Certified Wireless Network Administrator (CWNA) PW0-105 Chapter 5 IEEE 802.11 Standards.
Certified Wireless Network Administrator (CWNA) PW0-105 Chapter 12 WLAN Troubleshooting.
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Transcript of Certified Wireless Network Administrator (CWNA) PW0-105 Chapter 12 WLAN Troubleshooting.
Certified Wireless Network Administrator (CWNA)PW0-105
Chapter 12WLAN Troubleshooting
Chapter 12 Overview
• Layer 2 Retransmissions• 802.11 Coverage Considerations• Voice vs. Data• Performance• Weather
2Certified Wireless Network Administrator: CWNA – PW0-105
Layer 2 Retransmissions
• Retransmissions occur when the sending STA does not receive an ACK frame from the target STA
• Layer 2 retransmissions impact performance– Increase overhead– Increase latency and jitter
• Real-time applications are impacted most by retransmissions– All communications are slower
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Layer 2 Retransmissions Causes
• RF Interference• Multipath• Adjacent Channel Interference• Low SNR• Mismatched Power Settings• Near/Far• Hidden Node
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RF Interference
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Multipath
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Adjacent Channel Interference
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Low SNR
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Mismatched Power Settings
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Near/Far
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Hidden Node (Obstruction)
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Hidden Node (Large Coverage Cell)
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Hidden Node (Distributed Antenna System)
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Hidden Node (RTS/CTS)
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802.11 Coverage Considerations
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• Dynamic Rate Switching (DRS)
• Roaming– Layer 3 roaming
• Co-channel interference
• Channel Reuse/Multiple Channel Architecture (MCA)
• Single Channel Architecture (SCA)
• Capacity vs. Coverage
Voice vs. Data
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Performance
• Transmission power rates
• Antenna gain• Antenna type• Wavelength• Free space path loss• Physical environment• CSMA/CA
• Encryption• Application use• Number of clients• Layer 2
retransmissions
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Weather
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• Lightning
• Wind
• Water
• Air stratification
• UV/Sun
Chapter 12 Summary
• Layer 2 Retransmissions• 802.11 Coverage Considerations• Voice vs. Data• Performance• Weather
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