Research On The Reliability Of Service Function Chain In NFV

With the continuous development of the Internet and rapid changes in the requirements of network services,the disadvantages of traditional network have gradually emerged and it has been unable to meet the diversity and high quality service requirement of users.The emergence of Network Function Virtualization(NFV)technology provides an effective solution for the current serious problems of network hardware and software coupling.The software-based network functions in NFV can flexibly satisfy the user's network requests,but also bring a lot of challenges.Because NFV is based on the virtualization technology to realize the network function of the dedicated equipment on the commercial general equipment,it will bring the decline of reliability and other issues inevitably.Therefore,in the process of network service request processing,it is very important to ensure the reliability of network services.Supported by the National Natural Science Foundation Project "Virtual network adaptive management technology",this paper studies the problem of how to improve the reliability in the construction and processing of service function chain in NFV.First,how to construct a service function chain with higher reliability and lower resource consumption when responding to the requests of users.All kinds of network are composed of nodes and links,so is true of NFV.The service function chain which host the services is also made up of nodes and links.So the second and third chapters of this paper study how to improve the reliability when nodes and links fail,and reduce the resource consumption on the basis of reliability improvement.The main research work of this paper is as follows:A service function chain topology construction strategy with high reliability and low resource consumption is proposed based on the combination of virtual network functions to improve the reliability and reduce the resource consumption in NFV.First,the reliability of the service function chain can be improved by reducing the number of deployment nodes through the combination of the virtual network functions.However,the resource consumption of bandwidth may be increased because of changes in deployment nodes after the combination.Second,the game relationship between reliability and resource consumption caused by virtual network function combination is expounded,the network model is established,and a strategy of optimal service function chain topology construction is proposed based on the resource consumption of critical sub-topology mapping feedback.Finally,simulation results show that the proposed strategy can effectively improve the reliability of the service function chain.At the same time,the proposed method can save about 20% of the resource consumption compared to the non-feedback combination method with the same reliability.An optimal protection strategy for searching key virtual network functions and only adding their backups is proposed to solve the problem of excessive resource consumption in the protection of virtual network function fault in NFV.First,the problem of fault protection of virtual network function is expounded,and the reliability model is established,and the backup strategy of searching key virtual network function is proposed to solve it.Second,the critical virtual network function is selected by setting the evaluation criteria.Due to the different number of fault virtual network function nodes,two search algorithms are proposed respectively,and the key virtual network functions are selected for redundant backup to ensure the reliability of service function chain.Finally,simulation results show that the proposed strategy can improve the reliability effectively and minimize the consumption of resources by about 12% while guaranteeing the reliability,and maximize the rate of requests acceptance by about 11% compared with the GREP method.A strategy for adding and simplifying a backup topology is proposed to ensure the reliability with less resource consumption of single link failure in NFV environment.First,the process of service function chain is modeled.Second,the backup topology is introduced,and two optimal backup topology generation algorithms are proposed according to whether the service path can be separated.Finally,the experimental results show that the proposed strategy and the simplified algorithm consume less resources under the premise of improving the reliability of the service requirements.The maximum cost of resources can be saved by 7% compared with the I-S algorithm which has the same reliability.