Cloud Computing has seen phenomenal growth in the last few years. Although large enterprises see a lot of gaps like vendor lock-in with both Public Cloud offerings as well as Private Clouds leading to slower adoption than expected. Federated Clouds may be able to solve the problem. Cloud Federation brings together cloud resources from public as well as private environments so that enterprises can choose an environment on-demand that makes sense for their particular workloads across vendors. While doing so, it also provide a unified access and view of these resources allowing enterprises to easily manage, monitor and meter them. The aim of the presentation is to understand the need of a federated cloud and a reference architecture to go about building one.