CWS WLAN Roaming and QoS Questions and Answers Flashcards

Which QoS mechanism in 802.11 replaces the legacy DCF for differentiated traffic handling?

Answer: EDCA (Enhanced Distributed Channel Access)

EDCA is the contention-based QoS mechanism introduced with 802.11e that provides differentiated channel access for four traffic categories.

What roaming threshold metric do most enterprise WLAN controllers use to trigger a client roam?

Answer: RSSI below a configured dBm threshold

Enterprise controllers monitor client RSSI and trigger load-balancing or roam suggestions when signal drops below a configured threshold.

In 802.11r, what is stored in the PMK-R0 key holder?

Answer: The top-level fast transition key derived from the master session key

PMK-R0 is the top-level key in the 802.11r key hierarchy, stored at the R0 Key Holder (typically the WLAN controller).

Which TXOP parameter in WMM defines the maximum time a station may transmit after winning channel access?

Answer: TXOP Limit

The TXOP Limit sets the maximum duration a station can hold the channel and transmit a burst of frames after winning the contention.

What is the primary benefit of deploying both 802.11k and 802.11v together in an enterprise WLAN?

Answer: Clients receive neighbor reports AND network-assisted roaming suggestions for seamless handoffs

802.11k provides neighbor lists and 802.11v enables the network to direct clients to better APs, together enabling intelligent, low-latency roaming.

What does DSCP marking accomplish for wireless QoS in a unified wired/wireless network?

Answer: Maps IP-layer traffic priority to WMM Access Categories across the wired-wireless boundary

DSCP values in IP headers can be mapped to WMM ACs at the AP, allowing end-to-end QoS across wired and wireless segments.