Sip-based Voip Technology On The Campus Network

With the progress of science and technology, computers and the Internet has developed with surprising speed. Its influence has arrived in each domain, including educational field. Many schools have set up their own campus network. Voice over IP (VoIP) technique has been developed recently. It is to use the IP network to transpmit synchronous languages and voices and has many advantages such as small bandwidth, high resource utilization, low cost, etc., that is why it can be used globally. VoIP technology can not only be used in wan, but also provide all levels of service in campus network. Thus the existing education resources can be made better use, and school teachers can be provided better service. But because of the technical characteristics of VoIP itself, how audio and video data get through NAT and the firewall has become the focus of attention. This paper mainly has put forward the scheme of getting through tunnel by using it how to make data get through NAT and firewall, based on the implementation of network project of Zhengzhou Economy Trade School. This project has established two servers in Zhengzhou University and Zhengzhou Economy Trade School campus network, and built up the tunnel through which data get between them. At the same time, LZPT agreement was chosen as tunnel transmission control protocol. This agreement improves not only the data transmission rate, but also the security and reliability of data transmission. After verification, this scheme is proved feasible.The paper first analyzes the principle of VoIP, expounds the SIP protocol characteristics and development trend, introduces the concept of firewall and NAT, and the influence they have on transmission of audio and video data. Then the paper discusses various schemes, and the security problem VoIP network is facing. At last the paper mainly states the design and implementation process of network project of Zhengzhou Economy Trade School, and analyzes the flow of network data transmission. In the end, the paper expects the VoIP technical development trend and prospects.