CWNA Guide to Wireless LANs, Second Edition 1 Planning for a Wireless Network “If you fail to...

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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

Assessing Needs: Reviewing the Current Network (continued)

Table 6-1: Current network table

Assessing Needs: Reviewing the Current Network (continued)

Figure 6-1: Network diagram

Determining Benefits

• Hard Benefits• Soft Benefits

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

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

Determining the Location of the Wireless Devices

Table 6-3: Interference by objects

Ad Hoc Mode

Figure 6-3: Ad hoc hidden node problem

Infrastructure Mode

Figure 6-4: Interference from using same channel

Infrastructure Mode (continued)

Figure 6-5: Channel reuse

Infrastructure Mode (continued)

Figure 6-6: Flip flop between access points

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

Providing User Support

• Training• Support

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

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

Site Survey Tools: Wireless Tools

Figure 7-1: Adjusting AP power levels

Site Survey Tools: Wireless Tools (continued)

Figure 7-2: External antenna connectors

Site Survey Tools: Measurement Tools

Figure 7-3: Full-featured site survey analyzer software setup

Site Survey Tools: Measurement Tools (continued)

Figure 7-4: Full-featured site survey analyzer software results

Figure 7-6: Basic site survey analyzer software results

Figure 7-8: Spectrum analyzer

Site Survey Tools: Documentation Tools

Figure 7-9: Sample site survey form

Performing a Site Survey: Gathering Data

• Obtaining Business Requirements• Defining Security Requirements• Gathering Site-Specific Documentation• Documenting Existing Network

Characteristics

Performing a Site Survey: Performing the Survey

Figure 7-10: Position of APs

Performing a Site Survey: Performing the Survey (continued)

Figure 7-11: Coverage pattern

Performing a Site Survey: Performing the Survey (continued)

Figure 7-12: Data rate boundaries

Performing a Site Survey: Creating the Site Survey Report

Figure 7-13: Table of measurements

Performing a Site Survey: Creating the Site Survey Report (continued)

Figure 7-14: Data rate coverage map

Performing a Site Survey: Creating the Site Survey Report (continued)

Figure 7-15: 3-D signal-to-noise ratio plot

CWNA Guide to Wireless LANs, Second Edition 1 Planning for a Wireless Network “If you fail to...

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