Research On Virtual Network Function Placement And Migration Algorithm In The 5G Network Slice

The 5G network slicing technology based on network function virtualization(NFV)technology and software defined network(SDN)technology can create and divide different dedicated networks for different user services,which makes the networking mode of the whole network more flexible,and effectively solves many problems such as closed vertical of the existing network architecture to meet the needs of multiple 5G new services.NFV technology and SDN technology can be used to implement the network function of dedicated hardware through software-based virtualized network function(VNF).Different types of VNF are orchestrated according to specific rules to form the service function chains(SFC)which correspond to user services in order to provide exclusive services to users in different network slices.Therefore,how to place VNF and how to migrate it in the case of changing resource requirements of VNF to minimize operator costs and ensure network stability should be the focus of research.This paper focuses on the VNF placement problem and the VNF migration problem in the 5G network slice access side.The main research contents and innovation work of the paper are summarized as follows:1.Queue-aware Dynamic Placement of Virtual Network Functions Algorithm in the 5G Access NetworkDuring the VNF placement process in the 5G access network,a large number of various user service requests arrive in the network in a short time,which is likely to cause a backlog of user services and seriously affects the stability of the network.Aiming at the above problem,this paper firstly designs a dynamic scheduling model of two-stage queue to perceive the status of current queue backlog and schedule the queue dynamically.In particular,this paper formulates a VNF placement cost minimization problem,taking the network stability into account.Owing to that the problem belongs to an NP-hard problem,this paper transforms it into the minimization of the upper bound of the drift-plus-penalty function by the Lyapunov optimization technique.Then,this paper decomposes the reformulated problem into a SFC scheduling problem and a SFC mapping problem,corresponding to our designed dynamic scheduling model of two-stage queue.For the above mentioned two problems,this paper presents a queue-aware dynamic placement of virtual network functions algorithm.It includes a genetic algorithm-based heuristic SFC scheduling algorithm(first stage)and a genetic algorithm-based heuristic SFC mapping algorithm(second stage).Simulation results demonstrate that the placement algorithm can guarantee less placement cost while significantly enhancing network stability,compared with the existing algorithm.2.Multi-priority based Joint Optimization of Virtual Network Function Migration Cost and Network Energy Consumption Algorithm in the 5G Access NetworkAfter the VNF in the 5G access network is placed,the resource requirements are dynamically changed,resulting in the problem that the physical machine(PM)resource utilization in the network is too high or too low.Aiming at the above problem,this paper firstly divides the resource usage of PM in the network into five different partitions,and proposes a multi-priority VNF migration request queue scheduling model.Secondly,based on the model,a joint optimization model is established to minimize the VNF migration cost and minimize the network energy consumption,and the optimization model is further divided into three types of minimization sub-problems.Finally,a multi-priority based joint optimization of VNF migration cost and network energy consumption algorithm in the 5G access network is proposed to solve the above three sub-problems.The simulation results show that the algorithm can effectively realize a compromise between VNF migration cost and network energy consumption while ensuring the PM performance.Meanwhile,the algorithm can improve the PM resources utilization and balance the PM load.