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Chapter 16: Wide Area Networks (WANS)
Instructor:
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2. Chapter 16 Objectives
The Following CompTIA Network+ Exam Objectives Are Covered in This Chapter:
1.4 Explain the characteristics and benefits of various WAN technologies
• Fiber
o SONET
o DWDM
o CWDM
• Frame relay
• Satellite
• Broadband cable
• DSL/ADSL
• ISDN
• ATM
• PPP/Multilink PPP
• MPLS 2

3. Chapter 16 Objectives (Cont)
• GSM/CDMA
o LTE/4G
o HSPA+
o 3G
o Edge
• Dialup
• WiMAX
• Metro-Ethernet
• Leased lines
o T-1
o T-3
o E-1
o E-3
o OC3
o OC12
• Circuit switch vs packet switch 3

4. Chapter 16 Objectives (Cont)
1.7 Differentiate between network infrastructure implementations
• WAN
• MAN
• LAN
4.8 Given a scenario, troubleshoot and resolve common WAN issues
• Loss of internet connectivity
• Interface errors
• Split horizon
• DNS issues
• Interference
• Router configurations
• Customer premise equipment
o Smart jack/NIU
o Demarc
o Loopback
o CSU/DSU
o Copper line drivers/repeaters
• Company security policy
o Throttling
o Blocking
o Fair access policy/utilization limits
• Satellite issues
o Latency 4

5. Chapter 16 Objectives (Cont)
2.2 Given a scenario, analyze metrics and reports from monitoring and tracking
• Link status
• Interface monitoring
o Errors
o Utilization
o Discards
o Packet drops
o Interface resets
o Speed and duplex 5

6. What’s a WAN?
WANs are communications networks that cover broad geographic areas that still frequently use phone companies (service providers) along with their circuit-switched networks to connect LANs together.
WAN protocols and technologies all occupy the lower three layers of the OSI model
Physical layer
Data Link layer
Network layer (sometimes) 6

7. Defining WAN Terms Customer premises equipment (CPE) CSU/DSU
Demarcation point
Local loop
Central office (CO)
Toll network / Provider Network
Local loop
Smart
Jack/NIU
CPE
Provider Network
Demarc CO
ISP can perform a loopback test from CO to NIU 7

8. The Public Switched Telephone Network (PSTN)
The portion of the PSTN running from your house to the rest of the world.
Known as the plain old telephone service (POTS).
The PSTN is a popular method for connecting remote users to a local network because of its simplicity, low cost, and easy installation.
Connecting to PSTN via ISDN, DSL, a cable modem, or even your cellular service is becoming popular. 8

9. Asynchronous serial, ISDN
WAN Connection Types
There are various types of WAN connections you’ll find on the market today.
Synchronous serial
Dedicated
Asynchronous serial, ISDN
Telephone
company
Circuit-switched
Synchronous serial
Service
provider
Packet-switched 9

10. WAN Technologies WAN Connection Types Bandwidth or Speed
Leased lines
Circuit switching
Packet switching
Bandwidth or Speed
T-Series Connections 10

11. Transmission Media Wired Connections
Synchronous Optical Network (SONET), and the international equivalent of SONET is known as Synchronous Digital Hierarchy (SDH).
SONET defines a base data rate or throughput
This rate are known as optical carrier (OC) levels 11

12. Dense Wavelength Division Multiplexing
Multiplexes several optical carriers on a single optical fiber by using different wavelengths
The system consists of the following:
DWDM terminal multiplexer
Intermediate line repeater (every 80–100 km)
Intermediate terminal multiplexer (remote amplification site)
DWDM terminal de-multiplexer 12

13. Passive Optical Network
A point-to-multipoint technology with a single fiber strand used for multiple premises (typically 16–28)
Consists of an optical line termination (OLT) at the telco’s office and a number of optical network units (ONUs) near end users.
These systems typically have downlink speeds of 155 to 655 Mbps and uplink bursts to 155 Mbps. 13

14. Wireless Technologies
Bluetooth
Microwave Radio Relay
Communications Satellite (comsat)
Aircraft Terminal
Transportable Terminal
Surfaced Submarine Terminal
Semi-Fixed Terminal
Fixed Terminal
Ship Terminal 14

15. Broadband Services
Dedicated broadband services include transmissions over media in a broad range of frequencies.
DSL - digital subscriber line services are broadband in the sense that digital information is sent over a high-bandwidth channel above the baseband voice channel on a single pair of wires.
Ethernet digital signals sent over a cable modem from your local cable service provider are a competitor for DSL service.
DSL and cable Internet services do indeed have a lot in common, they still have some basic, essential differences that are really important for you to understand
Speed
Security
Popularity
Customer satisfaction 15

16. Broadband Services
A connection can terminate from modems to either a PC directly or to a router. 16

17. DSL Technology and xDSL
High bit-rate digital subscriber line (HDSL)
Symmetric digital subscriber line (SDSL)
Very high data-rate digital subscriber line (VDSL)
Asymmetric digital subscriber line (ADSL)
Cable Modem
Headend
Distribution network
Data Over Cable Service Interface Specification (DOCSIS) 17

18. Wireless WAN Technologies
Cellular WAN
HSPA+
WiMAX
LTE 18

19. WAN Protocols Integrated Services Digital Network (ISDN)
Frame Relay Technology
Before Frame Relay
Frame Relay Implementation 19

20. WAN Protocols – Frame Relay
Frame Relay Technology
Access rate
Committed Information Rate (CIR)
Virtual Circuits
Frame Relay operates using virtual circuits as opposed to the actual physical circuits leased lines use.
Virtual Circuits that stay connected continuously are known as Permanent Virtual Circuits (PVCs)
Data Link Connection Identifiers (DLCIs)
Frame Relay PVCs are identified to DTE end devices by Data Link Connection Identifiers (DLCIs). 20

21. WAN Protocols Asynchronous Transfer Mode (ATM)
Asynchronous Transfer Mode (ATM), not to be confused with automated teller machines, first emerged in the early 1990s.
ATM was designed to be a high-speed communications protocol that does not depend on any specific LAN topology.
ATM uses a high-speed cell-switching technology 21

22. PPP stack Figure 16.8

23. PPP session establishment Figure 16.9

24. Chapter 16 A typical wide area network Figure 16.10 Local loop Smart
Jack/NIU
CPE
Provider Network
You can perform a loopback test from
your router to the CSU/DSU
Demarc CO
ISP can perform a loopback test from CO to NIU

25. Summary Summary Exam Essentials Section Written Labs Review Questions25