Research On The Key Technologies Of Network Performance Optimization Based On Network Traffic Monitor And Control

Problems to be solved immediately in the modern network communication are the control of network congestion, optimization of network performance, and improvement of network service quality. In this dissertation, several major problems are studied to improve network performance in traffic control and network optimization, including the deployment optimization of monitor-nodes, performance analysis based on the traffic of multi-rate VBR services, traffic control based on call admission control, traffic control based on the coordination of branch routers and abnormal traffic control.The main work of this dissertation is as follows:1. Research on the optimization of network traffic monitoring model and its approximate algorithmThe cost of network traffic measurement includes test cost and cost of test station deployment. A key point to optimize network traffic monitoring model optimization is: firstly deploy measurement station is as less as possible to reduce the deployment cost, then optimize the distribution measurement plan to reduce the measurement cost, and improve the network performance. Under the traffic flow conservation law, we can reduce the problem of network traffic monitoring model optimization for finding the minimal weak vertex cover of a graph. Because the problem to find the minimal weak vertex cover of a graph is equivalent to an NP-hard problem,, an approximation algorithm is proposed based on the concept of incidence matrix in Graph for centralized network, the complexity of this algorithm has been analyzed, moreover, the algorithm is extended to seek the minimal weak vertex cover for a graph that has weights on the nodes. For the distributed network, the thesis presents an algorithm for finding the weak vertex cover of a graph, which does not require the information of the whole network topology. Analysis and experimental results show that this algorithm is more efficient and scalable than the traditional methods. The solution and approximate algorithm of traffic measurement assignment can be used to solve optimization problems of measurement delay, packet loss rate and other network performance parameters, which is meaningful to the design and implementation of the network measurement system.2. Network performance analysis based on real-time VBR business trafficA systematic research is made on the call level and packet level performance analysis in a system with multi-rate VBR traffic. For the resource partial-shared case, an algorithm is proposed to accurately evaluate the probability distribution of on-line connections of each traffic type according to the global balance condition of a multi-dimensional Markov chain. Furthermore, the call blocking probability and the packet loss probability are also obtained. Simulation results show that the algorithm is accurate. In addition, analysis has been done on the function relation between the service quality indicators such as the call blocking probability and the packet loss probability and their transmission control parameters. In the packet level, firstly we analyse the packet loss probability of the system in the case that the source sending rate is on-off style, then we study the random process model of the source sending rate of general real-time VBR traffic which is close to the actual situation, and propose a universal source model that each traffic’s source rate desirable for a multiple minimum rate (discrete integral times), and the theory calculation method of packet loss probability is presented. Several typical probability distributions of packet loss probability of source sending rate are analyzed and compared, Simulation test results show that the proposed method is valid.3. A traffic control scheme based on call admission controlThe implementation of a call admission control strategy is discussed for resource partial-shared systems with multi-rate VBR traffic. The strategy is dependent on the max bandwidth and the expected threshold of the cell loss probability. Both the relative theory analysis and verification are carried out. Another call admission control strategy is proposed for resource full-shared systems with multiple real time variable bit rate services. The strategy only needs dynamically adjust the capacity scaling factor and decides whether to admit a call on the base of the numbers of online service connections, the type of call requests, the product of capacity scaling factor, and physical capacity. A approach is presented to calculate the call blocking probability and the packet loss probability. The numerical results show that the proposed strategy could improve the throughput of the system.4. Traffic control scheme based on branch routersIn order to improve the capability of the whole network, a multicast flow control strategies is proposed based on the coordination of branch routers, which employs a new closed loop controller in every branch router to regulate the transmitting rate of senders for stabilization. In addition, those branch routers possess a certain number receivers to copy the needed data. If the retransmit-request packets are arrived from receivers in the given time, then they will send the copied data to those receivers again. Simulations are done in the case of network topologic structure dynamic variation. Experiment results show that the novel strategies has fairly good expansibility, stability, and response speed.5. A anomaly traffic control based on traffic analysisComprehensive analysis of telecom level IP network traffic was carried out with the help of traffic statistical analysis and deep packet analysis engine. A wideband service conduct analysis control system is designed based on network traffic and implemented in the paper. The system is proposed to interface with other systems such as IP network management system, security management system, and big customer system in the present telecom network to obtain incident response control. Strategies for network anomaly traffic detection and control are discussed, and the broadband service traffic direction and behavior characters in the large-scale telecom network are analyzed based on the data of traffic monitoring system. The network traffic analysis control system has been applied in the actual telecommunication networks, it supplies efficient analysis and management functions to business operations through competition defense, application service evaluation, customer service report and ICP business assessment, and promotes the profitability of Broadband telecommunications network.