OS X Stops Communicating if MCS Rates are Disabled:
CSCub82468 WLC should not allow disable of MCS rates on 800ns guard interval
+Resolved in 22.214.171.124
CSCug65693 Macbook client bug causing connectivity problem w/ recent OS X update
+Resolved in 7.4.110, 7.5.102, 7.6.100
CSCuh64372 OS X supplicant pauses 10 seconds during PEAP authentication after roam
This is an issue in OSX, not a bug on the infrastructure side. The supplicant tries to perform a certificate revocation check while in the middle of EAP authentication, but this will always fail, because the client does not have network connectivity utill EAP is complete.
CSCug27515 Incorrect 802.11 Block ACK segment calculation for winstart/winend
Broadcom MacBooks running 10.7/10.8 can experience stalled transmissions, when they get into a state where they are trying to transmit two frames of which one is past the A-MPDU window.
OS X 10.7 (Lion) Clients Dropping from WLAN Following Upgrade
MacBook Pro continuous Association to the WLAN with system mode network configuration
If a system mode network is configured with any EAP type, on occasion with OS X 10.8.4 (possibly other builds also) the client MacBook will attempt to reconnect to the WLAN every 60 seconds for a period of up to several minutes. The issue lies with a process on the Apple client not launching properly. When this process fails to launch, the 'airportd' daemon process forces a reconnection to the network. Each time the aforementioned process fails to load, airportd will again force the reconnection after 60 seconds, causing the client's wireless connection to be dropped during these events until it connects again. The Apple client conducts a full association and authentication process during each instance.
Workaround: Avoid all 802.1X/EAP types and configure the WLAN and client supplicant for PSK instead.