Latency-Efficient VNF Deployment and Path Routing for Reliable Service Chain

Abstract

Network services usually chain multiple types of Virtual Network Functions (VNFs) together in a specific order, known as service chain. One important issue of providing network services is reliability, which means that each type of VNF in a service chain acts properly on its function. The effective way to guarantee the reliability is to utilize sufficient redundancy through providing VNF backup instances beyond active primary ones. Software Defined Networking (SDN) enables the dedicate location pickup of primary and backup instances on switch-connected servers. The deployment of primary and backup VNF instances plays an important role of flow routing because of its influence on the transmission latency of the flow. In order to minimize the total latency of flows, we first formulate the reliable service chain deployment as a mathematical optimization problem. A detailed analysis of both software and hardware failure models is studied. Then we propose optimal solutions for the case of a single flow. Next, we prove the NP-hardness of our problem for the case with multiple flows and propose a heuristic strategy. Additionally, a performance-guaranteed solution is included if the server capacity is infinite. Extensive simulations are conducted to evaluate our proposed solutions compared to multiple algorithms.