Why do I receive alarm messages?

If the the delay between two Test Boxes changes significantly, then an email will be sent to the operators of those boxes.

The alarm uses a "long-term average, short-term average" (LTA-STA) algorithm, which compares certain percentiles and medians for a 30-day interval with dito for a 30-minute interval. More specifically, if the 5th percentile for the shorter interval exceeds the 95th percentile for the longer one, i.e. 95% of recent observations are higher (or worse) than 95% of values registered over the past 30 days, then an alarm will be sent to the specified operators every 30 minutes until the condition disappears. The LTA-STA algorithm will adjust to daily descepancies in traffic patterns by deviding the day into four 6-hour-intervals (0.00-6.00, 6.00-12.00 etc) and then comparing them separately to avoid false alarms.

Click here for more information about Test Box alarms.