CSCwm49467 - Flex APs disable u-APSD in the assoc resp if clients dont

[andre-dujeu]

Hello, can this bug explain the following behaviour: several users in a meeting room roaming at the same time from the closest to another AP (with lower RSSI and SNR). ISE login message indicates "NOTICE RADIUS: Endpoint abandoned EAP session and started new" and "FailureReason=5440"

[ammahend]

doubt that, based on your ISE log it indicates that ISE is sending an Access-Challenge but, ISE receives Access-Request instead of receiving a response to the challenge.

the Bug has to do with client sleep mode and wake up control for better battery life and optimum response, U-APSD is particularly beneficial for applications sensitive to latency and jitter, such as voice and video over Wi-Fi

Moreover you are failing at advanced authentication, you are already passed association state, May be a good idea to open a TAC case.

[Flavio Miranda]

@andre-dujeu 

" (with lower RSSI and SNR)" this is something no one will never know. RSSI and, therefore, SNR will vary all the time and makes it impossible to measure exactly. We are talking about a wave (magnetic field) facing interference thus variation all the time.

The problem rely on the fact that, wireless client will look only at the RSSI value at speficic moments and will ignore all the rest. If the signal vary, and it will, clients move to another AP just because the RSSI they see now is higher then the previous one. This is hard coded in any wireless client firmware. Wireless client vendor could do better and make the algorithm smarter but it would required collect information by sniffing all the channels to gether information  and it would cost a lot of battery and they prefer to offer poor wireless experience then lower down battery charge pretty fast.

 The alternatives wireless admin have is:

 - work with better wireless clients in the market, usually Intel when it comes to Cisco.

- Keep the most up to date driver on the wireless client.

-Make sure the coverage is perfect by running site survey and positioning the access point properly.

-Deal with wireless client inefficiency all the time

Now, ""NOTICE RADIUS: Endpoint abandoned EAP session and started new" and "FailureReason=5440" this should not be related to roaming. Roaming does not trigger new authentication. This logs would be consequence of client disconnection and not roaming. Make sure the AP on the conference room is not crashing.