Service Function Chain Deployment with Guaranteed Resilience

Abstract

Network Function Virtualization (NFV) transforms the implementation of network functions from expensive hardwares to software middleboxes. These software middleboxes, also called Virtual Network Functions (VNFs), are executed on virtualization platforms, which makes them more prone to error compared to dedicated hardwares. One effective way of ensuring VNF robustness is to provision redundancy in the form of deploying backup instances. Flows usually request to be processed by a service chain, consisting of multiple chained VNFs in some order. This paper considers both the resilient VNF deployment and the routing of flows. We deploy both active and backup VNF instances while guaranteeing the required VNF service resilience. Our objective is to minimize the total expected transmission delay of all flows when the probabilistic prior failure information is given. We first formulate our problem mathematically. We discuss the solution for the general network setting. Then, we simplify some setups and propose performance-guaranteed solutions in various scenarios with detailed approximation ratio analysis: for the case of a single flow without backup instances, we propose four optimal solutions corresponding to the settings of link transmission delay and server capacity; for the case of a single flow with backup instances, we extend the algorithms; for the case of two flows without backup instances, we propose efficient algorithms with approximation ratios inspired by the solutions for a single flow.