This paper proposes a novel network architecture called cloud control plane (Cloud C-plane) to reduce the power consumption of networks. In Cloud C-plane, the forwarding functions and control functions are decoupled, and the control functions are placed in the cloud. In addition, physical network topology is modified to improve the energy efficiency when the load of traffic changes. The routing engine on a dynamically reconfigurable processor (DRP) is a key component of Cloud C-plane. We implement the prototype of the routing engine on an actual DRP, and the experimental results show the execution time of the prototype is 19 times faster in the shortest path calculation.