Chapter 12 WLAN Troubleshooting Certified Wireless Network Administrator (CWNA) PW0-105 Chapter 12 WLAN Troubleshooting

Chapter 12 Overview Layer 2 Retransmissions 802.11 Coverage Considerations Voice vs. Data Performance Weather Certified Wireless Network Administrator: CWNA – PW0-105 2

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 Certified Wireless Network Administrator: CWNA – PW0-105 3

Layer 2 Retransmissions Causes RF Interference Multipath Adjacent Channel Interference Low SNR Mismatched Power Settings Near/Far Hidden Node Certified Wireless Network Administrator: CWNA – PW0-105 4

RF Interference Certified Wireless Network Administrator: CWNA – PW0-105 5

Multipath Certified Wireless Network Administrator: CWNA – PW0-105 6

Adjacent Channel Interference Certified Wireless Network Administrator: CWNA – PW0-105 7

Low SNR Certified Wireless Network Administrator: CWNA – PW0-105 8

Mismatched Power Settings Certified Wireless Network Administrator: CWNA – PW0-105 9

Near/Far Certified Wireless Network Administrator: CWNA – PW0-105 10

Hidden Node (Obstruction) Certified Wireless Network Administrator: CWNA – PW0-105 11

Hidden Node (Large Coverage Cell) Certified Wireless Network Administrator: CWNA – PW0-105 12

Hidden Node (Distributed Antenna System) Certified Wireless Network Administrator: CWNA – PW0-105 13

Hidden Node (RTS/CTS) Certified Wireless Network Administrator: CWNA – PW0-105 14

802.11 Coverage Considerations Dynamic Rate Switching (DRS) Roaming Layer 3 roaming Co-channel interference Channel Reuse/Multiple Channel Architecture (MCA) Single Channel Architecture (SCA) Capacity vs. Coverage Certified Wireless Network Administrator: CWNA – PW0-105 15

Voice vs. Data Certified Wireless Network Administrator: CWNA – PW0-105 16

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 Certified Wireless Network Administrator: CWNA – PW0-105 17

Weather Lightning Wind Water Air stratification UV/Sun 18 Certified Wireless Network Administrator: CWNA – PW0-105 18

Chapter 12 Summary Layer 2 Retransmissions 802.11 Coverage Considerations Voice vs. Data Performance Weather Certified Wireless Network Administrator: CWNA – PW0-105 19