Optimizing NFV Chain Deployment in Software-Defined Cellular Core

Today's cellular core relies on a few expensive and dedicated hardware racks to connect the radio access network and the egress point to the Internet, which are geographically placed at fixed locations and use the specific routing policies. This inelastic architecture fundamentally leads to increased capital and operating expenses, poor application performance and slow evolution. The emerging paradigm of Network Function Virtualization (NFV) and Software Defined Networking (SDN) bring new opportunities for cellular networks, which makes it possible to flexibly deploy service chains on commodity servers and fine-grained control the routing policies in a centralized way. We present a two-stage optimization framework Plutus. The network-level optimization aims to minimize the service chain deployment cost, while the server-level optimization requires to determine which Virtualized Network Function (VNF) should be deployed onto which CPU core to balance the CPU processing capability. We formulate these two problems as two optimization programs and prove their hardness. Based on parallel multi-block ADMM, we propose a (δ, 2)-bicriteria approximation algorithm and a learning-based algorithm to address two cases whether the flow information and the resource consumption can be known as a priori, respectively. Large-scale simulations and DPDK-based OpenNetVM platform show that Plutus can reduce the capital cost by 84% and increase the throughput by 36% on average.