The distribution model describes the ALE message flows between logical systems.
You can specify the relationships between logical systems, message types, BAPIs and filters in the distribution model. Applications and the ALE layer use the model to determine receivers and to control the data distribution.
For more information about maintaining the distribution model see the Customizing Implementation Guide (IMG):
In the distribution model you can specify the messages to be sent to a given logical system. You can also define the conditions for the content and dispatch of messages in the filters.
The distribution model consists of one or more views that you can define. With more complex distribution tasks you can assign business sub-areas or groups of logical systems to separate views.
The relevant views of the distribution model must be available in all the logical systems involved in ALE. You can find the functions for distributing views in Customizing for ALE.