Question: Why are some MacBook clients sometimes unable to connect to a wireless network?
Product and Software: This article applies to all Aruba controllers and ArubaOS 188.8.131.52 and earlier.
MacBook clients with Atheros NICs have a connectivity problem when band steering is enabled in ArubaOS 3.3.2.
The band steering feature was introduced in ArubaOS 3.3.2. Band steering automatically forces dual-band clients to connect at 5GHz instead of 2.4GHz. The 2.4GHz client status code 17 is sent, which indicates that the AP is too busy to accept any more associations. Band steering greatly improves the total performance of the wireless network.
However, when band steering is enabled, Atheros-based MacBook clients can sometimes lose the wireless connectivity and have trouble recovering it. When this problem happens, an "Access point full" error message is displayed in the system.log of the MacBook airport, as shown here:
more /var/log/system.log | grep airport
Apr 22 09:48:35 test-computer Apple80211Agent: Error:
airportd MIG failed = -14 ((null)) (port = 26127)
Apr 22 09:48:35 test-computer Apple80211Agent: Error joining
TEST-SSID: See administrator (-14 Access point full)
According to the 802.11 specification, status code 17 is sent in 802.11 Auth Response. However MacBooks with Atheros NICs expect the status code 17 in the 802.11 Assoc. Response instead of Auth Response. These MacBooks ignore the response and keep retrying with the same AP, which is a misbehavior that will be fixed in new MacOS.
ArubaOS 184.108.40.206 and later contains an enhancement of band steering that is a workaround for Atheros-based MacBooks. This enhancement provides a 60-second window for persistent clients to connect on 2.4GHz band after the initial 8 management frames in 10 seconds.