CWNA Guide to Wireless LANs, Second Edition
Chapter 6
Planning and Deploying a Wireless LAN
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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CWNA Guide to Wireless LANs, Second Edition
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Lecture Notes
Overview
A computer network is essentially hidden from the eyes of most users; they rarely see
servers, switches, routers, or even the cabling infrastructure that supports the network.
To a computer professional, nothing is farther from the truth. All computer networks,
both wired and wireless, require extensive planning and preparation if they are to
seamlessly mesh with an enterprise’s existing network infrastructure. And once the
preparation is done, the actual work of installing and configuring the network can take
an extended period of time. Yet the work does not end when the last device is
connected. Ongoing support and training is required to assist users and troubleshoot any
problems that may occur.
In this chapter, students will learn how to plan for and deploy a wireless LAN. This
process involves four basic steps: planning for the network, designing the WLAN,
deploying the wireless network, and providing user training and support.
Chapter Objectives




Explain the steps for planning a wireless network
Tell how to design a wireless LAN
Describe the steps in deploying a wireless network
Explain the ways in which to provide user support
Teaching Tips
Planning for a Wireless Network
1. Provide an overview of the basic planning steps for planning a wireless network.
Explain that, although some of the planning steps are similar to planning a wired
network, many of the steps are significantly different.
Assessing Needs
1. Provide an overview of the process of assessing needs, mentioning that it involves
understanding the need for mobility, examining the business as a whole, and calculating
the potential return on investment.
The Need for Mobility
1. Explain that many industry experts believe that the greatest opportunity for businessprocess improvement at the beginning of the 21st century lies with extending network
access to employees who are often away from their desks through wireless networks
and VoIP.
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2. Discuss the two major changes in the business world that have occurred over the last 15
years. Stress that organizations are now “flatter” than they used to be, and teamwork is
essential in this type of environment.
3. Explain why the combination of the two major changes can actually decrease business
productivity. Stress that a “mobile office” organization is needed.
Teaching
Tip
According to a 20-year study of 1,800 corporate managers, the average
professional spends as much as 48.8 hours a month in meetings, yet as much as
50 percent of meeting time is wasted. This is because of the unavailability of
proper information to make decisions during the meetings, or meetings getting
delayed as participants try to quickly gather the data they need. When accounting
for the salaries of everyone attending, poorly run meetings cost nearly $100
million a year.
4. Discuss the reasons why WLANs are a good solution to the mobility issue in business
environments. Explain how WLANs enable a larger productivity zone and help
facilitate more productive meetings. Mention that WLANs have been shown to add 1 to
2 hours of productive time per day per worker.
Teaching
Tip
According to a study conducted by NOP World–Technology, wireless LANs
enable users to be connected to network resources 1.75 additional hours per day,
which translates into the average user being 27 percent more productive. Based
on an average IT salary of $64,000, the annual productivity improvement per
user is estimated at $14,000.
5. Mention that WLANs are too often considered simply optional add-ons to a network.
Examining the Business Entity
1. Explain that the next step in assessing the need for WLANs is to determine whether
there is a business case for incorporating WLANs into an organization’s infrastructure.
Using the list on page 198 of the text as a guide, discuss the questions that must be
considered.
2. Stress that obtaining a firm conceptual grip on the organization as a whole and its
current status will reveal if an investment in wireless technology is a wise step.
Reviewing the Current Network
1. Using the list on the bottom of page 198 of the text as a guide, discuss the questions that
should be posed when examining how an organization uses its current network. Stress
that examining the current status of the network, especially the applications that run on
the network and the number of users, can reveal a great deal of information.
2. Explain that if the current network is weak and cannot support the current business
functions adequately, then the first step must be to strengthen it instead of adding a new
technology.
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3. Explain that the review process offers an excellent opportunity to document the network
in detail. Using the list on page 199 of the text as a guide, discuss the types of
information that should be document. Illustrate an example with Table 6-1. Also
illustrate an example of a network diagram with Figure 6-1.
