Research On The Optimal Lawful Intercept Access Points Placement Problem In Hybrid Software-Defined Networks

Lawful Interception(LI)is one of the main provisions needed for the Law Enforcement Agencies(LEAs)to intercept a suspect or deal with criminal activities.To implement lawful interception in traditional IP network,however,special equipment and links need to be set up,which is easy to practice but expensive.With the innovation of network technology and the continuous increase of network traffic,LI has become a difficult work.Due to the characteristics of software-defined network(SDN),such as separation of transfer control,centralized control and network programmability,the development of large-scale Internet oriented to software-defined has become a predictable industry trend.But the deployment of a pure SDN is not achieved overnight,thus forming a hybrid softwaredefined network(H-SDN)in which SDN nodes coexist with traditional nodes.This paper aims to contribute to the next generation of intelligent lawful interception technology in large-scale hybrid software-defined network using SDN technology for reference.In order to solve the problem of deploying lauful intercept access point in H-SDN,we put forward an improved equal-cost multi-path shortest path algorithm based on Dijkstra algorithm(ECMP-Dijkstra)and accordingly propose three SDN interception models(T,ECMP-T and Fermat-point)to deploy intercept access point(IAP)reasonably,and the algorithms of these models are in accordance with the time and space complexity.And then we compare and analyze the impact of three SDN interception models on the performance metrics of lawful interception system,thus to seek out the best SDN interception model which is Fermat-point interception model.In order to optimize the deployment of IAP,expand the deployment of multiple IAPs,we consider the location relevance of all intercepted targets and the operation and maintenance cost of operators from the global perspective,and then further propose a restrictive minimum vertex cover algorithm(RMVCA),which can achieve the maximum intercept link coverage of the whole network with the least SDN nodes and can optimize the deployment efficiency of multiple IAPs in the global network and improve the intercpt link coverage of the whole network.