Research On Multi-path Routing And Virtual Node Redundancy Of Reliable Service Function Chain

The widespread use of Cloud Computing,Big Data,Artificial Intelligence and other emerging technologies brings great challenges to the Internet infrastructure,promoting the appearance of Network Function Virtualization(NFV).In NFV,a network service is built by a set of VNFs concatenated in a given order,called Service Function Chain(SFC).The failures of physical links,servers and VNFs can all influence the reliability of a deployed SFC,leading to degradation of service satisfaction and revenue loss.Currently,redundancy is a de-facto technique to mask failures,however,it introduces extra resource cost.Hence,how to guarantee the reliability demand of an SFC with the minimum resource consumption is the main challenge of it.This paper decomposes this problem into two complementary sub-problems,multi-path mapping of virtual links and redundancy backup of virtual nodes of SFCs.Through comprehensive investigation and in-depth study,we made following contributions:(1)We propose multi-path mapping strategy to guarantee the reliability of SFCs against the failures of substrate link,model the problem as an Integer Non-Linear Programming(INLP)problem with the objective of minimizing the embedding cost of all SFC requests,and come up with the solution Availability-Guaranteed Embedding of SFC(AGES)algorithm.The multi-path mapping strategy aims to map each virtual link of an SFC to several physical paths uniformly so as to reduce backup bandwidth by making use of path splitting supported by substrate network.The final simulation results validate the advantages of AGES with respect to reliability guarantee,embedding cost,backup ratio and other metrics.(2)We propose VNF-node shared backup strategy to guarantee the reliability of SFCs against the failures of node and VNF,model the problem as an Integer Linear Programming problem(ILP)with optimization objective of minimizing the deployment cost of all SFC requests,and provide two solutions,algorithms of Primary Mapping of an SFC(PM)and Cost-efficient SFC Provision for Reliability(CSPR).in CSPR,backup node selection strategy based on node reliability and backup cost evaluation,and the reliability evaluation model of an SFC with backups based on the reliability matrix of backup nodes are proposed.Finally,the experiment results validate the effectiveness of the above algorithms with respect to reliability improvement of SFCs and resource consumption reduction.