|
VoIP(Voice over IP) includes a set of protocols and technologies such as SIP, SDP, H.323, which challenges the traditional PSTN telephony with its powerful functions, cheap price and obvious facility. VoIP not only support voice, but also support video, data and fax. However, many private networks use a NAT device, the flow of the signaling and media streams into and out have a lot of restrictions and limitations, if not properly circumvent these constraints, you can not engage in normal communication.This article on the issue, as well as several mainstream thingking of the solution are introduced, and made the solution more flexible than the current NAT traversing and efficient solutions. This article first introduce VoIP technology in detail, and then introduced the NAT technology, the relevant background and analysis of the current number of NAT and their typical characteristics. Analysis of the current mature and business NAT traversing solutions, and given the advantages and disadvantages of each solution, and finally put forward a new solution of traversing all kinds of NAT, and introduce the working flow of new solution.According to work’s principle of solution, the module design of SIP terminal has been given. The modules of SIP terminal include the SIP protocol module, the NAT examination module, the relay module, the mapping maintenance module, the media traversing module, the media processing module are designed.The system has been tested under different network environment to proof the correctness of the solution, all the tests have been get the desired results.
|