Alarm state is maintained by PDSN by comparing usrVHASessionsCurrent with critical, major, and clear alarm thresholds. IF alarm state changes to critical, AND usrVHASessionsTrapsEnabled is true THEN usrVHASessionsCriticalAlarm TRAP will be sent. IF alarm state changes to major, AND usrVHASessionsTrapsEnabled is true THEN usrVHASessionsMajorAlarm TRAP will be sent. IF alarm state changes to clear, AND usrVHASessionsTrapsEnabled is true THEN usrVHASessionsCriticalAlarm TRAP will be sent. IF alarm state changes, THEN usrVHASessionsAlarmTime is updated with the current time regardless of usrVHASessionsTrapsEnabled and usrVHASessionsAlarmChanges is incremented. This allows alarm state and time information to be retrieved by SNMP management stations that don't support SNMP traps or when traps are intentionally disabled to reduce trap processing load on the SNMP management station. Writing a 'clear' value will force the alarm state to go to 'clear'. This will count as a state change and cause a trap if the state was 'major' or 'critical'. This step conceptually occurs before comparing the alarm thresholds. If major or critical thresholds are exceeded, the appropriate state change and trap occur. This means that writing 'clear' may cause 0, 1, or 2 alarm state changes and traps.