OpenFlow is a promising candidate for future Internet technology. In the US, OpenFlow-based networks have been installed on several university campuses recently. However, we perceive that there is no structured approach to the operation and management of large-scale OpenFlow-based networks and there are few actual achievements of carrying business traffic on them. The focus of this study is on developing a management scheme of global OpenFlow-based networks integrated into the existing Ethernet-based networks using the tunneling technology. We deployed a nation-wide OpenFlow-based network on the NICT JGN2plus testbed, and demonstrated a high-quality real-time video streaming application to verify the performance and reliability of large-scale OpenFlow-based networks. We also describe the details of technical issues we confronted in the trial operation.