Dynamic Resource Scaling for VNF Over Nonstationary Traffic: A Learning Approach

Software defined networking (SDN) and network function virtualization (NFV) are key enablers for service-level customized network slicing in fifth generation (5G) core networks. Network slices are required to be isolated from each other in terms of service performance with traffic load fluctuations. In this article, the virtual network function (VNF) scalability issue is studied to meet the quality-of-service (QoS) requirement in the presence of nonstationary traffic, through joint VNF migration and resource scaling. A traffic parameter learning method based on change point detection and Gaussian process regression (GPR) is proposed, to learn traffic parameters in a fractional Brownian motion (fBm) traffic model for each stationary traffic segment within a nonstationary traffic trace. Then, the time-varying VNF resource demand is predicted from the learned traffic parameters based on an fBm resource provisioning model. With the detected change points and predicted resource demands, a VNF migration problem is formulated as a Markov decision process (MDP) with variable-length decision epochs, to maximize the long-term reward integrating load balancing, migration cost, and resource overloading penalty. A penalty-aware deep Q-learning algorithm is proposed to incorporate awareness of resource overloading penalty, with improved performance over benchmarks in terms of training loss reduction and cumulative reward maximization.