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300-425 · Question #204

A customer has two Cisco WLCs configured in a SSO cluster. The wireless network supports a large warehouse. The customer purchases new iPads to replace legacy scanners. Both devices connect to a…

The correct answer is A. Enable FT PSK and set Fast Transition to Adaptive for the Scanning SSID. Since the SSID uses WPA2 Personal (pre-shared key), the correct standards-based fast roaming protocol is 802.11r FT-PSK (Fast Transition with PSK). 802.11r is the IEEE standard for fast BSS transition, which allows clients to pre-authenticate with neighboring APs before…

Mobility

Question

A customer has two Cisco WLCs configured in a SSO cluster. The wireless network supports a large warehouse. The customer purchases new iPads to replace legacy scanners. Both devices connect to a single SSID named Scanning by using WPA2 Personal. The customer wants to use a standards-based method for fast roaming on the new iPads. Which approach meets the scanner requirement and still supports the legacy scanners?

Options

  • AEnable FT PSK and set Fast Transition to Adaptive for the Scanning SSID.
  • BEnable FT 802.1X and set Fast Transition to Adaptive for the Scanning SSID.
  • CEnable optimized roaming globally and enable FT 802.1X on the Scanning SSID.
  • DEnable optimized roaming globally and enable FT PSK on the Scanning SSID.

How the community answered

(23 responses)
  • A
    43% (10)
  • B
    30% (7)
  • C
    17% (4)
  • D
    9% (2)

Explanation

Since the SSID uses WPA2 Personal (pre-shared key), the correct standards-based fast roaming protocol is 802.11r FT-PSK (Fast Transition with PSK). 802.11r is the IEEE standard for fast BSS transition, which allows clients to pre-authenticate with neighboring APs before roaming, reducing roam latency. Setting Fast Transition to 'Adaptive' mode is the key to backward compatibility: in Adaptive mode, the AP advertises 802.11r support, but legacy clients that do not support 802.11r (the old scanners) can still associate using standard authentication. The new iPads, which support 802.11r, will use FT-PSK for fast roaming. This satisfies both requirements on the same SSID.

Topics

#Fast Transition#FT PSK#adaptive fast transition#legacy device compatibility

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