The size of medical information such as CT and MRI images is very large and becomes typical big data. In the near future, more efficient and sophisticated medical treatment based on big data will be required. For example, medical doctors will determine the name of a disease with the assistance of a combined system of big data and AI. In our laboratory, we research and educate on network technologies to transmit and process big data efficiently. The research themes are highly distributed cloud computing environment, design of virtual networks, technologies to upgrade the speed of the Internet, technologies to increase the fault tolerance of the Internet, smart networks based on IoT (Internet of Things), optical networks.