Centralized approaches for virtual network function placement in SDN-enabled networks

Software-defined networking (SDN) and network function virtualization (NFV) represent significant changes to the architecture of data networks. SDN provides clean separation of the control plane from the data plane while NFV helps virtualize functions typically implemented using middleboxes into virtual network functions (VNFs). The network function placement (NFP) problem involves placing VNFs to satisfy the service function chaining (SFC) requests of the flows in the network. Current solutions to this problem are slow and cannot handle real-time requests. In this paper, a static NFP solution that uses a divide-and-conquer approach is discussed first, with complexity similar to that of existing solutions. It is shown that the solution is complete and sound. Next, customization of this solution to obtain an agile version that trades off precision for time complexity is discussed. A combination of this divide-and-conquer solution with a modified version of Dijkstra’s algorithm is used to solve the problem for dynamic requests. Finally, a centralized, online SDN-enabled approach to solving the problem is proposed. The proposed architecture and algorithms are simulated and analyzed with various system parameters and are shown to scale to large data center network (DCN) topologies.