I have XP SP3 installed on a workstation, configured to use 802.1x authentication with a Cisco 3750 switch and a Microsoft NAP server providing RADIUS services.
When I boot up the workstation, 802.1x authentication fails. If I unplug the network cable from the workstation, then plug it back in, the workstation immedately authenticates and grabs and IP address from DHCP.
If I reboot, authentication fails again until I unplug and replug the cable. I can get the same result if I do a "shut/no shut" on the Cisco switch's port.
Obviously, there's nothing actually wrong with 802.1x authentication, or RADIUS or the switch. It's only when the workstation first boots up; I'm guessing that while it's booting up, some service(s) are still coming up and preventing authentication from working, but once the workstation has finished booting, it is stuck in the switch's "failed authentication" vlan, and the only way to restart the authentication process is to break the network connection.
Since I'm going to deploy 802.1x to a couple of thousand workstations, unplugging cables or reseting switch ports isn't a practical solution.
Does anyone know how to resolve this problem? Thanks.