基于SDN的P2P直播系统的研究

发布时间：2019-03-04 11:12

【摘要】：网络技术的飞速发展使得业务种类日渐丰富多彩,业务数量呈现爆发式增长。在众多的业务种类中,流媒体业务以其直观、生动、实时、方便的特点吸引了广泛用户。使用互联网请求流媒体视频的用户数和业务量日益增长,尤其是直播流媒体视频传输的需求增加显著,如何利用因特网高效传输流媒体直播视频成为一个重要问题。与传统的服务器-客户端模式相比,对等网络(Peer-to-Peer, P2P)应用被看作是更具可扩展性和成本效益的方案。由于每个加入到P2P的用户即作为客户端又作为服务器,这使得源服务器的压力大大降低。一般来说,P2P系统的服务能力会随用户数量的增加而提升,越多用户加入到P2P系统,可用的上行带宽就越多。虽然当前的P2P视频直播系统展现出了高效地将视频内容直播给众多互联网用户的潜力,但是已成功部署的P2P直播系统存在严重的问题：首先,当前的P2P应用缺少物理位置感知：当前的P2P直播系统缺少Peer节点物理位置感知能力,因此构建P2P逻辑网络时往往采取随机选择邻居关系的策略,使得P2P系统中交换直播数据块的邻居经常是跨运营商、跨区域的。直播数据块传输经常要经历多跳路由,对网络传输带宽、交换设备计算资源造成极大浪费。其次,当前的P2P直播系统缺少动态调度功能：由于没有主动测量Peer节点交换数据使用的路径,没有对拥塞路径做出及时调整,当前P2P直播系统不能达到数据传输路径最优。P2P直播系统与其他P2P业务的不同之处是,直播系统对数据传输延迟的敏感度更高。因此,及时探测出现网络拥塞的路径,并将直播数据包的传输路径转移到负载较轻的路径上,能够有效降低直播数据传输延迟,极大提升P2P直播系统的性能。本文提出在软件定义网络(Software-Defined Network,SDN)中部署P2P直播系统的方案——OpenP2P,可以有效解决当前P2P直播系统中存在的问题。在OpenP2P系统中,SDN控制器为P2P直播系统的Tracker服务器提供物理网络拓扑视图,使Tracker服务器为加入P2P网络的Peer节点选择物理位置最近、传输直播数据消耗带宽费用最少的节点作为邻居。另外,通过设计SDN控制器模块使其能够探测出网络链路的传输延迟性能,对出现拥塞的传输路径进行动态调整,使用较轻负载的路径代替拥塞路径传输直播数据片段,实现数据传输最优化。实验结果表明,OpenP2P与传统P2P直播系统相比,在带宽费用消耗与直播数据块传输延迟方面,性能明显得到了提升。
[Abstract]:With the rapid development of network technology, the types of business are becoming more and more colorful, and the number of services is increasing rapidly. Streaming media service attracts a wide range of users because of its intuitionistic, vivid, real-time and convenient characteristics. The number of users and traffic requesting streaming media video using Internet is increasing day by day, especially the demand of live streaming video transmission is increasing significantly. How to use the Internet to transmit live streaming video efficiently becomes an important problem. Compared with the traditional server-client model, Peer-to-Peer, P2P (Peer-to-Peer) application is regarded as a more scalable and cost-effective solution. Because each user joins P2P as both client and server, the pressure of source server is reduced greatly. Generally speaking, the service capability of P2P system will be improved with the increase of the number of users. The more users join P2P system, the more available uplink bandwidth will be. Although the current P2P video broadcast system has demonstrated the potential to broadcast video content efficiently to many Internet users, the successfully deployed P2P live broadcast system has serious problems: first, The current P2P applications lack physical location awareness: the current P2P live broadcast system lacks the physical location awareness ability of Peer nodes, so the strategy of randomly selecting neighbor relationships is often adopted when constructing P2P logical networks. The neighbors who exchange live data blocks in P2P system are often cross-operator and cross-region. Live data block transmission often goes through multi-hop routing, resulting in a great waste of network transmission bandwidth and switching equipment computing resources. Secondly, the current P2P live broadcast system lacks the dynamic scheduling function: because there is no active measurement of the path used by Peer nodes to exchange data, there is no timely adjustment to the congestion path. The difference between P2P live broadcast system and other P2P services is that the live broadcast system is more sensitive to the delay of data transmission. Therefore, detecting the path of network congestion in time and transferring the transmission path of live broadcast data packet to the path with less load can effectively reduce the transmission delay of live broadcast data and greatly improve the performance of P2P live broadcast system. In this paper, a scheme of deploying P2P live broadcast system in software defined network (Software-Defined Network,SDN), OpenP2P, is proposed, which can effectively solve the problems existing in current P2P live broadcast system. In the OpenP2P system, the SDN controller provides a physical topology view for the Tracker server of the P2P live broadcast system, which enables the Tracker server to select the nearest physical location for the Peer node joining the P2P network. The nodes that consume the least bandwidth to transmit live data are neighbors. In addition, the SDN controller module is designed so that it can detect the transmission delay performance of the network link, dynamically adjust the transmission path with congestion, and use the path with lighter load instead of the congestion path to transmit live data fragments. The optimization of data transmission is realized. The experimental results show that compared with the traditional P2P live broadcast system, the performance of OpenP2P has been improved obviously in terms of bandwidth cost consumption and transmission delay of live broadcast data blocks.
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN919.8

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