A rttMonThresholdNotification indicates the occurrence of a threshold violation for a RTT operation, and it indicates the previous violation has subsided for a subsequent RTT operation. Precisely, this has resulted in rttMonCtrlOperOverThresholdOccurred changing value. When the RttMonRttType is 'pathEcho', this notification will only be sent when the threshold violation occurs during an operation to the target and not to a hop along the path to the target. This also applies to the subsiding of a threshold condition. If History is not being collected, the instance values for the rttMonHistoryCollectionAddress object will not be valid. When RttMonRttType is not 'echo' or 'pathEcho' the rttMonHistoryCollectionAddress object will be null. rttMonThresholdNotification object is superseded by rttMonNotification.