Some alarms are applicable but not counted, because there is limited space on the display. Statistical and hardware alarms. It is important to distinguish between statistical alarms and hardware alarms. These counters are read and reset by software every few seconds. The software then calculates the error rate and generates the appropriate statistical alarm when the threshold is passed.
Alarms are in a hierarchy as shown below.
Hardware alarms are determined by the NTC or CIP firmware. Hardware alarms do cause connection reroutes. The appropriate remote alarm is also sent on the trunk for a hardware alarm. Hardware alarms also have a hierarchy. When a packet line has been broken and restored, the log will show a series of alarms, typically loss of signal, loss of frame, and loss of multiframe as each level of synchronization is recovered.