New energy efficient network design algorithm and tool for low power consumption named MIDORI is proposed. Network is used minimum set of nodes and links which can transfer all communication traffic under QoS restriction. QoS restrictions are included hop limit, bandwidth limit reliability and stability. Set-covered problem is applied to this algorithm and all links are modeled as "1" for on and "0" for off. To solve the optimum network configuration, parallel data flow type reconfigurable processer, DAPDNA is applied to solve this problem efficiently. The processor automatically produces the node/link set and confirms traffic QoS requirements. This algorithm can achieve optimum network resources. According to our evaluation results, it can achieve more than 25 % higher efficient than conventional holistic algorithm. And also the evaluation results show the 2 decade faster calculation than conventional sequential method using Pentium II processor. Using the design tool and newly developed remote power controlled L2 switch, experimental network is now under development. Using the proposed algorithm and tool, energy efficient IP/ Ethernet network can be realized. We can estimate that it can reduce about 38K ton CO2 par year.