The Research On Load Balancing Technology Of Server Cluster Based On OPNET

With the rapid development of Internet and explosive increase of web application, the load of server and the visit requests grow exponentially,which makes a higher demand on server’s ability to respond to the requests and deal with them. As the memory,CPU processing speed and operating systems of the server are limited,the single server cann’t satisfy the demand for the increasing network traffic.In order to raise the availability of single server and avoid overload, the load balancing technology of sever cluster is an effective solution.Load balancing technology has many existing ways of transmitting data and some common scheduling algorithms, such as Round Robin Scheduling、Weighted Round Robin Scheduling、Least-Connection Scheduling、Weighted Least-Connection Scheduling and so on.But these algorithms have some deficiency,such as the load defined inaccurately,the weight is static and so, the article aims at the deficiency of existing load balancing algorithms and make the following researches:1. Discusses the significance of load balancing technology of server cluster,and summarize the development status of the technology of cluster and load balancing;2. Make a deep research of the load balancing technology of cluster, especially three existing ways of transmitting data in the IP layer and the classical load balancing algorithms, and analyze the disadvantages and advantages of these algorithms.3. On the basis of the above study,make a research of main function of each module by the NAT way in the IP layer, analyze some of the major factors which have effect one the performance of load balancing algorithm,and aiming at the deficiency of the common load balancing algorithms,this article puts forward a new load balancing algorithm——Adaptive Weighted Least-Load Algorithm(short for "AWLL"),that is,take different strategy according to the load of each server,and combine the server performance indicators with the number of connections to represent the load of server more accurately,which improve the efficiency and precision of the load balancing algorithm.Moreover,cluster system adjusts the weight of the server dynamically according to the load of each server, and schedule the load in accordance with the weight to make sure that the load of the server cluster is balanced.4. Designe each step of the AWLL algorithm in the process domain in the OPNET Modeler network simulation platform, model the network topology respectively from three levels which is network domain, node domain and process domain, and compare the classical algorithms with the new AWLL algorithm in the same environment.The results show that the service latency reduces greatly by using the AWLL load balancing algorithm, the server load keeps in a relatively stable state, and the utilization of the server resource increases obviously.It reveals that the AWLL algorithm works efficiently and reliabilitily to some extent.