Reliability-oriented Service Function Chain Consturction And Backup Method In NFV

Network Function Virtualization(NFV)is considered to be an important way for network transformation of operators.NFV decouples network functions from proprietary hardware,enabling network functions to be deployed on standard servers and virtual machines,reducing operator costs and increasing the flexibility of network service deployment and switching.In NFV environment,Service Function Chain(SFC)defines the link order of virtual network functions required in Service requests.The network operator maps the SFC to the physical network to provide corresponding services for users.Although NFV-based SFC can provide services more conveniently,network services may also be interrupted due to software and hardware failures.In order to provide users with stable services,how to ensure the reliability of SFC is a key issue in NFV research.The deployment of network services in an NFV environment is a process of resource allocation,generally divided into three phases:construction,mapping and adjustment,in which network functions and infrastructure networks affect the reliability of the SFC.According to the work in each stage,taking reliability as the direction of optimization can make the SFC meet the requirement of reliability before the final operation.There are few studies on the construction phase in the existing literatures,while they don't discuss much about reliability.Many researches have carried out work in the adjustment phase,using various backup methods to improve reliability,but resource consumption is excessive.This paper focuses on the reliability issues involved in the construction and adjustment phases,and studies the NFV-based SFC construction and backup methods,including:(1)An SFC construction method based on instance sharing and reliability is proposed.This method considers the dependency factor when linking instances in SFC and determines the order of instances in SFC by quantifying the dependency level of instances.Considering the factor of instance sharing,the Service Function Graph(SFG)set is generated when multiple SFCS are constituted.Finally,the SFG in the set is screened by the algorithm of Ordered Binary Decision Diagram to minimize the influence of the software reliability of VNF instance on the service.(2)An SFC backup method based on node centrality and reliability ranking is proposed.This method performs backup processing for SFCs that do not meet the reliability requirements after mapping.The method mainly includes two processes:backup node selection and backup instance deployment.This paper uses centrality and reliability to design a heuristic algorithm to select nodes that need to add backup instances and uses a physical node selection algorithm based on width-first search to deploy a backup instance and build a relevant backup path.To sum up,this paper proposes and designs a reliability-based SFC construction and backup method,which can reduce node resources and backup bandwidth resources consumption in the construction and backup process and improve the acceptance rate of SFC on the premise of ensuring the reliability of SFC.