一种SIP穿越NAT的新方法

NAT使得SIP端到端的通信变得非常困难,文章分析了几种SIP穿越NAT方法及其不足,提出了一种基于最短路径的NAT穿越方法SPNT(Shortest Path for NAT Traversal).其基本思想是根据SIP终端和代理服务器之间的信令交互,判断终端所在网络的NAT类型,代理服务器对不同的NAT类型采用不同的方式实现SIP信令穿越,而媒体流的穿越则通过终端进行媒体地址的连通性检测,使终端之间能够动态的建立最短的媒体数据连接.该方法在不改变现有NAT的情况下,在应用层实现了对所有NAT的有效穿越,避免了单独使用某一方法而带来的缺陷.

A New Solution to Traversal NAT Based on SIP

The NATs caused the SIP end-to-end application to become extremely difficult.In this paper we analyzed several kinds of method of NAT traversal for SIP and their pitfalls, proposed a solution SPNT(Shortes Path for NAT Traversal). The basic idea is that the proxy judges the NAT type which the SIP device is behind through the information interacting between the proxy and the SIP device, It takes different methodology to traverse the NAT by the NAT type for the SIP signaling, and the shortest associated media data path between the devices are dynamic established by the connectivity checks to the media addresses. This solution can traverse all NATs in the application layer not changing the existing NAT,and avoids the pitfalls of using any of the other methods alone.