We propose a novel Data Center Network (DCN) architecture, named FCell, which is a tradeoff design in three aspects. First, FCell reflects a tradeoff between DCN power consumption and network performances, which mainly include end-to-end delays and bisection bandwidth. We propose a unified path length definition to characterize end-to-end delays in general DCNs. Comparisons with existing DCN architectures reveal that FCell consumes a moderate amount of power, and achieves generally low end-to-end delays and a satisfiable bisection bandwidth. Second, FCell reflects a tradeoff between switch-centric and server-centric designs. Two basic routing schemes are proposed to show that FCell can place routing intelligence on both servers and switches; thus, FCell can be regarded as a dual-centric architecture, which enjoys both the fast switching capability of switches and the high programmability of servers. Third, FCell reflects a tradeoff between scalability and flexibility. Scalability of FCell comes from its regularity; FCell also supports flexible growth of network size with minimal modifications on its original architecture. Through simulations, we evaluate the performances of the two routing schemes in different traffic conditions in FCell, and verify that our unified path length definition is a useful metric to characterize end-to-end delays in general DCNs.