Cloud providers still lack simple, efficient and secure ways to provision services across providers, and multi-cloud federation is a promising answer, with blockchain offering a secure platform for negotiating and executing it. The paper evaluates blockchain-based federation over private and public blockchain networks and its integration with a production-ready NFV orchestrator (OSM). It is, to the authors’ knowledge, the first performance comparison of this kind: completing the federation procedure takes about 91 seconds on the public blockchain versus 48 seconds on the private one.