Design Of Data Traffic Fast Forwarding In Centralized WLAN

As the Wireless LAN technology matures and its applications popularize, more and more enterprizes, schools and cities start large-scale deployment of WLAN, and the number of end users and wireless devices that access the wireless network have grown exponentially in size. In order to make the wireless network easier to be managed, monitored and maintained, the centralized WLAN architecture has gradually replaced the traditional autonomous WLAN architecture. However, in recent years, popularity of the IEEE802.11n high-speed wireless LAN has been making the data forwarding rate of the current centralized wireless LAN network difficult to keep up with the increasing requirement of the network throughput. With the number of mobile applications increase explosively, the centralized WLAN will face greater challenges.Based on the analysis of the data traffic forwarding mode in CAPWAP (Control And Provisioning of Wireless Access Point) protocol and data traffic features under different forwarding mode, several improvements for data traffic processing scheme in CAPWAP data tunnel under the current centralized forwarding mode is proposed. And a fast packet processing scheme that meets the requirement of rapid growth of data traffic in centralized WLAN is designed. It is based on the current mechanism of CAPWAP data packet processing and fast switching with cache. The time cost on data traffic processing is reduced by substitute preprocess in first packet processing in the tunnel for every process of frame conversion and CAPWAP encapsulation (or decapsulation). And also the processing efficiency is improved.Furthermore, based on the current centralized WLAN system and its forwarding model, a new data traffic forwarding model based on the zero-copy technology is proposed. In this model, information exchange between modules and redundant protocol handling process is removed. So the system performance on data traffic forwarding is improved by reducing packet copy frequency and time cost on protocol handling.Finally, the paper describes ideas and related methods to test the fast forwarding scheme for the centralized WLAN system, and then gives the performance test results of the new system. Test data show that network throughput can be increased a lot by applying the proposed fast-forwarding scheme. And the new system has been successfully applied in a variety of wireless access controllers. The data traffic fast forwarding scheme for the centralized WLAN in this research can also be easily ported to support centralized wireless network systems with tunneling technologies other than CAPWAP. So it has broad application prospects.