Research And Improvement Of NAT Load Balance System

With the popularization of the wireless mobile communication, Mobile Internet as a newform on internet, is becoming a driving force for the internet. With the convenience, open andidentity recognition of mobile app, mobile internet is providing a new development space andbusiness model for the internet. Meanwhile, the development of mobile internet has producedlots of new forms of application like webpage based on mobile, file download, location basedservice, online games, mobile office and online payment etc. But with the business growing,server side concurrent processing grows bigger too. However, the service is becoming slowerand slower because of defect of hardware architecture or low availability of some resources.In order to solve performance bottlenecks on server side, the load balance system isproposed in this paper. The system need to be deployed on sever, data base, storage and evenclient application. In order to solve the single server problems in load balance system, thispaper designed server-backup method to ensure the high availability of the whole system.Also this paper optimize the traditional NAT load balance method to make the best of thebandwidth usage.The research work mainly includes the following points:(1) Optimization of the NAT load balance architecture. The paper designed a singledispatcher server, multiple real server. Real servers get a ip alias which is the same ip addresson dispatcher server. In another word, each real servers has two ip address, one is the real ipaddress, another is the same with dispatcher server. The real server is also needed to ignore allthe ARP broadcast to public ip, so when the ARP asks which mac addrees has the public ip, only dispatcher server will response, the request will not directly reach the real server.(2) Improvement of the traditional one-to-many MySQL replication architecture. Tosolve the single server problem during mysql replication process, we add a back up server,when the request is written to local server disk, the request is also sent to a remote server andwritten in the disk. Master server synchronize with the backup server. When the master servergets problem, the remote server can be used. The data on master server will also be replicatedto many other slave servers, so these data can be read on these slave server, database readfunction and write function are independent.(3) To solve the single server problem of the traditional distributed storage system, thispaper put the log directory on single disk on master server, and deploy two envionment of thesame, set synchronization of the same block disk and log storage device.(4) A prototype system based on load balance architecture is designed and implemented.Moreover, in terms of the application background of picture sharing system. The paper madea experiment on server side picture reading. The experimental results show that the loadbalance architecture in this paper are superior to the NAT balance architecture in the case ofbandwidth usage.(5) Design a request repost on client side. We set a time limit on client side, if clientdosen’t get the right response with the time limit, it will repost another request to the backupdomain to avoid problem.Research shows that compared with the NAT load balance architecture, the optimizedload balance architecture make the better of the bandwidth usage, on the other hand, eachmodule achieved high availability.