Finisar Surveyor manual Thresholds and Alarms

Surveyor

User’s Guide

Thresholds and Alarms

Alarm thresholds are set by specifying the values in the Sample Type, Rising Value, Falling Value, and Interval fields for each alarm row in the alarm table. The numbers or percentages set for rising and falling values are referred to as thresholds. The key to creating a meaningful alarm is to specify these values so you get alerted to the exact network conditions you want to analyze.

The sample type can be set to either Delta or Absolute. The setting for the Sample Type field determines how Surveyor will use the threshold values set in the Rising Value and Falling Value fields.

An absolute sample means that if the occurs. If a value is specified for the value drops below the threshold.

Rising Value is exceeded an alarm event Falling Value, an alarm event occurs when the

A delta sample type means that if a difference between samples increases (rising) or decreases (falling) over time is more than the specified threshold, an alarm event occurs. The Interval field sets the time period between samples. Samples are actually taken at least twice as often as the interval. This allows the detection of threshold crossings that span the sample boundary. For example, if the delta sample is taken twice per interval, the sum of the latest two samples are compared to the threshold.

For most cases, the default Sample Type of delta is more useful. One exception is the MAC Layer Alarm for Utilization. Because utilization is expressed in the Rising Value field as a percentage, the absolute sample type is more useful to catch utilization that exceeds a certain percentage from a baseline of zero network traffic.

Multi-QoS alarms do not use the Sample Type, Rising Value, Falling Value, and Interval fields. A simple threshold value is used to trigger the alarm when the threshold is exceeded.

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