I have network configured to use 802.1x authentication with a Cisco 3750 switch and a Microsoft IAS server providing RADIUS services. And customers use windows xp and windows 7 installed on a workstation. When they boot up the workstation, 802.1x authentication work, vlan is change. But client dont grab ip adress from DHCP If they unplug the network cable from the workstation, then plug it back in, the workstation immedately authenticates and grabs and IP address from DHCP. If they reboot the problem appear again, until they 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 search in google and find that this issue may occur if NAP agent has not yet started when the client first requests a DHCP address. I try sc config dot3svc depend= napagent on the problemaitc client. It is help with windows xp, but it do not help with windows 7. Does anyone know how to resolve this problem in windows 7? Thanks.

Hi, This issue may be caused by the NAP service started after the DHCP service so that this issue occurs. You may try to establish dependence between NAP and DHCP to resolve this, but I have never tried this so I can’t recommend it. As you say, you already tried the 802.1X enforcement method. So as I mentioned, I do not recommend this but you could try sc config dhcp depend= napagent. Hope this helps.Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

You can try Enforcement Reporting Mode: http://technet.microsoft.com/en-us/library/dd314198(WS.10).aspx

dont help Thank you for answer!!!