SDH allows the sky to achieve the Alarm on the various equipment. These alarms correspond to different problems could exist on the equipment or connections. Major alarms are: • AU-AIS (Administrative Unit Alarm Indication Signal) • AU-LOP (Administrative Unit Loss of Pointer) • HP-UNEQ (HO Path Unequipped) • HP-RDI (HO Path Remote Defect Indication) • LOF (Loss of Frame) Frame Loss • LOS (Loss of