Because CKAN’s harvesting functionality can be used to pull in metadata from other data portals, CKAN can be used to create a federated network of data portals which share data between each other.
This is useful if, for example, a national portal wanted to aggregate information from local government CKAN instances, or if a topic-specific CKAN instance was created which aggregated a subset of datasets from other CKAN sources.
CKAN supports the DCAT standard for data catalogue metadata, so data can also be federated from other non-CKAN catalogues.