New application architectures and software deployment models are fundamentally transforming the data center. Server virtualization, cloud computing, and everything-as-a-service (XaaS) imperatives are altering data center traffic flows, escalating bandwidth and performance demands, and introducing new security and service orchestration requirements. Legacy data center networks are simply too complex, costly, and rigid to meet the needs of the new on-demand world. Tomorrow's virtualized data center demands more agile, efficient, and scalable networking solutions. This white paper reviews data center trends and describes HP solutions for building cost-effective, advanced data center networks that meet the evolving performance, reliability, and agility demands of the 21st century.