User's Guide

22 Service Level Agreement 74
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values for how many measurement samples may fall outside the defined boundary values
without causing the service level agreement to be considered unfulfilled. The type of the KPI
determines whether measurement samples with values over or under the boundary value are
desired.
Three color coding is used for service levels in the KPIs: green, yellow and red. The percentage
boundaries are defined for green and yellow levels of service.
To attain the green level of service the percentage of measurement samples that fulfill the
boundary value criteria set in the KPI (that is, are over or under the set boundary value,
depending on the type of KPI) must be at least as high as the percentage boundary value set
for the green level in the KPI. If there are too many measurement samples that do not fulfill
the boundary value criteria, the service level falls to yellow. The yellow level functions likewise:
if it is not attained, the service level falls to red.
22.3 Example: Upload throughput KPI
The table below explains how an SLA value is calculated based on target KPI, it’s measurement
and statistical analysis.
Boundary value
above 5,5 Mbit/s
This is a relatively low value. One should bear in
mind that this target is for numerous access
points and the calculation interval might be
rather long.
On the other hand, an alarm might be bound to
this KPI with a higher alarming threshold for
access points with extreme performance
expectations.
Green level
99,0%
At least 99,0% of measured samples must attain
an upload throughput of at least 5,5Mbit/s in
order to attain the green level for the KPI in
question.
Yellow level
95,0%
If the percentage of measured samples that
satisfy the boundary value criteria falls between
95,0% and 98,99% the yellow level is attained.
Red level
below 95,0%
If the percentage falls below 95,0% the service
level can be considered unfulfilled.
22.4 Creating an SLA group
An SLA group can be created in one of two ways:
1. By modifying an SLA template
2. By creating an empty SLA group and adding to it the desired Key Performance
Indicators
When the desired set of KPIs has been added to the SLA group the KPI boundary values can be
set to match the service levels outlined in the actual Service Level Agreement contract.