空间通信需求的迅猛增长促使空间通信向网络化和天地一体化的方向不断发展.空间网络具有子网异构、网络拓扑不断变化、链路传输延迟大、链路误码率高等特点.TCP/IP网络协议族需要连续稳定的网络连接和较短的传输时延,空间网络不能满足这些条件,因此相关协议不能直接应用于空间网络.延迟/中断容忍网络(delay/disruptiont01erantnetwork,DTN)是一种通用的面向消息的覆盖层网络体系结构,能够适应空间网络的特点,是实现空间网络互联的有效连接方式.首先阐述了DTN应用于空间网络互联服务(spaceinternetworkingservice,SIS)的体系结构,分析了组成要素和工作模式,包含协议栈构成、消息转发机制、命名与寻址机制等,介绍了支撑空间DTN应用的LTP(1icklidertransmissionprotoc01)协议,并给出了火星探测场景实例;然后针对路由机制、安全机制和服务质量控制3个重点研究方向,阐述了关键技术和进展情况,分析了存在的问题和下一步的研究方向;然后介绍了相关的开发、实践和飞行验证项目;最后分析了在中国开展基于DTN的SIS研究及应用前景.
The increasing demand on space communication stimulates the internetworking and space- ground integration for space communication systems. Space networks are featured in heterogonous subnets, dynamic topology, large transmission delay, and high link errors. TCP/IP protocol suite requires stable connectivity and short transmission delay, which cannot be satisfied in space networks. As a result, existing protocols for the current Internet cannot be directly applied to space networks. Delay/disruption tolerant network (DTN) is a general message-oriented overlay network architecture that can be adapted to space networks. This makes DTN a very promising approach for interconnecting space communication systems. This paper first demonstrates the system architecture which applies DTN in space internetworking service (SIS), and then analyzes the key components and working patterns including protocol stack, message forwarding mechanism, naming and addressing, licklider transmission protocol (LTP), etc. Then we give a real scenario of Mars exploration. By surveying some key technologies and research trends, we analyze some technical problems to be solved and propose some future research directions including routing, security, and QoS control. And then, we introduce related development efforts, practice, and aircraft verification projects. Finally, we analyze the prospects for the research and application of DTN and SIS technologies in China.