Enhancing the Reliability of Services in NFV with the Cost-Efficient Redundancy Scheme

Network Function Virtualization (NFV) transforms the traditional service provision architecture into a software-based structure. In NFV, Virtual Network Functions Forwarding Graph (VNF FG) [1] is used to describe the logic connections among the VNFs placed on the Physical Network (PN). And end-to-end services are represented as flows traverse the VNF FG. To improve the reliability of the services, redundancy is proposed as an effective method. Existing redundancy method protects the unreliable VNF for end-to-end service independently and embeds the backup without considering the reliability of the PN hardware. Such a scheme ignores the global information of the VNF FG and leads to an inaccurate reliability estimation for the services. These deficiencies result in over backup and the utilization reduction of the underlying resource. To overcome these shortcomings, we propose a novel redundancy scheme. By using the Cost-aware Importance Measure (CIM), the structure of the VNF FG is involved in selecting the qualified backups. Meanwhile, with CIM, the placement decision is made by mapping these backups to the PN nodes with high reliability. In our simulation, our method performs well for cutting down the backup cost for up to 46% with respect to the present algorithms and keeping high cost-efficiency.