Delay-Aware VNF Scheduling: A Reinforcement Learning Approach With Variable Action Set

Abstract

Software defined networking (SDN) and network function virtualization (NFV) are the key enabling technologies for service customization in next generation networks to support various applications. In such a circumstance, virtual network function (VNF) scheduling plays an essential role in enhancing resource utilization and achieving better quality-of-service (QoS). In this paper, the VNF scheduling problem is investigated to minimize the makespan (i.e., overall completion time) of all services, while satisfying their different end-to-end (E2E) delay requirements. The problem is formulated as a mixed integer linear program (MILP) which is NP-hard with exponentially increasing computational complexity as the network size expands. To solve the MILP with high efficiency and accuracy, the original problem is reformulated as a Markov decision process (MDP) problem with variable action set. Then, a reinforcement learning (RL) algorithm is developed to learn the best scheduling policy by continuously interacting with the network environment. The proposed learning algorithm determines the variable action set at each decision-making state and captures different execution time of the actions. The reward function in the proposed algorithm is carefully designed to realize delay-aware VNF scheduling. Simulation results are presented to demonstrate the convergence and high accuracy of the proposed approach against other benchmark algorithms.