Research Of Campus Network Billing System Based On Soft Interrupt Request

With the popularization and development of campus network, many kind of accounting systems have been designed to guarantee the operation of it. And the technologies used in it have changed gradually, especially the method of flow collecting.In this thesis, a kind of accounting system based on transparent gateway was designed and finished which has some merits, for example, user-based, user-transparence and quick forwarding speed and so on. The integrated IP packet can be caught by the transparent gateway, so the accounting system can not only billing network usage by a person but also controlling the action of user and monitoring network performance. In the process of system design, all functions are coded with modularization, allmodules are integrated into system after strict test. The functions that have implemented include user authentication, collection and accounting of data flow, Kernel mapping, User-based billing system, System management. In order to solving the problem of performance bottleneck on gateway, we adopt various advanced and ripen technologies. Frist such as core performing in kernel space. Then enable user to comporarily stored in the kernel. Such an approach billing system greatly reduced the number of access to the databases, and try to avoid bottlenecks of system. Second, Double Buffering queue technologies, to enhance the kernel space for data read speed. Third, Soft interrupt request to capture data packets to improve the accuracy of catching packet rate and packet-capturing speed. Fourth, An adaptive polling daemon to avoid interrupt livelock.Finally, the system was tested, we found some probles and the timely correction. From the result of test and application, it proves that the system operates stable, billing for flow is accurate and well real-timed, access control and security mechanism for packet filtering is well operated, also it is convenient for user administration.