The RabbitMQ Federation plugin has several use-cases; collect messages from multiple clusters to a central cluster, distribute load of one queue to multiple other clusters and when migrating to another cluster without stopping all producers/consumers while doing so.

rabbitmq federation plugin

Information about RabbitMQ Queue federation and information about cluster migration with queue federation can be found here. An article about RabbitMQ Exchange Federation can be found here.

More information about federation is available from RabbitMQ.com.