Aironet 1100 WPA MIC failure EAPOL

agebrahimi · ‎08-18-2005

Hi All,

The wlan client is connected properly to the AP.

The ping from AP to client or vice versa does not work.

1)If I do ping from AP to client:

I observe that the ARP request from AP to client gets ARP response back successfully.

However the ping request packet (received at client from the AP) gets a MIC error at wlan client.

If another ping request is sent to client then the client sends EAPOL-Key message with the MIC

failure indication to AP(two MIC failures within 60 seconds). This results in disconnection of the client from AP.

2)If I do ping from client to AP:

I observe that the ARP request from client gets ARP response back successfully.

However the ping reply packet (received at client from the AP) gets a MIC error at wlan client.

If another ping reply is received at client then the client sends EAPOL-Key message with the MIC

failure indication to AP (two MIC failures within 60 seconds). This results in disconnection of the client from AP.

In summary the very first packet received at the client from AP is ok but the second and the subsequent packets

gets MIC error at the client.

What could be wrong with the AP that's resulting in MIC errors at the client?

Could it be because of the Sequence counters not being set properly? If so then how can I verify and correct it?

What are the possible reasons for getting the MIC failure at the client side?

Any help is appreciated.

smahbub · ‎08-23-2005

When we get MIC errors it means that there is attempt to heck the network by an unauthorised user. When this happens the associations to the AP are dropped and you get MIC errors on the client. Check for rogue access points which may be trying to attack or interfere with the wireless network. This is the workaround for this.

scottmac · ‎08-23-2005

If you are using an Intel client NIC/PCcard/Centrino chipset, make sure you have the latest drivers (from Intel or your client).

We had this error from several of our laptops, all runing Centrino. Once the drivers were updated, the errors went away.

FWIW

Scott

agebrahimi · ‎08-23-2005

Thanks smahbub and Scott for your replies.

I have just checked and we are all running the latest drivers.

The problem is peculiar because the Aironet 1100 is configured as a repeater and the host is a Cisco 871W router. Only when the clients associate to the Aironet 1100 does the AP crash. And when the 1100 crashes, the 871W maintains wireless operability!