The real-time port state object is a real-time snapshot
metric indicating the threshold level of port license usage.
There are five levels:
'safe' Port usage is within a safe range.
'unknown' Port usage state is currently unknown.
'warning' Port usage is rising, approaching a level
of concern.
'critical' Port usage is precariously close to the limit.
'failure' Port usage has reached or exceeded the maximum
allowable and calls are currently being
rejected.
An administrator may set the required percentage of port
licenses in use needed to reach a given threshold level, with
the exception of the failure level which is reached when the
number of ports checked out is equal to the total number of
licenses ports.