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802.1x DHCP issues with XP

DMcCoy_1
Occasional Advisor

802.1x DHCP issues with XP

I've just implemented 802.1x on my network and I'm having big problems with DHCP. My clients are picking up a dhcp address from the guest vlan during boot and then requesting it again after authenticating. This fails and an ip from the correct range is obtained.

However, during this delay the XP clients either miss part of the group policy, all of it or have a netlogon error.

I believe I could fix it with the unauth-period by stopping guest vlan access for enough time for windows to request an address after initiating authentication.

I have a problem though, all my edge switches are 2800, 2600 and 2500. Does anyone know if this feature is likely to make it to the lower series switches? or a way to use the other auth timing features to achieve the same effect.

As it is, my 802.1x implementation is going to be a disaster as I miss things like startup scripts on nearly all my windows clients. I really don't want to use static addresses.

Any other suggestions are welcome!
1 REPLY
DMcCoy_1
Occasional Advisor

Re: 802.1x DHCP issues with XP

I think I have it working! I've added the SupplicantMode = 3 to the EAPOL config on the xp machines. I'm still getting a dhcpnack from the dhcp server, but it seems to resolve it within a second or so, which I assume is the authentication. It no longer gets a dhcp address from the guest vlan between boot and auth. I've got more testing to do, but 3 machines I've tested now get the policy on boot.