基于SIP协议的网络地址穿越的设计

【作者】 李国才；

【导师】 侯孟书； 车艳军；

【作者基本信息】 电子科技大学 ， 软件工程， 2009， 硕士

【摘要】 IPv4地址的引入有其不可磨灭的进步意义。现有的互联网是在IPv4协议的基础上运行。但是IPv4定义的有限地址空间将被耗尽,地址空间的不足必将影响互联网的进一步发展。为了扩大地址空间,拟通过IPv6重新定义地址空间。然而由IPv4地址向IPv6地址的转换不是一蹴而就的。由于成本等多方面原因的限制,必定在很长一段时间内存在一个IPv4地址和IPv6地址共存的局面。为了解决IPv4地址不足的问题。目前NAT设备被大量的部署在网络中。NAT的存在一方面可以解决IPv4地址不足的问题,另一方面也可以对于私有网络起到屏蔽和保护的作用。SIP协议具有优异的可扩展性、与Internet紧密结合、卓越的开放性。它不仅能够对手机、PDA等移动设备提供良好的支持,对于在线即时交流、语音和视频数据传输等多媒体应用也能够很好地完成。因此,SIP协议在NGN中起着非常重要的作用。在我们的远程网络可视指挥系统中也是起着非常重要的作用。因此在目前的客观情况下,解决SIP协议的NAT穿越问题迫在眉睫。本文首先简述了SIP协议的基础知识、网络结构和消息格式等,然后调研了NAT技术的发展、NAT穿越的方案和国内外研究现状。在第四章和第五章中,分别阐述了UDP协议穿越NAT的策略和实现过程,以及TCP协议穿越对称型NAT的策略。这就支撑了构建于这两个传输层协议之上的SIP协议的NAT穿越平台。最后,本文研究和分析了SIP穿越NAT的方案,并举一例说明了SIP协议NAT穿越的可行性。更多还原

【Abstract】 The indelible advancement of IPv4 is known by all. Today’s Internet is just build on it. But the address space of IPv4 will be used up in the near future.The shortage of address space has been a hindrance of the development of the Internet. To expand the address space, IPv6 had been puted forward.Rome was not build in one day. Concerning the cost and other problems, it will be a long time we see both IPv4 and IPv6 exist in our life. A lot of NAT equipment had been disposed to solve the problem of shortage of addresses of IPv4. This equipment can also provide the shield and protection of the private LANs.SIP protocol has good expansibility, tight combination with Internet and preeminent opening. It can support mobile equipment like mobile phone and PDA and multimedia application like the transmission of audio and video data. So, SIP protocol plays a very important roll in the implement of NGN and in KSZH too. To solve the problem of SIP‘s NAT traversal is very urgent.Firstly, this thesis briefly describes the foundation, network architecture and message format of SIP protocol. Then we investigate the development of NAT, and research the existent methods and status in quo of NAT Traversal at home and abroad. In chapter 4 and chapter 5, we talked about how UDP protocol and TCP ptotocol traverse NAT to build a foundation for SIP’s NAT traversal. Further more, we discuss the problem concern with SIP’s NAT traversal and provide the solution to solve it.更多还原