Determining Benefits
1. Provide an overview of the process of determining the benefits network expansion.
Introduce the concepts of hard benefits and soft benefits.
Hard Benefits
1. Define the term hard benefits. Explain that for wireless LANs the hard benefits can be
easily measured in the decreased cost of installation.
2. Mention that using wireless technology for a MAN or WAN can result in even higher
savings than it can for a WLAN. Discuss the reasons for these cost savings over wired
solutions.
Teaching
Tip
The incremental cost required to add additional users to an existing WLAN is
also very low. Average cost per user drops dramatically as more people are
added to WLAN.
Soft Benefits
1. Explain that soft benefits are difficult, if not impossible, to quantify accurately. Mention
that many studies show that soft benefits actually have the greatest impact on
organization.
Teaching
Tip
Soft benefits may vary substantially depending on the size of the organization
and the functions it performs.
2. Using the list on pages 201 and 202 of the text as a guide, discuss some examples of
soft benefits associated with implementing a wireless network.
Teaching
Tip
According to NOP-World Technology, 87 percent of end users said that a
WLAN improves their quality of life by increasing flexibility and productivity,
and saving time, and 43 percent indicated that this improvement was significant.
Calculating Return on Investment (ROI)
1. Define the term return on investment, and mention that this is a standard method for
measuring the profitability of a project. Discuss the considerations that should be
included when determine the ROI.
2. Explain that there are several models for determining the ROI. Using the list on pages
202 and 203 of the text as a guide, discuss the Intel Corporation’s wireless LAN model
in detail. Mention that this model is generally accepted as the blueprint to follow for
wireless LANs.
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3. Discuss the ROI that Intel’s model yielded for their organization. Mention that they
concluded that the ROI increased as more people were added to the WLAN, because the
average cost per user drops dramatically when adding users, but the benefit stays the
same. Illustrate with Figure 6-2.
Teaching
Tip
Intel recommends that two months be reserved for pilot planning and another
two to three months to actually run the pilot program.
Teaching
Tip
Intel’s approach in determining the time savings from using WLAN was very
conservative. It started by cutting the user-perceived productivity gains by half.
They then cut the time in half again to recognize that not all time savings
necessarily contribute directly to higher productivity and increased ROI.
Teaching
Tip
Intel recommends that once the ROI model is complete, larger organizations
should return to step 1 and reassess the questions and decisions made for the
pilot in light of scaling the WLAN to include more units. When that is
completed, the organization should conduct another larger ROI study by
repeating steps 2 through 4.
4. Using Table 6-2 as a guide, illustrate the costs and benefits of three different sizes of
WLANs over three years based on the Intel model.
Quick Quiz 1
1. True or False: Teamwork has become an essential element in today’s business
economy.
Answer: True
2. Wireless LANs have been shown to add ____________________ hours a day of
productive time per worker.
a. Less than one
b. One to two
c. Two to four
d. Four to five
Answer: b
3. True or False: When reviewing the current network, it is a good idea to create detailed
documentation of the network.
Answer: True
4. ____________________ benefits are benefits that can be easily measured or quantified.
Answer: Hard
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5. True or False: Improved employee satisfaction is an example of a hard benefit.
Answer: False
6. ____________________ is a standard measure of the profitability of a project.
Answer: Return on investment (ROI)
Designing the Wireless LAN
1. Provide a brief overview of the process of designing a wireless LAN.
Determining the Deployment Scenario
1. Explain that the first step in designing a WLAN is to decide upon the correct
deployment scenario. Using the list on pages 204 and 205 of the text as a guide, discuss
the seven deployment scenarios.
2. Mention that the most common type of wireless LAN scenario is an infrastructure
network with the access point(s) connected to the wired infrastructure.
Selecting the IEEE Wireless Network Type
1. Explain that once the deployment scenario has been determined, the next step is
determining which IEEE wireless network type would be best. Mention that the current
choices are IEEE 802.11a, 802.11b, and 802.11g.
