How does baseline calculation work?

Baselines are multiweek rolling averages of monitored data.

Cisco Provider Connectivity Assurance (formerly Skylight performance analytics) maintains a baseline for every metric of each monitored object. The baseline is a running average of what a metric looks like for a particular hour of the week (for example, 8 PM on Wednesdays). You can visualize this baseline in the object details view.

Baselines appear as a dotted line in line on a per session basis in Inventory.

Tip: You can use baselines to generate Dynamic Thresholds, providing more realistic thresholds that correspond to per-object behavior.

Understanding Baselines

Baselines are based on the following attributes:

• Default Granularity = 3600 seconds / 1 hour
  • All data points within the Granularity window are averaged and stored for each indicator
• Default Number of Weeks that they are kept = 4
  • Baselines are considered reliable once this number of weeks has passed
• One week (seven days) of baseline data must be accumulated before baseline data can be used in graphs

Notes:

We do not recommend you set baselines to work at 15m granularity (instead of 1h) as this will impact performance and require substantial reworking of infrastructure on how baseline data is generated/stored.

The default cleaning threshold is set so that 1/60 (1.667%) of dirty data is discarded. Error states automatically trigger data cleaning and cannot be disabled. Setting the threshold too low reduces the value of your baselines, so data cleaning is not recommended in this case.

Baseline Calculation Example

The following is an example of calculating Baseline (BL) datapoint for Monday 10 AM for a Metric(M) SMA (Simple Moving Average) over a six-week period:

Mavg is the Metric average.
Mavg_Mon_10_w1 is the Metric Average value for Monday 10 am on week 1.

Caution: Changing the Granularity setting deletes all previous baseline data.

By default, baselines are calculated and stored for all indicators that are collected, but there may be situations in which baselines are not needed, such as:

• Non-critical Device Groups
• Unimportant Object Groups
• Static Indicators (for example, amount of RAM installed in a server)

Show or Hide Baselines

To show or hide baselines

1. Click the Inventory icon in the left sidebar.

2. Select a session.

3. Navigate to the Performance tab.

4. Click the Baseline checkbox in the upper-right corner.