We are at a critical inflection point in the cloud evolution. Enterprise clients are now moving from "sandbox" projects to full-scale production of important IT and business services. The market forecast bears this out: cloud revenue is expected to grow almost 5 times faster than traditional IT. To deliver the cloud's full business value, cloud-enabled data centers require speed, flexibility, cost-effective operation, and scalability. This paper discusses the technical and business requirements of cloud computing, focusing on the networking layer of the cloud.