CWDP CWDP Roaming and Client Mobility 1 — Questions and Answers
Question 1: Which IEEE amendment defines fast BSS transition (FT), reducing roaming latency for real-time applications?
- IEEE 802.11k
- IEEE 802.11r (Correct answer)
- IEEE 802.11v
- IEEE 802.11u
Correct answer: IEEE 802.11r
IEEE 802.11r defines Fast BSS Transition, enabling pre-authentication with target APs to reduce handoff time below 50 ms.
Question 2: What problem does IEEE 802.11k (Radio Resource Management) solve in roaming scenarios?
- Reduces re-authentication time during roaming
- Provides clients with neighbor AP reports to accelerate target AP discovery (Correct answer)
- Enables seamless IP address retention across subnets
- Controls transmit power on the client device
Correct answer: Provides clients with neighbor AP reports to accelerate target AP discovery
802.11k neighbor reports give clients a pre-built list of APs to consider for roaming, eliminating time-consuming full channel scans.
Question 3: What is 'sticky client' behavior and why is it problematic in enterprise WLAN design?
- Clients that support 802.11r and roam too frequently
- Clients that maintain association with a distant AP despite a closer one being available (Correct answer)
- APs that do not release client associations after timeout
- Clients configured to use 2.4 GHz exclusively
Correct answer: Clients that maintain association with a distant AP despite a closer one being available
Sticky clients stay connected to a far AP with weak RSSI rather than roaming to a closer one, degrading throughput and reliability.
Question 4: In the 802.11r fast transition process, what is the role of the 'R0 Key Holder'?
- The RADIUS server that stores EAP credentials
- The first AP in the mobility domain that derives the master session key (Correct answer)
- The client that initiates the roam request
- The controller that manages IP address assignment
Correct answer: The first AP in the mobility domain that derives the master session key
The R0 Key Holder (typically the original authenticating AP or controller) holds the top-level PMK-R0 from which all roaming keys are derived.
Question 5: What IEEE amendment enables BSS Transition Management, allowing APs to suggest better APs to clients?
- 802.11k
- 802.11r
- 802.11v (Correct answer)
- 802.11w
Correct answer: 802.11v
802.11v BSS Transition Management allows APs to send BTM Request frames suggesting clients move to a better AP.
Question 6: What minimum RSSI delta between the current AP and a candidate AP typically triggers a client roam decision?
- 2 dB
- 5 dB (Correct answer)
- 12 dB
- 20 dB
Correct answer: 5 dB
Most clients require at least a 5 dB RSSI improvement at the target AP before initiating a roam to avoid unnecessary thrashing.
CWDP CWDP Roaming and Client Mobility 1
Which IEEE amendment defines fast BSS transition (FT), reducing roaming latency for real-time applications?