基于ICE方式SIP穿透Symmetric NAT技术研究

Study on methodology for SIP traversing symmetric NAT based on interactive connectivity establishment

基于IP的语音、数据、视频等业务在NGN网络中所面临的一个实际困难就是如何有效地穿透各种NAT的问题。对此,会话初始化协议SIP以往的解决方法有ALGs、STUN、TURN等方式,但它们都具有一定的局限性。探讨了一种新的媒体会话信令穿透NAT的解决方案——交互式连通建立方式(ICE)。它通过综合利用现有协议,以一种更有效的方式来组织会话建立过程,使之在不增加任何延迟的同时,比STUN等单一协议解决NAT穿透问题更具有健壮性、灵活性。详细介绍了ICE算法流程,并设计一个实例针对SIP信令协议穿透SymmetricNAT流程进行了描述,最后总结ICE的优势及应用前景。

A methodology for Network Address Translator （NAT） traversal for multimedia session signaling protocols, such as the Session Initiation Protocol （SIP） was described. This methodology is called Interactive Connectivity Establishment （ICE）. ICE is not a new protocol, but rather makes use of existing protocols, such as Simple Traversal of UDP Through NAT （STUN）, Traversal Using Relay NAT （TURN）. ICE works through the mutual cooperation of both endpoints in a session. The article describes ICE algorithm was described in and designs an example of that ICE traversal through Symmetric NAT was given.