Research On Northbound Interface Of SDN And Its Testing

Software Define Network (SDN) is a new pattern of network architecture. It's main feature is decoupling the data plane and control plane of the traditional network and providing an open and programmable northbound interface to the upper application to achieve the purposes that are flexible orchestration of network resources and rapid deployment of new protocols, maximumly open network resources.In this network architecture, SDN northbound interface as the key technology to promote innovation in network services, is getting more and more attention by the standardization organizations and controller manufacturers. Because of different controller developers face different SDN application scenarios with different understanding, the controller did not form a unified standard in the industry, which gives the upper application developers in the selection of the controller a very Big challenge which is high cost of learning, so the standardization of the northbound interface is the focus of competition in SDN fields now. How to design a reasonable, good scalability northbound interface of SDN controller is one of the main direction of industry to continuously to explore and research.SDN International Standard Organization ONF (Open Network Foundation) with its famous SDN South interface standard protocol OpenFlow occupies the main position of SDN standardization field. The ONF working group related the northbound interface are: Northbound Interface Working Group (NBI-WG) , which divides SDN northbound interfaces with different degrees of abstraction, to accelerate the wide commercial deploy of SDN by standard interface and functional identification. The ONF Information Model Working Group (IMP),which develops the NBI information model, defines a core / base NBI(northbound interface ) to cover the common SDN controller capabilities and functions, providing the controller a neutral data model in a programming language, and it can be formed with the protocol-related interface by mapping to data schema.With the good prospect of SDN, more and more companies are willing to participate in SDN research and development. At present,REST API become the main way of SDN northbound interface with the advantages of its natural resources abstraction and the simple,programmable features , but REST is an architectural style, different developers according to their understanding to define their own interface which bring difficulties to SDN northbound interface standardization and multi-domain controller co-deployment. In order to ensure the understanding of the SDN protocol with consistency and correctness between different vendors, we need to test the controller conformance before the controller deployed in the production environment. At present,there are few researches on the SDN Northbound interface test, and different interface specifications needs different test platform, which increases the cost of SDN northward interface test.Based on the above background, the main contents of this paper include the following three aspects:First of all, researching deeply in SDN northbound interface and testing areas. Participating in the related project of Northward Interface Standardization of Telecommunication Research Institute of Ministry of Industry and Information Technology and based on the general information model proposed by ONF, we pruned and refactored the northbound interface information model to information model based on transport network.Secondly, we study how to build the north interface of the SDN with good scalability, that is, how to model the north interface of the controller,and generate flexible and extensible north interface to the controller, then we develop a conversion tool to generate a code frame.Thirdly, study the common SDN northbound interface test method,and propose modeling controller interface by using YANG model and develope a platform to test different SDN Northbound interface conformance specification by using different YANG model.