Smarts IP: How are ErrorThreshold and MinimumTrafficThreshold related to the Smarts IP HighErrorRate?

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• VMware

Issue/Introduction

Symptoms:
Smarts IP: How are ErrorThreshold and MinimumTrafficThreshold related to the Smarts IP HighErrorRate?

Environment

VMware Smart Assurance - SMARTS

Resolution

How are ErrorThreshold and MinimumTrafficThreshold related to the Smarts IP HighErrorRate event?
Of the Smarts IP ErrorThreshold and MinimumTrafficThreshold, which is used to trigger the HighErrorRate event?

What is the purpose of the MinimumErrorRate threshold used to trigger the HighErrorRate event?

What is the difference between Smarts IP ErrorThreshold and MinimumTrafficThreshold?
 

Both the ErrorThreshold and MinimumTrafficThreshold are used in Smarts IP to control the triggering of a HighErrorRate event.

• ErrorThreshold: This threshold is used as the upper threshold for triggering a HighErrorRate event.
• MinimumTrafficThreshold: This threshold is used to calculate the MinimumErrorRate, which is in turn used as a lower threshold limit for triggering a HighErrorRate event (see following section). 

For Smarts IP to trigger a HighErrorRate event, the error rate received has to be above both the limits of the ErrorThreshold and MinimumErrorRate (calculated using the MinimumTrafficThreshold).  

MinimumErrorRate threshold and the HighErrorRate event
The purpose of the MinimumErrorRate as a minimum threshold limit is to prevent Smarts from generating alarms when the total number of packets is very low, but the percentage is very high. For example, if the system received only 10 packets, but 5 are in error, the error percentage would be 50%. This percentage value would likely exceed the ErrorThreshold used as the upper limit, which is typically nearer to 10%. However, Smarts does not want to generate an alarm when the sampling size is so small. Using the MinimumErrorRate lower limit and ErrorThreshold upper limit, Smarts can require that both of the following conditions are met before it will generate a HighErrorRate event/alarm:

• The required minimum threshold for the number of error packets received (MinimumErrorRate) has been exceeded  
• The upper limit threshold for the percentage of errors (ErrorThreshold) has been exceeded

The High Error Rate event is generated when the condition is met. This condition is computed for every 30 seconds (Correlation interval).

Additional Information

Note: Please be aware that in previous versions of Smarts, MinimumTrafficThreshold was known as ErrorTrafficThreshold.  ErrorTrafficThreshold performed an identical function in the calculation of HighErrorRate, but was not customizable.  It was hard set to a value of 2%.  MinimumTrafficThreshold may be adjusted in Polling and Thresholds under the configuration for Ethernet Interface/Port Performance or Generic Interface/Port Performance.