Microsoft Windows 8 and Cisco Wireless LAN Controller incompatibility
During the Windows 8 beta and preview program, a colleague and I did some detailed testing of new features in Windows 8 wireless networking particularly around the new EAP-TTLS support. We found some issues which Microsoft fixed, however one problem we found, unrelated to EAP-TTLS, was with certain Broadcom wireless NICs failing to connect to our Cisco wireless network (Lightweight APs with central wireless LAN controllers CUWN). We filed a bug and provided detailed debugging but were disappointed to find the issue still present in Windows 8 RTM. It now seems to be the case that the issue was not with the Broadcom wireless NICs per se, but with the fact that the Broadcom drivers in Windows 8 are Windows 8 logo certified and implement 802.11w (Management Frame Protection) and that it transpires that Cisco wireless LAN controller software has problems in this area, an 802.11w-capable client cannot connect to an SSID on Cisco (controller-based) CUWN using WPA or WPA2 key management with AES encryption, see here for an explanation from Cisco and their official announcement here.
See this //Build conference presentation for Windows 8 wireless networking and particularly the Appendix of the slide deck for more 802.11w in Windows 8 logo certification.
UPDATE: A KB article from Microsoft covering this problem is here.
UPDATE: Having now seen a number of Windows 8 clients connected to Cisco wireless networks running controller software that fixes the 802.11w issue, we have found some clients running Broadcom wireless NICs that have very degraded performance. One such example was a Samsung netbook that had been upgraded to Windows 8 and was using the BCMWL63.SYS driver dated 13/03/2012 version 22.214.171.124; downgrading the driver to the Windows 7 version (BCMWL664.SYS version 126.96.36.199) greatly improved performance. The downlevel driver was obtained from the Samsung support page for the netbook.