AoI Aware VNF Scheduling with Parallel Transmission for Delay-Sensitive Applications.

For delay-sensitive network services, Age of Information (AoI) is appropriate to represent the freshness of information. Meanwhile, with the joint development of Network Function Virtualization (NFV) and Software Defined Network (SDN) technology, these network services can be managed as Service Function Chains (SFCs), composed of a collection of Virtual Network Functions (VNFs). Because the standard SFC architectures have been challenging to accommodate the low AoI demand for information in new scenarios like the Industrial Internet of Things (IIoT) and telemedicine, new SFC structures are constantly being proposed. In this paper, AoI is minimized by utilizing parallel paths to forward data between VNF instances. We formulate it as an Integer Linear Programming (ILP) problem. Moreover, a heuristic algorithm based on Particle Swarm Optimization (PSO) is proposed to solve it in large-scale networks. According to the simulation results analysis, our strategy can reduce the overall AoI of flows by at least 15% when compared to the conventional SFC architectures.