Teaching
Tip
Wireless devices labeled “802.11 pre-N” started to appear in 2004 from different
vendors implying that they follow the upcoming IEEE 802.11n standard.
However, the standard has not yet been determined and it could be different from
these “pre-N” devices. Many industry experts recommend avoiding “pre-N”
devices.
2. Discuss the considerations that may affect the type of wireless network selected.
Explain the situations in which it would be appropriate to used each of the three
wireless standards.
Teaching
Tip
The decision does not always have to be between two standards. Access points
and wireless NIC adapters are now available that support two or even three of the
standards. A dual-band 802.11a and 802.11g access point can simultaneously
support both types of wireless networks.
Deciding upon Access Point Management
1. Explain that if an infrastructure wireless network is to be used, a decision must be made
regarding the type of access point management.
2. Describe the concept of a fat access point. Explain that with a fat AP, any configuration
to the wireless LAN must be done through the access point.
CWNA Guide to Wireless LANs, Second Edition
Teaching
Tip
6-7
APs are generally configured through a browser interface.
3. Describe the concept of a thin access point. Explain that the management functions are
moved to an Ethernet network switch. Discuss the advantages and disadvantages of
using thin access points, explaining that they can simplify management and reduce
handoff time. Mention that, currently, all think access points are proprietary.
Teaching
Tip
Some wireless vendors have moved the wireless intelligence to a router instead
of a switch.
4. Explain that several vendors are working on comprehensive network management
solutions that integrate wireless networks into the same deployment, operations, and
management as a wired network.
Determining the Location of the Wireless Devices
1. Discuss the importance of considering the optimal location of the wireless devices in an
ad hoc network or the access point(s) in an infrastructure network. Explain that
interference from other objects and devices is a primary factor to consider. Using Table
6-3 as a guide, discuss some examples of types of object that might be considered, and
the amount of interference that they might cause.
Ad Hoc Mode
2. Explain the three main considerations when designing an ad hoc network. Illustrate with
Figure 6-3.
Infrastructure Mode
1. Discuss the importance of positioning APs correctly for an infrastructure WLAN.
Explain that the interference cause by various objects must be accounted for, and that it
is desirable to not have the signal extend beyond the confines of the building.
Teaching
Tip
Techniques for proper access point location are covered in Chapter 7.
2. Explain the importance of proper channel setting on the APs in an ESS infrastructure
wireless network. Mention that the best option is to make sure that each AP uses a
different channel, when possible. Illustrate with Figure 6-4.
3. Explain that in 802.11b and 802.11g there are 14 staggered and overlapping channels,
and that only channels 1, 6, and 11 do not overlap. Explain the concept of channel
reuse, illustrating with Figure 6-5.
4. Mention that IEEE 802.11a networks have eight nonoverlapping channels, so channel
reuse is not an issue.
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Teaching
Tip
The reasons for the need to have overlapping channels in 802.11b and 802.11g,
while overlapping is not needed in 802.11a, has to do with the use of the ISM
versus U-NII bands. The total bandwidth for the ISM band is much smaller than
for the U-NII band.
Teaching
Tip
Wireless networks that are not properly configured and use overlapping channels
will continue to function, but not as efficiently as they could with channel reuse.
5. Explain that another consideration when positioning access points in an infrastructure
network is to be sure that they properly overlap. Mention that the APs should be
positioned to avoid any gaps in coverage, but that they should not be too close together
either. Using Figure 6-6, illustrate the “flip-flopping” phenomenon.
6. Explain that it is important to consider the number of users that will be associated with
each AP. Mention that it is also important to consider what each of the users will be
doing and the amount of bandwidth that each user will require.
Teaching
Tip
Security for WLANs is a critical element in designing a wireless network and is
covered in depth in Chapters 8 and 9.
Teaching
Tip
When designing a WLAN, it is imperative that you verify that you have coverage
where you want it. Different vendors provide different tools to do this, but one
approach is to use two portable computers with wireless hardware operating on a
point-to-point basis. Using diagnostic software provided by the vendor, you can
determine a coverage area for a potential access point by keeping one portable
computer fixed and moving around with the other.
