移动互联网环境下SIP穿越NAT的研究

Research of NAT Traversal for SIP under Mobile Internet Environment

摘要: NAT (Network Address Translation)穿越问题是制约SIP(Session Initiation Protocol)发展的主要障碍之一。分析了ICE(Interactive Connectivity Establishment)方式协助SIP穿越NAT的机制，并根据移动互联网环境的特点对ICE作了进一步改进，最后把改进的ICE作为一个模块成功嵌入到了Android VoIP软件之中。实验证明改进的ICE可使SIP穿越任何NAT，且有成功率高、低时延的优点，非常适用于移动互联网环境。

Abstract: NAT (Network Address Translation) traversal is one of the main obstacles restricting the development of SIP(Session Initiation Protocol).By analyzing the ICE (Interactive Connectivity Establishment) method for SIP operating through NAT and the characteristics of the mobile Internet environment,some further improvements are made to the ICE.Finally,the improved ICE is embedded as a module into an Android VoIP software successfully. Experiments show that the improved ICE allows SIP to operate through all kinds of NAT with a high success rate and low delay,and it is ideally suited to the mobile Internet environment.