Design And Implementation Of CAPWAP Multicast

With the rapid development and expansion of wireless Local Area Network, the cellular architecture (traditional WLAN architecture) has given way to the centralized wireless network architecture. The protocol of centralized wireless network architecture is gradually getting matured along with the increasing maturation of network architecture. The IETF group published CAPWAP protocol (Control and Provisioning of Wireless Access Point), which was defined as the international standard April 4th, 2009. Meanwhile, network application such as audio and video service which has to use the technology of multicast is occupying the more and more proportion now, thus, it is imperative for us to research and develop the technology of multicast in CAPWAP protocol.In this paper, we investigate on the solution of CAPWAP architecture and the principle of multicast.We proposed three available approaches and compared each of them according to the system environment and requirement of the company. When AC received multicast messages, it capsulate all of them and send them through an outer layer tunnel. The multicast distribution tree between AP and AC is maintained by the Multicast Routing Maintenance Protocol. In this case, multicast message would be send only inside the multicast tunnel when they arrived AC. When multicast mode is enabled, only one copy of message is stored in AC, which can dramatically reduce the burdens of AC and network traffics.We will also briefly describe the scheme and method of system test. Besides, Analysis about problems occurred in real wireless local area network is stated. It turns out that the final system totally satisfying the original requirement. The CAPWAP protocol itself is stable and compatible. The technology of multicast makes it better by reducing the network traffics and improving the bandwidth utilization rate.