Path-based Optimization of NFV-Resource Allocation in SDN Networks

Network Function Virtualization (NFV) and Software-defined Networking (SDN) enable flexible and scalable placement of Virtual Network Functions (VNFs). Existing approaches for optimal VNF selection, placement, and traffic routing use link-based approaches. In this paper, we introduce a path-based mathematical optimization model for the NFV Resource Allocation (NFV-RA-PB) problem. The output is an optimal routing based on paths in conjunction with selection and placement of Virtual Network Functions (VNFs). As the problem is known to be hard and not efficiently to solve, we further introduce a more efficient version of the problem (NFV-RA-KSP) that uses k-shortest paths as input. Our evaluation results indicate that our heuristic is able to reduce the solution space of the optimization problem significantly, and eliminates the exponential complexity of NFV-RA-PB. It allows the computation of near-optimal assignments in reasonable time.