Balanced resource allocation for VNF service chain provisioning in inter-datacenter elastic optical networks

Network Function Virtualization (NFV) is a novel technology that enables flexible and cost-effective network services by replacing the hardware-based middleboxes with software instances named virtual network functions (VNFs). In NFV, each requested Service Function Chain (SFC) is an ordered sequence of VNFs that must be placed optimally on the geographically distributed data centers (DCs). For the popular Elastic Optical Networks (EONs) with flexible bandwidth management, a major challenge is optimal placement of the VNF-based Service Chain (VNF-SC) on data centers and steering traffic through deployed VNFs in the substrate network. In this paper, we study both the problems of VNF placement and Routing/Spectrum Allocation (RSA) for inter-DC EONs with the aim of minimizing the total network cost while considering the balanced resource utilization to reduce the blocking probability. We first formulate the problem as an Integer Linear Programming (ILP) to solve the problem exactly, and then propose a heuristic algorithm based on the resource-balancing and fragmentationaware solution to reduce the blocking probability. The simulation results verify that the proposed algorithm outperforms an existing algorithm.