Hello Miguel,
There are currently no options to limit the number of clients on the WLC.
Such a new feature was however addressed through an internally visible enhancement requests:
http://tools.cisco.com/Support/BugToolKit/search/getBugDetails.do?method=fetchBugDetails&bugId=CSCth62315
According to the latest notes, this new feature (limiting the number of clients on a per WLAN basis) should be introduced starting from the next releases of 7.0, the one after the 7.0.98.x train.
Regards,
Fede
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