SCOR: constraint programming based northbound interface for SDN

In this paper, we introduce SCOR (Software-defined Constrained Optimal Routing), a new SDN Northbound Interface for QoS routing and traffic engineering. SCOR is based on constraint programming techniques and is implemented in the MiniZinc modelling language. It provides a powerful, high level abstraction, consisting of 9 basic constraint programming predicates. A key feature of SCOR is that it is declarative, where only the constraints and utility function of the routing problem need to be expressed, and the complexity of solving the problem is hidden from the user, and handled by a powerful generic solver. We show that the interface (set of predicates) of SCOR is sufficiently expressive to handle all the known and relevant QoS routing problems. We further demonstrate the practicality and scalability of the approach via a number of example scenarios, with varying network topologies, network sizes and number of flows