Deploying a Wireless Network
1. Stress that if planning and designing are done correctly, then deploying can actually be
the easiest of these steps to accomplish.
2. Discuss the factors that must be considered when determining the exact placement of
APs. Stress that they will encounter less interference if places higher. Mention the risks
of placing APs, or any other type of electrical equipment, in a plenum.
3. Explain that if an AP will not be located near a power outlet, PoE can be used. Discuss
the categories of cables that can support PoE.
Teaching
Tip
When possible, access points should also be connected to uninterruptible power
supplies (UPSs).
CWNA Guide to Wireless LANs, Second Edition
Teaching
Tip
6-9
When determining the exact placement of APs, it is important to think in three
dimensions and in terms of the entire organization. For instance, an AP placed on
the ceiling of one floor of a building is still below the next floor up. If such an
AP services more than one floor of a building, there may be differences in the
quality of the signal between the two floors. This issue should be dealt with
during planning, and not during deployment.
4. Explain why, once the physical installation is completed, it is good to configure the
WLAN on its own network segment.
Providing User Support
1. Stress that planning, designing, and deploying a WLAN are all of little value if the users
don’t receive the support that they need to properly and effectively use the new system.
Training
1. Describe the reasons why training is vital to the use of a WLAN. Explain that training
will increase the effectiveness of the WLAN, and consequently limit the drop in
productivity normally associated with the introduction of a new system.
2. Explain that many organization find that a group training session for all WLAN users to
be the most effective setting for training. Mention that the best time for this session is at
the time that users receive their wireless laptops.
3. Mention the importance of setting user expectations for support and specifying how
users should request support.
Support
1. Explain that support involves continuing follow-up in answering questions and assisting
users. Using the first list on page 213 of the text as a guide, discuss some of the ways
that user-support can be organized.
2. Explain that an internal help desk is often one of the best ways to provide support.
Stress that a help desk is a central point of contact for assistance. Using the list on pages
213 and 214 of the text as a guide, discuss some of the suggestions regarding the
creation and operation of a help desk.
3. Stress that gathering user feedback is essential when installing a new wireless LAN.
Quick Quiz 2
1. Most corporate wireless LANs operate in ____________________ mode.
Answer: infrastructure
2. Wireless ____________________ provide a single mechanism for managing and
monitoring the wireless network.
Answer: gateways
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3. In general, if a broader area of coverage is needed, the ____________________
standard should be considered first.
Answer: 802.11g
4. ____________________ access points are access points that lack management
functions.
Answer: Thin
5. True or False: In ad hoc mode, all stations must send and receive signals on the same
frequency.
Answer: True
6. Channel ____________________ calls for adjacent access points to use nonoverlapping
channels so that the access point using one channel will not interfere with its neighbor.
Answer: reuse
7. True or False: The best place to deploy an access point is always in a plenum.
Answer: False
8. A(n) ____________________ is a central point of contact for users who need assistance
using the network.
Answer: help desk
Class Discussion Topics
1. OPNET’s Wireless module is a tool that can be used to simulate a WLAN. The concept
of a simulation is to condense the testing phase of a project while still getting an
accurate idea of the potential for the project to succeed. However, simulation software
is generally expensive and often has a high learning curve to be able to use. Do the
students feel that using simulation software, such as OPNET’s Wireless module, would
be worth the cost and effort to implement the simulation? Why or why not? Can they
think of any other pros or cons of using simulation software?
2. It was cited in this chapter that, on average, the use of WLANs generates one to two
hours of productive work per day per worker. Have the students come up with a number
of examples of how WLANs allow for this extra productivity (For example, workers
can take their laptops with them during lunch and perform research or correspondence).
Additional Projects
1. A number of vendors offer wireless network planning software tools. Have the students
research online to identify two or three wireless network planning tools. They should
record the name of the software (or possibly hardware) and a description of how it can
assist in wireless network planning. Compile the students’ results into a master list that
can be redistributed to the class. Also have the students discuss which tools they think
would be most useful when planning a WLAN, and why.
