Data centers power the most demanding interactive, storage, and cloud services in the Internet, all requiring the highest levels of availability. Bandwidth and scale demands are growing exponentially, doubling approximately every year. This makes data center network architecture is a critical and rapidly evolving enabler to new services and programming models in the data center. This talk starts with some background and motivation for some of the problems in data center networking. We conclude by looking at Google's Data Center network software and hardware architecture, which must deliver cost-effective networking to tens of thousands of servers, all while maintaining operational simplicity.