Software-as-a-service (SaaS) is shifting the need for computing resources from an infrastructure, hardware and software ownership model toward a subscription and capacity on demand model. This model favors cooperation between network infrastructure and data center operators to deliver a huge increase in required data bandwidth. Despite unexpected and early entries from companies such as Amazon in the cloud provider business, as well as several infrastructure companies with a substantial size, large Internet companies with huge subscriber bases lead in the design of distributed cloud data centers. For example, Google is currently believed to operate 17 data centers in the U.S. and 16 more across the globe. The company is estimated to run close to 2 million servers in those data centers at this time.