TKIP Michael MIC failures were detected

[Jim Mitts]

I am getting this error on several AP's and then the interface is shutdown for 60 seconds.

How do I determine what is causing these errors?

The errors are generated by many MAC addresses.

[George Stefanick]

I blogged about this on my site ...

So clients can throw bad mics and or packets get mailformed when it hits the radio. You will want to check to see if you have 1 client throwing these or different clients. Check the mac address of the client in the logs. This is also a way to create a DOS attack. There are tools to throw bad mics ...Not saying thats your case.

You can fix this in 2 ways.

1. Move to WPA2/AES

2. turn off counter measure

http://www.my80211.com/voip-labs/2009/12/29/configure-tkip-countermeasure-holdoff-timer-on-wlc.html

http://www.my80211.com/security-labs/2010/5/15/tkip-countermeasure-caught-in-the-wild.html

I hope this helps