Research And Implementation Of A Zero-Copy-Based Packet Capture Mechanism Under High_speed Network Environment

With the rapid development of the internet link speed, packet capture systems with high performance become more and more popular. In order to improve the I/O efficiency and lighten the load of the CPU in servers, the high performance packet capture systems use Zero-Copy mechanism to communicate with network. ZBM model is the functional unit to implement the Zero-Copy mechanism. It is used to exchange data between the application and the NIC Driver. Meanwhile, it answers for receiving data and releasing packet buffers.The main work and contributions of the dissertation are:(1) The processes of capturing packets based on Zero-Copy mechanism are analyzed in details and the cores of packet capture system: the Zero-Copy mechanism and protocol analysis mechanism with multithreading are introduced clearly.(2) Aiming at the problem of "receive livelock", a solution is proposed from the design of the packet capture system based on Zero-Copy.(3) The abstract models of the packet capture processes in the system are presented. The concept of Zero-Copy receiving stop is presented. Basing on this, the quantitative relationship among the parameters which impact the performance of packet capture system are analyzed.(4) The implementation of packet capture sytem based on Zero-Copy is introduced. Experimental results show that the design of the packet capture sytem is correct and effective.(5) The packet capture system based on multi_process mechanism is presented. Through this way the receiving performance of the packet capture system is improved.