Flash Crowd Mitigation System

Flash crowd means that a web server suffers a sudden surge of traffic since a large number of Internet users access the web server simultaneously. Once a flash crowd occurs in a web server, the response rate for the HTTP requests decreases rapidly, or the web server may even crash. To protect the web server from such flash crowds, in this paper, we propose the Flash Crowd Mitigation System (FCMS) which is based on the cooperation of the web servers and the redirection of the HTTP request. In FCMS, when a flash crowd is predicted by the traffic monitoring module in the router which is connected to the web server, other web servers replicate the hot server's contents, and then the router redirects the HTTP request to other web servers in order to alleviate the effect of the flash crowd. The simulation with real-world flash crowd traces shows that the monitoring module can predict the flash crowd and release the system from the flash crowd mode effectively. Also, our experiment in our testbed demonstrates that an implemented FCMS and our mechanism can work correctly and mitigate the effect of flash crowds in a web server.