Data centers present many interesting challenges, such as extreme scalability, location independence of workload, fault-tolerant operation, and server migration. While many data center network architectures have been proposed, there has been no systematic way to compare and evaluate them --- apples-to-apples --- in a meaningful or realistic way. In this paper, we present Ripcord, a platform for rapidly prototyping, testing, and comparing different data center networks. Ripcord provides a common infrastructure, and a set of libraries to allow quick prototyping of new schemes. We built a prototype of Ripcord and evaluated it in software and running on a real network of commodity switches. To evaluate Ripcord, we implemented and deployed several schemes, including VL2 and PortLand. A key feature of Ripcord is its ability to run multiple routing applications, side-by-side on the same physical network. Although our prototype implementation is not production quality, we believe that Ripcord provides a framework for both researchers and data center operators to implement, evaluate, and (eventually) deploy new ideas.