Network Service Scheduling With Resource Sharing and Preemption

Network function virtualization enables network operators to implement network functions in a software-oriented manner and makes network services (NSes) provisioning much simpler. This paper proposes an optimization model to schedule delay sensitive NSes with deadlines allowing resource sharing and preemption. Unlike conventional NS scheduling models with static resource allocation for virtualized network function (VNF) instances, the proposed model ensures that VNF instances deployed on the same node share computation resources of the node and are able to scale up/down to change their process rate at runtime. NSes mapped to the same VNF instance of the same node share computation resources of the VNF instance and are able to be processed in parallel by the VNF instance. Preemption is allowed, which means that rescheduling the order of NS processing at runtime is possible and the process duration of each function of an NS is allowed to be discrete. We formulate the proposed model as an integer linear programming problem to maximize the number of admissible NSes. Due to the complexity of the problem, we develop a genetic algorithm to solve it efficiently. We evaluate the proposed model with conventional models in the static and dynamic scenarios. The numerical results show that the proposed model outperforms conventional models in terms of acceptance ratio in both static and dynamic scenarios.