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2. Have the students imaging that they have been contracted to plan a WLAN
implementation in the building where the class is taught (if there is already a WLAN,
they should pretend that there is not). Have them perform an in-depth analysis of the
benefits of implementing a WLAN in the building, including examining the business
entity and reviewing the current network. The students should generate detailed
documentation regarding the network, such as network diagrams and informational
tables (illustrated in Figure 6-1 and Table 6-1, respectively). This will most likely
require interviewing IT personnel in the department. Finally, they should use the Wi-Fi
Alliance’s WLAN calculator to aid in calculating the benefits (see Project 6-1).
3. As a continuation of the previous project, assume that it was determined that
implementing a WLAN in the building where the class is taught is a good idea. The
next step will be to develop and deploy the WLAN. They should decide on a
deployment scenario (probably infrastructure), and select the appropriate network type.
All decisions must be thoroughly justified. Next, the students should select an
appropriate AP management scheme, and select the hardware and software that will be
used. As part of the hardware/software selection process, they should perform cost
comparisons. Again, all choices must be thoroughly justified in writing. Finally, the
students should create a detailed plan for the exact placement of the APs. In doing this,
they should generate diagrams of the building’s layout and overlay the position of the
access points and detailed descriptions of the coverage provided by each access point
(they should label the channels that each AP will used, and highlight areas where
potential interference or flip-flopping may occur). It should be noted that this activity
could be performed without having performed the previous additional project.
Additional Resources
1. Planning a Wireless Network:
http://www.wi-fi.org/OpenSection/design.asp?TID=2
2. Wireless System Planning Tools:
http://members.shaw.ca/propagation/planning.html
3. Planning and Implementing Wireless LANS:
http://www.networkcomputing.com/netdesign/wlan3.html
4. Planning and Deploying your Wireless Network:
http://www.openxtra.co.uk/articles/wifi-planning-deployment.php
5. Planning WLAN Operational Support:
http://www.wi-fiplanet.com/tutorials/article.php/3078061
6. Designing WLANs with Simulation:
http://www.wi-fiplanet.com/tutorials/article.php/2246571
7. Wireless-LAN simulation tools:
http://www.nwfusion.com/columnists/2004/121304wizards.html
8. Intel SMB Technology ROI Analysis Tool:
http://www.intel.com/business/smallbusiness/roi.htm
9. Wireless LAN ROI:
http://www.intel.com/business/bss/infrastructure/wireless/roi/
10. Wi-Fi Alliances WLAN Benefits Calculator:
http://www.wi-fi.org/OpenSection/WLAN_Calculator.asp
CWNA Guide to Wireless LANs, Second Edition
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11. The "Thin" Access Point Approach:
http://www.wi-fiplanet.com/tutorials/article.php/3318401
12. 802.11 Coverage and Capacity (PDF):
http://www.extricom.com/imgs/Uploads/CoverageCapacityWP.pdf
13. Making the Choice: 802.11a or 802.11g:
http://www.wi-fiplanet.com/tutorials/article.php/1009431
14. Assess Requirements Before Designing WLAN:
http://www.wi-fiplanet.com/tutorials/article.php/1005471
15. Capacity, Coverage, and Deployment Considerations for IEEE 802.11g:
http://www.cisco.com/en/US/products/hw/wireless/ps4570/products_white_paper09186
a00801d61a3.shtml
Key Terms
 Channel reuse: A technique in which adjacent access points use non-overlapping
channels so that the access point using one channel will not interfere with another
access point.
 Fat access point: An access point that includes management functions such as user
authentication, encryption, and access point configuration.
 Hard benefits: Benefits that can be easily measured or quantified.
 Plenum: The space above drop ceilings used to circulate and otherwise handle air in a
building.
 Return on investment (ROI): A standard measure of the profitability of a project.
 Soft benefits: Benefits that are difficult to accurately quantify.
 Thin access point: An access point that lacks processing capabilities and acts only to
link the wireless LAN with the wired network.