SAFE: Service Availability via Failure Elimination Through VNF Scaling

Abstract

Virtualized network functions (VNFs) enable software applications to replace traditional middleboxes, which is more flexible and scalable in the network service provision. This paper focuses on ensuring Service Availability via Failure Elimination (SAFE) using VNF scaling, that is, given the resource requirements of VNF instances, finding an optimal and robust instance consolidation strategy, which can recover from one instance failure quickly. To address the above problem, we present a framework based on rounding and dynamic programming. First, we discretize the range of resource requirements for VNF instances deployment into several sub-ranges, so that the number of instance types becomes a constant. Second, we further reduce the number of instance types by gathering several small instances into a bigger one. Third, we propose an algorithm built on dynamic programming to solve the instance consolidation problem with a limited number of instance types. We set up a testbed to profile the functional relationship between resource and throughput for different types of VNF instances, and conduct simulations to validate our theoretical results according to profiling results. The simulation results show that our algorithm outperforms the standby deployment model by 27.33% on average in terms of the number of servers required. Furthermore, SAFE has marginal overhead, around 7.22%, compared to instance consolidation strategy without VNF backup consideration.