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Performance Analysis of SDN Northbound Interfaces

One goal of network providers is to allow their customers to establish end-to-end circuits as efficiently as possible. A novel way to tackle this problem is to use network function virtualization (NFV). Indeed, NFV enables network providers to expose their network as a virtual topology so that customers can compute an end-to-end path for their data. With the advent of software-defined networking (SDN), the challenge of updating the network forwarding rules automatically to achieve network virtualization has been largely addressed. However, the design and standardization of the northbound interface between the network provider and the customer are still in their early age. For this reason, in this paper we focus on comparing existing northbound interfaces such as OpenFlow, REST or XMPP. To do so, we first describe the requirements of providing an end-to-end connectivity service, such as quality-of-service, minimum bandwidth or maximum jitter. Next, we analyze which protocols allow to meet the requirements of a customer-to-provider interface for end-to-end connectivity. After that, we implement and compare three customer-to-provider interfaces. The first one uses OpenFlow, the second one XMPP and the third one a REST API. The comparison and results are important to help network providers decide which solution meets their requirements best. Our results show how all interfaces scale well and how the decision of which interface to use depends more on the features offered by each one.