Research On Guaranteeing Real-time Data Transfer In Internet

The Internet is regarded as the basic communication infrastructure for the new generation of information technology,e.g.,Internet of Things,Industrial Internet,big data,etc.The delay feature of Internet characterizes the information dissemina-tion in Internet and is a key performance index to evaluate the Internet.Recently,with the rapid development of new generation of computing technology,e.g.,high-performance cluster computing,cloud computing,edge computing/fog computing,etc.,the timeliness issue of the computing and development towards Internet ser-vice has been gradually transformed to the real-time data transfer issue in Internet,i.e.,the delay issue.Developed up to now,the Internet has gradually shifted from the original'space grab' mode to the 'time saving' mode.Research on infrastruc-ture and communication principles of the Internet towards real-time data transfer in Internet is of great significance for improving the efficiency of network resource utilization and service scheduling,and guaranteeing the real-time deployment of In-ternet service.This dissertation focuses on the delay issue in Internet and conducts the research on guaranteeing mechanism enabling real-time data transfer.With this researching target,this dissertation is carried out from the following aspects:delay detection,delay management and delay control.Firstly,an in-depth study about the delay detection issue in Internet is con-ducted,i.e.,characterizing the current delay in Internet.Based on the large-scale IPv4-level sample authorized by CAIDA,more than 9 million efficient detecting paths are extracted,and the analysis of the features of end-to-end delay in Internet and the evolutionary trends in time domain under Internet macroscopic topology is performed.It is found that the weak correlation between the end-to-end delay and the number of router the detecting packet traverses(i.e.,the hops),and the end-to-end delay is dominated by the delay of one or several links along the efficient detecting path.It is also remarkable that the bottleneck-delay defined in this dis-sertation appears in 70%of the efficient detecting paths,which is considered to have a strong impact on end-to-end delay.To further study the features of bottleneck-delay,an IP united mapping scheme which combines the IP centralized mapping with the IP geographic mapping is proposed.Statistical results show that two ends of a bottleneck-link are usually located in the same country(with probability 80%),and the links with a large number of entrances(in-degrees)and few number of exits(out-degrees)or the average shallower links are prone to leading to bottleneck-delays.At last,a deep discussion about the factor of bottleneck-delay is given,which demonstrates queuing delay is the key factor of bottleneck-delay mapped in the same country and propagation delay is the major component of bottleneck-delay for the long-range link.Afterwards,a new traffic scheduling engine DTE-SDN towards delay-sensitive traffic in Internet is proposed.DTE-SDN is dedicated to lead-ing to a delay management platform(including network resource manage-ment,equipment integration,traffic engineering(TE))that can guaran-tee the real-time data transfer in Internet.DTE-SDN utilizes the fea-tures of Software-Defined Networking technique with OpenFlow protocol(e.g.,Port_Status-Request?Port_Status_Reply?Packet_In?Packet_Out)to capture an overall view of the network and provides the ability of actively QoS metrics(e.g.,network link-delay,throughput)monitoring in real-time.To efficiently schedule the delay-sensitive traffic,a dynamic TE scheme capable of multi-routing is proposed to be deployed on the scheduling module of DTE-SDN,which allows DTE-SDN to compute the optimal TE strategy based on the instantaneous QoS metrics.Particu-larly,the TE issues can be addressed by addressing a proposed maximum flow over time issue based on time-expanded network,which can lead to a pseudo-polynomial algorithm.Furthermore,to distribute the traffic(especially for the UDP flow)a-mong multiple end-to-end paths and deploy TE,an improved group table module with probabilistic-matching technique of OpenFlow is proposed to be deployed in networking forwarding elements.Experimental results demonstrate that the pro-posed DTE-SDN is able to measure the throughput and delay under acceptable error range and can dramatically enhance the transfer efficiency than the tradition-al scheduling(e.g.,the scheduling based on shortest-path routing approaches or the maximum flow issues).Finally,this dissertation takes a deep discussion about the Multi-service Delay-constrained Transfer Scheduling(MDTS)issue.MDTS considers a delay control scenario where multiple flows related to different kinds of Internet service concur-rently require for real-time data transfer scheduling,i.e.,all the data transfers are confined to be completed within a time constraint.Based on the complexity proof for the MDTS issue,two static scheduling approaches(MDTS-R,MDTS-P)and a dynamic scheduling approach(MDTS-H)are proposed respectively,both of which are based on multi-path routing and flows over time technique.Particularly,MDTS-R utilizes maximum flow over time theory to address the flow optimization issue and is based on the single-service heuristic,while MDTS-P is derived from solving a pro-posed maximum constrained flow over time problem and optimizes the multi-service flow from the overall.MDTS-H makes use of maximum multi-commodity flow over time theory to greedily optimize the network flow on the whole,until a service's transfer is completed,leading to a new rescheduling.Especially in MDTS-H,the auxiliary-matrix is adopted for addressing the residual-flow issue during reschedul-ing,such that the minimum switching time(the time to reschedule)can be accu-rately computed.The simulational results demonstrate that,both of the proposed algorithms can address the MDTS issue in Internet.Especially,MDTS-R runs the fastest,MDTS-P is more efficient when the number of service is little.MDTS-H benefits from the dynamic rescheduling scheme and is more dedicated to addressing the MDTS issue with large number of service.