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Chapter 7: Wide-Area Networks
Core Idea
The core concept in this chapter is the establishment of networks that cover a wide geographical
area, often encompassing multiple LANs and some means to connect over a large distance
between them.
Instructor Focus
Network+ Exam Objective in this Chapter/Lesson
x Compare and contrast WAN technologies
Terminology
Make an effort to define the following terms for the designated areas. After defining these,
calling on the students for repeat definitions as you progress through the slide deck will help
them retain the terminology.
Wide-Area Network Types:
x Dedicated leased line
x Circuit-switched connection
WAN Data Classifications:
x T1
x E1
x T3
x E3
x OC1
x OC3
x OC12
WAN Technologies:
x Channel service unit/data service unit (CSU/DSU)
x Point-to-Point Protocol (PPP)
x Password Authentication Protocol (PAP)
x Challenge Handshake Authentication Protocol (CHAP)
x Microsoft Challenge Handshake Authentication Protocol (MS-CHAP)
x Satellite (WAN technology)
x Public switched telephone network (PSTN)
x Plain old telephone service (POTS)
x Telco
x Local loop
x Central office (CO)
x Tip and ring
Focus Questions
x What are three categories of wide-area network (WAN) connections?
x How are data rates measured on various WAN technologies?
x Which types of media (or wireless technologies) might be used in WAN connections?
x What are the characteristics of the following WAN technologies: dedicated leased line,
Chapter 7: Additional Network Simulator Activity
x WAN Terminology
Icebreaker Discussion
Choose one or both of the following:
1. What are the challenges in establishing a network connection between two points over a
large distance?
2. What factors have led to most network traffic going beyond the local network?
This question speaks to the need for WAN technology so that a local network is capable of
Icebreaker Activity
1. As the class to explain ways in which it would make sense for the landline telephone network
system to evolve into data networks?
There is no explicit answer here, but the main point of this exercise is to show that the level
of interconnection needed to reach from one location to another distant location is proven
to be possible because it has been done with the telephone system. The locations near
populous areas, the rights of way for the lines were already in place. The first technologies
were developed to use telephone lines.
Main Activities
1. WAN Connections and WAN Needs Evaluation
The primary focus of this chapter is to establish what the differences are between WAN and LAN
technologies. The most prominent difference is the amount of distance covered by the
technology and the access to other internetworked devices far beyond the local network.
Routing a computer to the Internet is one simple application of WAN technology, typically
The three common types of connection you should explore first are as follows:
x Dedicated leased line: High cost, no shared bandwidth, usually always on.
x Packet switched: Always on but shared resources, cost based on metrics (such as
guaranteed bandwidth)
x Circuit switched: Less expensive, periodic connections on demand. This can be
compared to a telephone call. The circuit only exists for the time that is needed for data
to be transferred, at which point, the connection is terminated.
Another important consideration in WAN is the available data rate of information transfer;
because these often aggregate local traffic, the higher bandwidth the better. The higher
The next consideration is the media used for establishing a WAN connection. The common
physical media types for WAN include the following:
x UTP: Similar to LAN technology, this is cheap but limited on distance; UTP is
common for connecting a LAN to a WAN aggregation point.
x Coax: This is common to residential connections to a WAN; same cable is used for
television and data lines.
x Electric power lines: This is useful because of the existing infrastructure; possible
due to Broadband over Power Lines (BPL), with a typical max data rate of 2.7 Mbps.
x Wireless technologies as outlined below
Quiz Questions
You can ask the following questions either in class for a group discussion or for individual practice. If
1. Briefly compare packet-switched networks to circuit-switched networks.
Packet-switched network: Typically always available but shared among users; traffic is routed
2. Briefly explain the most relevant features of a T1, T3, and E1 line.
T1: 24 channels, limit of 1.544 Mbps, originally used for voice networks, frame size of 193 bits,
3. Why are wireless technologies more expensive to implement for WAN technology than physical
connections?
Unlike LAN technology where WLANs may be cheaper, the amount of data being transmitted
and the limitation of distance make wireless both less reliable and more expensive for WAN. In
4. Briefly define the three most common types of digital subscriber line (DSL): asymmetric,
symmetric, and VDSL.
Asymmetric: Popular for residential use, data and telephone share the same line, unequal speed
