This document appears to be a lecture on wide area networks (WAN) and high speed networks given by Dr. Raad Al Selwi at Taiz University. The lecture covers an overview of computer networks, an introduction to WAN technologies, and discusses WAN concepts like leased lines, T-carrier lines, xDSL, ISDN, Frame Relay, ATM, cable modem networks, SONET/SDH, quality of service, congestion control, HDLC, PPP, last mile technologies, and both older and emerging WAN technologies. The document includes outlines, references, and section titles to structure the lecture content.

1. Taiz University
Networks Department
Dr. Raad Al Selwi
Taiz 2022
1
WAN and High Speed Networks

2. Dr. Raad Al Selwi
Taiz 2022
Outlines
 Overview of Computer Network
 Introduction to WAN
 Leased lines, T-Carrier lines, xDSL
 WAN technologies:
 ISDN network
 X. 25 network
 Frame Relay network
 ATM network
 Cable TV modem network
 SONET/SDH networks
 Quality of Service
 Congestion Control
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3. Dr. Raad Al Selwi
Taiz 2022
References
 Data communications and computer networks: for computer
scientists and engineers/ Michael Duck and Richard Read.––
2nd ed. Pearson Education Limited. 2003.
 Data and Computer Communications. William Stallings. Eighth
Edition. Pearson Prentice Hall. 2007.
 Data Communications and Networking. F I F T H E D I T I O N.
Behrouz A. Forouzan. McGraw-Hill. 2013.
 John Rullan, “WAN Technologies CCNA 4 Labs and Study Guide
(Cisco Networking Academy)”, Cisco Press, Aug 30, 2006.
 Walter Goralski - Frame Relay for High Speed Networks-J.
Wiley & Sons (1999).
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4. WAN and High Speed Networks
Dr. Raad Al Selwi Lecture 1
Taiz 2022
Introduction to WAN
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5. Dr. Raad Al Selwi Lecture 1
Taiz 2022
Outlines
 WAN definition
 Need for WANs
 WAN basics
 Toll Network
 Types of WAN circuits
 WAN Link Options
 Selecting a WAN connection
 WAN devices
 WAN and OSI reference model
 HDLC protocol
 PPP protocol
 Last Mile and Long Range WAN technologies
 WAN properties
 Older and emerging WAN technologies
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6. Dr. Raad Al Selwi Lecture 1
Taiz 2022
Overview of Computer network
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 Introduction to Data communication and networking
 Networks
 Internet
 Network reference models
 Transmission Media
 Network topology
 Network components
 Data Encoding
 LAN technologies

7. Dr. Raad Al Selwi Lecture 1
Taiz 2022
WAN definition
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 A WAN is a data communications network that covers a relatively broad geographic
area and that often uses transmission facilities provided by common carriers, such as
telephone companies. WAN technologies generally function at the lower three layers of
the OSI reference model: the physical layer, the data link layer, and the network layer.

8. Dr. Raad Al Selwi Lecture 1
Taiz 2022
Need for WANs
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9. Dr. Raad Al Selwi Lecture 1
Taiz 2022
Introduction to WAN
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10. Dr. Raad Al Selwi Lecture 1
Taiz 2022
Basic Terms
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Time Division Multiplexing - TDM

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Taiz 2022
Basic Terms
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Taiz 2022
Basic Terms
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Taiz 2022
Toll Network
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Taiz 2022
Types of WAN circuits
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Taiz 2022
WAN Link Options
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Taiz 2022
WAN Link Options
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Taiz 2022
WAN Link Options
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Taiz 2022
WAN Link Options
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Taiz 2022
WAN Link Options
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Taiz 2022
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Taiz 2022
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Taiz 2022
WAN devices
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Taiz 2022
WAN devices
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 WANs use numerous types of devices that are
specific to WAN environments. WAN switches,
access servers, modems, CSU/DSUs, and ISDN
terminal adapters are discussed in the
following slides.
 Other devices found in WAN environments
that are used in WAN implementations
include routers, ATM switches, and
multiplexers.

24. Dr. Raad Al Selwi Lecture 1
Taiz 2022
WAN Switch
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 A WAN switch is a multiport internetworking device used in carrier
networks.
 These devices typically switch such traffic as Frame Relay, X.25, and SMDS,
and operate at the data link layer of the OSI reference model.

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Taiz 2022
Access Server
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 An access server acts as a concentration point for dial-in and dial-
out connections.

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Taiz 2022
Modem
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 A modem is a device that interprets digital and analog signals, enabling data
to be transmitted over voice-grade telephone lines.
 At the source, digital signals are converted to a form suitable for transmission
over analog communication facilities.
 At the destination, these analog signals are returned to their digital form.

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Taiz 2022
CSU/DSU
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 A channel service unit/digital service unit (CSU/DSU) is a digital-interface
device used to connect a router to a digital circuit like a T1.
 The CSU/DSU also provides signal timing for communication between these
devices.

28. Dr. Raad Al Selwi Lecture 1
Taiz 2022
ISDN Terminal Adapter
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o An ISDN terminal adapter is a device used to connect ISDN Basic Rate
Interface (BRI) connections to other interfaces, such as EIA/TIA-232 on a
router.
o A terminal adapter is essentially an ISDN modem, although it is called a
terminal adapter because it does not actually convert analog to digital signals.

29. Dr. Raad Al Selwi Lecture 1
Taiz 2022
WAN and OSI reference model
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Taiz 2022
WAN physical layer
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WAN physical layer
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WAN physical layer
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Taiz 2022
WAN physical layer
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WAN data link protocol (Encapsulation)
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Taiz 2022
HDLC frame format
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Taiz 2022
An overview of PPP protocol
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Taiz 2022
Layering PPP elements
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PPP LCP configuration options
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Last Mile and Long Range WAN technologies
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Taiz 2022
Last Mile and Long Range WAN technologies
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WAN properties Older WAN technologies
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Taiz 2022
Older WAN technologies
POTS, PSTN
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Taiz 2022
Emerging WAN technologies
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