Wireless Networking

In Windows Server 2003 and Windows XP, the software infrastructure that supports wireless connections was built to emulate an Ethernet connection and can be extended only by supporting additional Extensible Authentication Protocol (EAP) types for 802.1X authentication. In Windows Vista and Windows 7, the software infrastructure for 802.11 wireless connections, called the Native Wi-Fi Architecture (also referred to as Revised Native Wi-Fi MSM, or RMSM), has been redesigned for the following:

• IEEE 802.11 is now represented inside of Windows as a media type separate from IEEE 802.3. This allows hardware vendors more flexibility in supporting advanced features of IEEE 802.11 networks, such as a larger frame size than Ethernet.
• New features in the Native Wi-Fi Architecture perform authentication, authorization, and management of 802.11 connections, reducing the burden on hardware vendors to incorporate these functions into their wireless network adapter drivers. This makes the development of wireless network adapter drivers much easier.
• The Native Wi-Fi Architecture supports APIs to allow hardware vendors the ability to extend the built-in wireless client for additional wireless services and custom capabilities. Extensible components written by hardware vendors can also provide customized configuration dialog boxes and wizards.

In addition, Windows Vista and Windows 7 include several important changes to the behavior of wireless auto configuration. Wireless auto configuration is now implemented in the WLAN AutoConfig service, which dynamically selects the wireless network to which the computer will connect automatically, based either on your preferences or on default settings. This includes automatically selecting and connecting to a more preferred wireless network when it becomes available. The changes include:

• Single sign-on To enable users to connect to protected wireless networks before logon (and thus, allow wireless users to authenticate to a domain), administrators can use Group Policy settings or the new Netsh wireless commands to configure single sign-on profiles on wireless client computers. After a single sign-on profile is configured, 802.1X authentication will precede the computer logon to the domain and users are prompted for credential information only if needed. This feature ensures that the wireless connection is placed prior to the computer domain logon, which enables scenarios that require network connectivity prior to user logon, such as Group Policy updates, execution of login scripts, and wireless client domain joins.
• Behavior when no preferred wireless networks are available In earlier versions of Windows, Windows created a random wireless network name and placed the network adapter in infrastructure mode if no preferred network was available and automatically connecting to nonpreferred networks was disabled. Windows would then scan for preferred wireless networks every 60 seconds. Windows Vista and Windows 7 no longer creates a randomly named network; instead, Windows "parks" the wireless network adapter while periodically scanning for networks, preventing the randomly generated wireless network name from matching an existing network name.
• Support for hidden wireless networks Earlier versions of Windows would always connect to preferred wireless networks that broadcast a Service Set Identifier (SSID) before connecting to preferred wireless networks that did not broadcast that identifier, even if the hidden network had a higher priority. Windows Vista and Windows 7 connect to preferred wireless networks based on their priority, regardless of whether they broadcast an SSID.
• WPA2 support Windows Vista and Windows 7 support Wi-Fi Protected Access 2 (WPA2) authentication options, configurable by either the user (to configure the standard profile) or by AD DS domain administrators using Group Policy settings. Windows Vista and Windows 7 support both Enterprise (IEEE 802.1X authentication) and Personal (preshared key authentication) modes of operation for WPA2 and can connect to ad hoc wireless networks protected by WPA2.
• Integration with NAP WPA2-Enterprise, WPA-Enterprise, and dynamic WEP connections that use 802.1X authentication can use the NAP platform to prevent wireless clients that do not comply with system health requirements from gaining unlimited access to a private network.

In addition, troubleshooting wireless connection problems is now easier because wireless connections do the following:

• Support the Network Diagnostics Framework, which attempts to diagnose and fix common problems
• Record detailed information in the event log if a wireless connection attempt fails
• Prompt the user to send diagnostic information to Microsoft for analysis and improvement