OpenFlow and Multi-layer Extensions: Overview and Next Steps

Even though software-defined networking (SDN) and the OpenFlow protocol have demonstrated great practicality in the packet domain, there has been some hesitance in extending the OpenFlow specification to circuit and optical switched domains that constitute wide area multi-layer transport networks. This paper presents an overview of various proposals with regards to extending OpenFlow to support circuit switched multi-layer networks. The goal is to shed light on these ideas and propose a way forward. This paper favors a top-down approach, which relies on transport network's main SDN use case: packet-optical integration, to help identify the sufficient extensions for OpenFlow to support circuit/optical switching.