HI,
Please check these links:
http://networkguy.de/?p=558
http://www.cisco.com/c/en/us/td/docs/wireless/technology/hi_avail/N1_High_Availability_Deployment_Guide/Licensing.html
http://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/7-5/High_Availability_DG.pdf
Hope this helps.
Regards
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