WLC 7.3 and HA

Question

case :
1x 5508 112 ap license
1x 5508 HA sku
http://www.cisco.com/en/US/products/ps10315/products_tech_note09186a0080bd3504.shtml#combo1
what does mean:
With the new WLC coming up, HA SKU at the time of paring will get the AP Count:
If the new WLC has a higher AP count than the previous, the 90-day counter is reset.
If the new WLC has a lower AP count than the previous, the 90-day counter is not reset.
After switchover to a lower AP count, the WLC offset timer will continue and nagging messages will be displayed after time expiry.
in particular what "an higher AP count than the previous" means?
after switchover to primary restored wlc (112 licence) the counter is not reset and buying new licences for primary is needed?
and the difference between HA sku and 50 ap licence for the standby?
thank you

Answer 1

N+1 High Availability Overview
http://www.cisco.com/en/US/docs/wireless/technology/hi_avail/N1_HA_Overview.html
With Release 7.4, an  HA-SKU secondary controller can be configured as a backup controller for  N+1 HA. For example, the following can be used as an HA-SKU controller:
–5508 Series Standalone controller with 50 AP license
but once primary controller fails and all the AP on primary controller gets register on to the HA-SKU secndary WLC till 90 days it works okay but after 90 days you get the warning message that license are not sufficient to serve AP's
http://www.cisco.com/en/US/docs/wireless/technology/hi_avail/Licensing.html#wp1054850 - license error