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题名	分布式NAT穿越技术研究与实现
作者	严刚
学位类别	博士
答辩日期	2009-05-27
授予单位	中国科学院声学研究所
授予地点	声学研究所
关键词	NAT穿越 智能节点重叠网 会话层模块 节点选择 动态切换
其他题名	Distributed NAT traversal technology research and implementation
学位专业	信号与信息处理
中文摘要	随着互联网的迅速发展和NAT的普及，NAT穿越成为研究的热点。传统的穿越方案需要借助中央服务器或者修改NAT设备，可扩展性差。Skype采用分布式的穿越方式，可扩展性高，但它是私有应用，开放性和互通性差。 基于这种情况，本文在分析比较了已有穿越方案后，在智能节点重叠网服务平台上，提出并实现了虚拟公网分布式NAT穿越平台VPN-DNATT（Virtual Public Network-Distributed NAT Traverse），并对该平台的体系结构、功能架构和详细流程等进行了深入分析，主要的研究工作和创新有以下几个方面： (1)提出了虚拟公网和虚拟主机的概念，所有基于VPN-DNATT平台的应用对外呈现具有公网地址的虚拟主机，虚拟主机互联形成虚拟公网； (2)针对P2P应用的特点，根据NAT类型选择NAT穿越方案，创建相应的虚拟主机并绑定恰当的公网地址，针对各种情况选择有效的NAT穿越方案； (3)设计并实现了会话层模块，该模块位于传输层与应用层之间，向应用层隐藏NAT穿越的细节，提供统一开放的API接口，使VPN-DNATT平台开放性通用性强； (4)针对VPN-DNATT中的节点选择，提出了基于服务性能综合权值的最优选择算法，选出综合性能最佳的超级节点转发数据，保障了应用的QoS；从理论和仿真实验两方面证明该算法具有较高的性能； (5)针对网络动态性，提出了一种超级节点动态切换机制，既保障了应用QoS又均衡化了系统负载；从理论上分析了该机制的有效性和可行性； 最后通过网络实验测试，证明了VPN-DNATT平台NAT穿越的可行性和有效性。
英文摘要	With the pervasive development of the Internet and the popularity of NAT technologies, NAT Traversal has received a lot of research attentions. Due to rely on central servers and/or require changes on NAT devices, traditional NAT traversal methods have low scalability. By using distributed traversal methods, high scalability can be achieved by methods such as Skype, but usually these methods are proprietary, leading to low interoperability. In this thesis, we develop a new design method called virtual public network-distributed NAT traversal (VPN-DNATT), which is based on the existing traversal methods and the service platform called Intelligent Node Overlay Network (INON) system. The contributions made in this work are as follows: 1) We propose the concepts of virtual host and virtual public network. All applications based on VPN-DNATT platform can be treated as a virtual host carrying an addressable public address, which can be seen by others in the Internet. All virtual hosts can communicate with each other to form a virtual public network. 2) To utilize P2P features, the proposed VPN-DNATT platform can select the most effective traversal method according to the NAT type, and it can create the corresponding virtual host and bind appropriate public address with the virtual host. 3) A session module between transport and application layers has been designed and implemented. The session module can hide the details of NAT traversal at the application layer, and provide a uniform and open API which makes VPN-DNATT an open and interchangeable platform. 4) We propose an optimal node selection algorithm for VPN-DNATT based on the service performance, which can select a super node with the best performance. Thus, it can guarantee the application QoS. The feasibility and effectiveness of the proposed algorithm has bee theoretically analyzed and experimentally verified. 5) We propose a super node adaptation algorithm to accommodate the network dynamics and to guarantee the application QoS as well as balance the network load. The feasibility and effectiveness of the proposed algorithm has been theoretically analyzed. 6) We have validated the feasibility and effectiveness of the proposed NAT traversal based on the VPN-DNATT platform through experiments.
语种	中文
公开日期	2011-05-07
页码	73
内容类型	学位论文
源URL	[http://159.226.59.140/handle/311008/570]
专题	声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文
推荐引用方式 GB/T 7714	严刚. 分布式NAT穿越技术研究与实现[D]. 声学研究所. 中国科学院声学研究所. 2009.

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