【作者】 田栋；

【导师】 张丽；

【作者基本信息】 北京工业大学 ， 软件工程（专业学位）， 2018， 硕士

【摘要】 自从步入21世纪以来,计算机和互联网技术飞速发展,以惊人的速度深入到了我们生活的每一个角落。但是这样快速的发展并不是全面的,随着互联网高层技术的飞速发展,上世纪所规定的网络协议和架构已经远远无法支撑如雨后春笋般的新兴技术了。所以更新新的网络协议和架构迫在眉睫。2010年,美国国家科学基金会提出了命名数据网络(即NDN网络),其前沿的思想和创新的机制瞬间引起了全世界的相关研究者们瞩目。然而由于IP网络基础的限制,NDN网络一时间无法形成大规模的部署。本文将参考NDN网络的这些机制与特性,结合当下最为流行的互联网直播这种信息载体,设计并实现一个基于NDN机制的互联网直播系统,以满足用户对网络直播的需求。本课题的主要研究方向,就是将NDN机制运用于网络直播,传统的TCP/IP体系结构以IP地址为核心,从而进行地址转发,要求必须解析到对应的宿主主机地址才能完成通讯。而NDN基于数据名称的传输分组,将解析与路由过程合并,或者将该过程剔除,在减少冗余数据的同时,还能使节点路由器缓存更多的数据,便于提高传输效率。所以,可以说NDN是为网络流媒体量身定做的。所以,一方面,NDN作为未来网络架构的潜在发展方向,必然会出现基于NDN网络的互联网直播系统;另一方面,将NDN机制运用于互联网直播,可以说是对症下药,NDN本生的特点正好可以用于解决互联网直播目前面临的问题,也可以满足未来急速增长的互联网直播需求,可以说是一举两得。本课题的目标是通过结合现有方法,设计一个基于NDN机制的网络直播系统。本系统的结构分为流媒体采集层、基于NDN机制的数据分发层和流媒体播放层三大模块。流媒体采集层负责通过用户的内置摄像头等视频采集设备,将用户的直播画面进行采集和编码,并将不同的格式转换成能够直播的视频格式;流媒体播放层测试通过获取接收到的帧数据,对其进行拼接,然后播放;数据分发层的设计是本文研究的核心,通过借鉴NDN网络机制来完成流媒体直播数据在采集完成后以不同的规则通知目录管理服务器和预处理服务器,规定数据在路由节点应该遵循怎样的原则进行传递,以及数据包本身格式和名称规则的设计。同时,本文提出了一种新的TD(Time-Delet)缓存替换策略,通过该策略,优化在NDN网络机制中的路由器的缓存规则,使得缓存节点可以更为有效的缓存更有用的数据,优化网络用户的使用体验。最后,本文在ndnSIM上实现了TD缓存替换策略并对本系统进行了基本的实现。本文通过将TD缓存替换策略与目前NDN网络中现有的原生生命周期缓存替换策略和LRU缓存替换策略进行比较,根据对比试验产生的数据,证明了TD缓存替换策略能够有效的降低网络延迟,提高缓存命中率,同时也发现了该策略的一些不足和有待改进的地方。更多还原

【Abstract】 Since the beginning of the 21 st century,computer and Internet technology have developed rapidly,reaching every corner of our lives at an astonishing speed.However,such rapid development is not comprehensive.With the rapid development of high-level Internet technologies,the network protocols and architectures stipulated in the last century have been far from supporting emerging technologies that have sprung up.So updating new network protocols and architectures is imminent.In 2010,the National Science Foundation proposed the Named Data Network(NDN),and its cutting-edge ideas and innovative mechanisms have caught the attention of researchers around the world.However,due to the limitations of the IP network,the NDN network cannot form a large-scale deployment for a time.This article will refer to these mechanisms and characteristics of the NDN network,combined with the current most popular Internet live information carrier,design and implement an NDN-based Internet live broadcast system to meet the user’s demand for webcasting.The main research direction of this topic is to apply the NDN mechanism to the live webcast.The traditional TCP/IP architecture uses the IP address as the core to carry out address forwarding.It requires that the corresponding host address must be resolved to complete the communication.The NDN based on the data name of the transmission packet,the analysis and routing process merged,or remove the process,while reducing redundant data,but also allows the node router to cache more data,and facilitate the increase of transmission efficiency.Therefore,it can be said that NDN is tailor-made for network streaming media.Therefore,on the one hand,as a potential development direction of the future network architecture,NDN will inevitably appear on the Internet live broadcast system based on the NDN network;on the other hand,applying the NDN mechanism to the Internet live broadcast can be said to be the right remedy,and the characteristics of the NDN native can just be The problems that are currently facing the Internet broadcast can also meet the needs of the rapidly growing Internet broadcast in the future.It can be said to serve two purposes.The goal of this project is to design a network live broadcast system based on the NDN mechanism by combining existing methods.The architecture of the system is divided into three parts: a streaming media acquisition layer,a data distribution layer based on an NDN mechanism,and a streaming media playback layer.The streaming media collection layer is responsible for capturing and encoding the user’s live video through video capture devices such as the user’s built-in camera,and converts the different formats into a live video format.The streaming media layer buffers the video stream.Processing,spelling frames,codec,and finally restore playback;the design of the data distribution layer is the focus of this study,using NDNbased mechanisms to achieve streaming media live data after the collection is completed to inform the directory management server and pre-processing server with different rules.The data is passed on the principle that the routing node should follow,as well as the design of the format and name rules of the data packet itself.At the same time,this paper proposes a new TD(Time-Delet)cache replacement strategy.Through this strategy,the cache rules of routers in the NDN network mechanism are optimized so that the cache nodes can cache more useful data more efficiently.Web user experience.Finally,this paper implements TD cache replacement strategy on ndnSIM simulation platform and implements the system simply.This paper compares the TD cache replacement strategy with the existing native lifecycle cache replacement strategy and LRU cache replacement strategy in the current NDN network.According to the data generated by the comparison experiment,it is proved that the TD cache replacement strategy can effectively reduce the network delay and improve Cache hit rate,but also found some deficiencies in the strategy and areas for improvement.更多还原