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CWNA Guide to Wireless LANs, Second Edition 1
Planning for a Wireless Network
• “If you fail to plan, then you plan to fail”• Some steps involved in planning wireless
networks similar to planning wired network– Many steps significantly different
• Basic planning steps: – Assessing needs– Weighing benefits– Calculating costs
CWNA Guide to Wireless LANs, Second Edition 2
Assessing Needs: Reviewing the Current Network (continued)
Table 6-1: Current network table
CWNA Guide to Wireless LANs, Second Edition 3
Assessing Needs: Reviewing the Current Network (continued)
Figure 6-1: Network diagram
CWNA Guide to Wireless LANs, Second Edition 4
Determining Benefits
• Hard Benefits• Soft Benefits
CWNA Guide to Wireless LANs, Second Edition 5
Calculating Return on Investment
• Intel Corporation’s wireless LAN model:– Implement a pilot– Develop a report– Assemble data– Calculate ROI
Table 6-2: Three-year WLAN costs and benefits
CWNA Guide to Wireless LANs, Second Edition 6
Designing the Wireless LAN
• Involves determining:– Which deployment scenario is best– Which IEEE wireless network standard should be
used– Type of AP management to implemented– Where wireless devices should be located
CWNA Guide to Wireless LANs, Second Edition 7
Determining the Location of the Wireless Devices
Table 6-3: Interference by objects
CWNA Guide to Wireless LANs, Second Edition 8
Ad Hoc Mode
Figure 6-3: Ad hoc hidden node problem
CWNA Guide to Wireless LANs, Second Edition 9
Infrastructure Mode
Figure 6-4: Interference from using same channel
CWNA Guide to Wireless LANs, Second Edition 10
Infrastructure Mode (continued)
Figure 6-5: Channel reuse
CWNA Guide to Wireless LANs, Second Edition 11
Infrastructure Mode (continued)
Figure 6-6: Flip flop between access points
CWNA Guide to Wireless LANs, Second Edition 12
Deploying a Wireless Network
• If planning/designing done correctly, deploying can be easiest step
• Must consider actual placement of APs– Place APs exactly where they were designed to go– To avoid interference, better to place APs higher
• Be careful if placing APs in plenums• If needed, can use PoE
• Good idea to configure WLAN on own network segment
CWNA Guide to Wireless LANs, Second Edition 13
Providing User Support
• Training• Support
CWNA Guide to Wireless LANs, Second Edition 14
What is a Site Survey?
• Design goals for a site survey:– Achieve best possible performance from WLAN– Certify that installation will operate as promised– Determine best location for APs– Develop networks optimized for variety of
applications– Ensure coverage will fulfill organization’s
requirements– Locate unauthorized APs
CWNA Guide to Wireless LANs, Second Edition 15
What is a Site Survey? (continued)
• When to perform a site survey:– Before installing a new wireless network– Before changing an existing wireless network– When there are significant changes in personnel– When there are changes in network needs– After making physical changes to a building
CWNA Guide to Wireless LANs, Second Edition 16
Site Survey Tools: Wireless Tools
Figure 7-1: Adjusting AP power levels
CWNA Guide to Wireless LANs, Second Edition 17
Site Survey Tools: Wireless Tools (continued)
Figure 7-2: External antenna connectors
CWNA Guide to Wireless LANs, Second Edition 18
Site Survey Tools: Measurement Tools
Figure 7-3: Full-featured site survey analyzer software setup
CWNA Guide to Wireless LANs, Second Edition 19
Site Survey Tools: Measurement Tools (continued)
Figure 7-4: Full-featured site survey analyzer software results
CWNA Guide to Wireless LANs, Second Edition 20
Site Survey Tools: Measurement Tools (continued)
Figure 7-6: Basic site survey analyzer software results
CWNA Guide to Wireless LANs, Second Edition 21
Site Survey Tools: Measurement Tools (continued)
Figure 7-8: Spectrum analyzer
CWNA Guide to Wireless LANs, Second Edition 22
Site Survey Tools: Documentation Tools
Figure 7-9: Sample site survey form
CWNA Guide to Wireless LANs, Second Edition 23
Performing a Site Survey: Gathering Data
• Obtaining Business Requirements• Defining Security Requirements• Gathering Site-Specific Documentation• Documenting Existing Network
Characteristics
CWNA Guide to Wireless LANs, Second Edition 24
Performing a Site Survey: Performing the Survey
Figure 7-10: Position of APs
CWNA Guide to Wireless LANs, Second Edition 25
Performing a Site Survey: Performing the Survey (continued)
Figure 7-11: Coverage pattern
CWNA Guide to Wireless LANs, Second Edition 26
Performing a Site Survey: Performing the Survey (continued)
Figure 7-12: Data rate boundaries
CWNA Guide to Wireless LANs, Second Edition 27
Performing a Site Survey: Creating the Site Survey Report
Figure 7-13: Table of measurements
CWNA Guide to Wireless LANs, Second Edition 28
Performing a Site Survey: Creating the Site Survey Report (continued)
Figure 7-14: Data rate coverage map
CWNA Guide to Wireless LANs, Second Edition 29
Performing a Site Survey: Creating the Site Survey Report (continued)
Figure 7-15: 3-D signal-to-noise ratio plot