# Set Up Vertex Entropy

Vertex Entropy is a Moogsoft AIOps algorithm that indicates the critical nodes within your network and their tendency to produce important events. See Vertex Entropy for more information.

## Before you begin

Before you perform the Vertex Entropy calculation and enable its associated features, ensure you have met the following requirements:

• You have a map of the connected nodes in your network in a comma-separated value (.csv) file.

• Your .csv topology file contains all of the nodes that you expect to send events.

• You have run the topology builder utility to import your network topology. See Import a Topology.

## Calculate the Vertex Entropy

To enable the features associated with Vertex Entropy, follow these steps:

1. Import your network topology .csv file into the database using the topology builder. See Import a Topology for more information.

2. Run the Graph Analyser from \$MOOGSOFT_HOME/bin to calculate the Vertex Entropy for the nodes or "vertices" in your network. This is a one-off calculation:

./graph_analyser

Graph Analyser disregards any weight values included in your imported network topology. See Graph Analyser Command Reference.

Once the Graph Analyser has run and each node has a Vertex Entropy value, you can start using these values in other areas of Moogsoft AIOps.

## Add a Vertex Entropy filter

You can use Vertex Entropy as either a trigger or an exclusion filter in a Cookbook Recipe. These filters include or exclude alerts with similar importance in terms of network connectivity. For example, you can set a trigger so Cookbook considers alerts with a Vertex Entropy value of over 0.5 for Situation creation.

To add a trigger filter:

• In your Cookbook Recipe, enter the following in the Trigger Filter:

'vertex_entropy' > 0.5

Alternatively, you can create an exclusion filter to prevent alerts with a Vertex Entropy value of less than 0.3 from creating a Situation:

• In your Cookbook Recipe, enter the following in the Exclusion Filter:

'vertex_entropy' < 0.3

You can add a seed alert filter to a Recipe to ensure Cookbook only creates a new Situation if an alert matches the provided filter value.

For example, if you only want to create Situations when there is an issue with the most critical nodes in your network, you can set the seed alert filter to only create Situations from alerts with a Vertex Entropy value of 1.0:

• In your Cookbook Recipe, enter the following in the Seed Alert Filter:

'vertex_entropy' = 1

If enabled, the initial seed alert must meet both the trigger and seed alert conditions. For more information, see Configure a Cookbook Recipe.

The seed alert filter is not specific to Vertex Entropy and can be used for other conditions such as severity.

## Add a hop limit

You can add a hop limit so that Cookbook clusters alerts from nodes within a certain number of hops from each other. You can use this alongside Vertex Entropy trigger or exclusion filters.

In this diagram, a hop limit of '3' means Cookbook includes alerts from all nodes between node A and node D.

To add a hop limit:

1. In your Cookbook Recipe, check the Hop Limit checkbox.

2. Enter '3' in the Hop Limit field.

The hop limit ensures that Cookbook only clusters alerts that originated from nodes that are close together. For more information, see Configure a Cookbook Recipe.