You can set the performance threshold to mask the performance events that change within the normal range. In this way, you can focus on the performance events that are severely degraded.
Threshold, also called tolerance, is the extreme value that supports the normal running of the transport network. The performance threshold is used to check whether the equipment is normally running. If a certain performance index exceeds the threshold, you need to notice the performance degrade and handle it.
Normally, you need to leave some margin when setting the performance threshold to ensure that you determine the problem beforehand.