The collection and reporting parameters define the length of the sample-window and aggregate-sample-window and the thresholds that trigger reporting. Two measurement windows are provided to support use cases that require a reporting hierarchy. Both measurement windows include the same configuration options. The threshold values determine when the measurement window is able to update the reported delay value.
The measurement windows use the multiplier command to determine the length of time that the measurement window remains open. The sample window length is multiples of the interval. This window stores the results of individual test probes for a total length of the interval multiplied by the multiplier value. The aggregate sample window multiplier length is the number of sample windows. This window stores the number of results passed from individual sample windows. In the aggregate sample window, the minimum, maximum, and average calculations are based on the results received from the sample window. For example, if the delay metric of interest is the average, the aggregate sample is a collection of averages passed from the sample window. The reporting in the aggregate sample window is as follows.
The minimum is the minimum value for all the averages received.
The maximum is the maximum value from all the averages received.
The average is the average of all the averages received.
The comparison to thresholds and reporting decisions occurs at the end of the measurement window if it completes without termination and is deemed integral based on the window-integrity command configuration. Integrity is a percentage-based calculation that determines the number of samples that must be present in the measurement window for that window to be considered integral. If the number of samples in the window equals or exceeds the number of required samples, the result produced is treated as representative and follows normal post-measurement window processing. However, if the number of samples in the window does not achieve integrity, the result is not considered representative and is only recorded for historical purposes, but is otherwise ignored and not processed. By default, integrity checking is disabled and all results from a measurement window are treated as integral and compared to the configured thresholds.
There are two types of thresholds:
a microsecond increase or decrease, configured using the absolute command
a percentage increase or decrease, configured using the relative command
Thresholding compares the measurement window result to the delay measurement last reported at the end of the successful (completed) measurement window. Reporting is on a per-threshold, per-measurement window basis. If multiple thresholds are reached for a completed measurement window, only one threshold triggers an update to the routing engine. The reporting trigger is recorded with a structure of <Window‟Threshold”threshold>. For example, SampleThrehsoldAbsolute indicates that the absolute threshold in the sample window triggered the report. The report is accompanied by a timestamp and last reported value. When a sample window triggers a new delay measurement, the current aggregate sample window is restarted, preempting any possible reporting from the aggregate sample window. This allows both measurement window types to use the delay measurement last reported as the new benchmark.
Configuration of the measurement windows depends on the specific solution requirements. The two measurement windows collect information regardless of configured thresholds. Both types of measurement windows support their own threshold and integrity configuration. By default, thresholds for both measurement windows are disabled; that is, neither window can report any values to the routing engine.