Smarts | Unsure if HighCollisionRate Calculation is correct / How is HighCollisionRate calculated

Products

• VMware Smart Assurance

Issue/Introduction

Symptoms:


There may be an instance in which you want to manually check the calculation for HighCollisionRate. 

IP Performance Manager detects a HighCollisionRate fault when the rate of collisions exceeds the CollisionThreshold. This threshold is contained in the Ethernet Interface/Port Performance setting.

Environment

VMware Smart Assurance - SMARTS

Resolution

These are the calculations associated with HighCollisionRate

HighCollisionRate calculation :
event HighCollisionRate
"Indicates that the rate of collision exceeds CollisionThreshold."
= if NetworkAdapterOperational && CollisionThreshold < 100
check (OutputPacketRate > 0) &&
(CollisionRate > MinimumCollisionRate) &&
(CollisionPct > CollisionThreshold);
 
attribute float CollisionRate
"The rate of collisions expressed in packets per second as detected "
"by this interface."
= 0.0;
 
readonly computed attribute float MinimumCollisionRate
"The minimum collision rate needed to trigger the "
"HighCollisionRate event."
= (((MaxSpeed > 0 && MaxTransferUnit > 0) *
(my_MaxSpeed / MaxTransferUnit / 8) * 0.1) +
((MaxSpeed == 0 || MaxTransferUnit == 0) * 50)) else 0.0;
 
attribute unsigned CollisionThreshold
"The upper threshold for collisions expressed as a percentage "
"of the total number of output packets."
= 10;