchange.

Cellular

1. Define and describe cellular networks.

3. Discuss the two competing voice technologies:

4. Explain the architecture of cellular networks using Figure 12-27.

5. Explain that in order to qualify for the CompTIA Network+ certification, students will

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Satellite

1. Introduce satellite Internet access by explaining where it is best utilized.

2. Define and describe geosynchronous earth orbit (GEO).

3. Use Figure 12-28 to illustrate satellite communication.

5. Describe satellite frequencies.

6. Use Table 12-5 is discuss satellite frequency bands.

7. Point out that satellite services are typically asymmetrical and bandwidth is shared among

many subscribers Discuss they typical downlink and uplink rates that can be expected.

8. Discuss the drawbacks of satellite services.

Quick Quiz 2

1. Which of the following is used to convert T-Carrier frames into frames the LAN can

interpret and vice versa?

a. smart jack

b. CSU

c. DSU

d. terminal adapter

2. True or False: An advantage of leasing a dedicated service over leasing a frame relay

circuit is that you pay for only the amount of bandwidth required.

3. Which of the following attributes sets ATM apart from Ethernet and Frame Relay?

e. Fixed packet size

f. Security

g. Wiring

h. Throughput

4. True or False: An advantage of SONET is its fault tolerance.

5. ____ orbiting satellites are the type used by the most popular satellite data service

providers.

Class Discussion Topics

1. Take a class poll to determine what kind of Internet access students have at home.

2. Discuss the security implication of always-on technologies like DSL in remote home

offices. What concerns are there? Are they justified? Is the technology worth the security

risks, if any?

Additional Projects

1. Have students compare cable broadband and DSL services in their residential areas. Each

student should write a report summarizing his or her findings.

2. Have students research satellite Internet access. Students may select a vendor supplying

the service, a manufacturer, or a technology. Each student should write a report

summarizing his or her findings.

Additional Resources

1. Local Loop

Key Terms

For definitions of key terms, see the Glossary near the end of the book.

➢ 4G

➢ Carrier Ethernet

➢ CDMA (Code Division Multiple Access)

➢ cell

➢ CET (Carrier-Ethernet Transport)

➢ circuit-switched

➢ frame relay

➢ GSM (Global System for Mobile Communications)

➢ HFC (hybrid fiber coaxial)

➢ HSPA+ (High Speed Packet Access Plus)

➢ ISDN (Integrated Services Digital Network)

➢ OC-3

➢ OC-12

➢ packet-switched

➢ PRI (Primary Rate Interface)

➢ PSTN (public switched telephone network)

➢ synchronous

➢ T1

➢ T3

➢ T-carrier

➢ TDMA (time division multiple access)