Proposal of GRPC As a New Northbound API for Application Layer Communication Efficiency in SDN

Software Defined Networking (SDN) is a programmable network technology which aims to move an existing controller role in hardware equipment into an area of software. The control layer employs an application programming interface (API) to communicate with the application and infrastructure layers as it is centered between two layers. As the Southbound API used in communication with the infrastructure layer, the OpenFlow is defined as the current de factor standard in most SDN controllers. In contrast, the Northbound API used in communication with the application layer had no standard. Only REST API is used in Floodlight or OpenDaylight. Thus, the development in application area where SDN's true value lies to achieve network intelligence is not promoted well enough. In this paper, a gRPC protocol is proposed as useable Northbound API rather than REST API used in some controllers, and applicability of new standard as Northbound API is investigated.