Specifying the period
Syntax:
aaa port-access web-based <port-list> [logoff-period]<60-9999999>]
Specifies the period, in seconds, that the switch enforces for an implicit logoff. This parameter is equivalent to the MAC age interval in a traditional switch sense. If the switch does not see activity after a logoff-period interval, the client is returned to its pre-authentication state. (Default: 300 seconds)