显式拥塞控制协议研究及其稳定性分析

发布时间：2018-04-25 04:04

本文选题：拥塞控制 + XCP协议　；参考：《山东师范大学》2014年硕士论文

【摘要】：计算机技术的飞速发展以及互联网时代的到来，翻开了人们生活方式的新篇章。互联网世界逐渐发展壮大，人们的生活需求也在不断的变化。进入大数据时代，高速数据（如视频流等）传输、特定数据传输服务成为主流，网络环境也因此发生了相应的改变。随着新的网络环境的出现，以及网络世界呈现出的高带宽时延积特性，拥塞控制再次成为人们的重要关注点。而传统的TCP拥塞控制机制在网络环境变化的惊涛骇浪中显示出很多性能上的不足。针对出现的问题，很多中外学者对新环境下的拥塞控制机制进行了大量的研究，一部分学者进行了基于源端拥塞控制算法的研究，在原TCP协议上进行改进研究，取得了一定的成果。而另一部分学者则提出了基于链路的控制方法，在路由器中加入拥塞指示的反馈，将中间通信网络引入到整个拥塞控制机制中，使得数据发送端能够显式地接收当前的网络状况信息。经过大量实验以及理论分析，显式拥塞指示愈来愈体现出其优越性。而其中的XCP协议，以其表现出的高性能而获得学者的青睐，成为新网络环境下进行网络拥塞控制的新趋势。本文对拥塞控制的基本原理进行了讲述，理解传统网络中TCP协议的工作原理，并根据当前网络环境的变化对TCP协议进行了重新评价。随着高带宽时延积网络的出现与发展，TCP协议不能保持系统工作的高效率性，从而无法快速高效地利用网络资源。同时，由于多种应用需求的出现，数据流的公平性要求逐渐升高，而传统TCP协议无法很好地实现对每条数据流的公平分配，这成为TCP协议在新网络环境中发展的瓶颈。除此之外，高带宽时延积网络中的TCP协议无法保证系统的稳定性，使得网络容易陷于抖动之中，很容易导致网络拥塞，甚至崩溃。传统的拥塞控制在新的网络环境中遇到了挑战，而显式拥塞指示的出现让学者们找到了新的研究方向。本文对显式拥塞指示进行了详细讲解，以便于理解XCP协议的发展背景。同时，本文还对系统的稳定性判定定理进行了一定的讲解，以便于对XCP协议系统的稳定性分析。本文详细描述了XCP协议的工作原理，从宏观的角度整体掌握了XCP协议的工作流程。支持XCP协议的数据发送端将带有拥塞信息的数据包发送到网络中，中间通信网络的路由器接收到数据包之后，根据当前的网络情况修改数据包中的拥塞信息，数据包到达目的端，目的端将数据包中最终的拥塞信息以反馈信息的方式发送给发送端，发送端根据反馈信息了解到当前的网络状况，并以此来调整下一周期的发送速率。要完成这一系列的控制工作，需要在数据包中加入存放拥塞信息的拥塞控制头，路由器在估算出当前的网络状况后修改该头结构内的信息。作为XCP协议的关键参与部分，XCP路由器的工作主要分为保证效率性和公平性两部分，分别由效率控制器和公平控制器来完成。本文重点从XCP协议中资源利用的角度进行了分析，通过了解资源计算对资源利用的重要性，分别从参数分析以及带宽补偿两方面进行资源分析方法的讲解。效率控制器中的参数变化对系统的性能产生了影响，通过调整参数的选择方式可以进一步调高算法的资源利用率，并保证整个系统的稳定性以及收敛性。带宽补偿是另一种改善资源计算的方式。通过对控制器的重新调整，在原控制器的基础上进行改进，从而提升整个机制的性能。除此之外，本文提出了一种新的计算网络资源的方法，，除每个控制周期计算的可分配资源外，增加一部分带宽资源，减轻了原算法保守的特性。同时，新算法将带宽重洗考虑在内，更加符合实际情况。实验仿真显示，新算法能够更充分的利用网络资源，并能够保证系统在阈值范围内的稳定性。本文在对XCP协议进行分析、仿真以及改进之后，从控制论的角度对XCP协议进行了理论分析。利用常微分方程描述系统，随后利用李亚普诺夫方法，分别对XCP系统的一般情况以及考虑实际时延的情况进行了分析，验证系统的稳定性条件。
[Abstract]:The rapid development of computer technology and the advent of the Internet era have opened a new chapter of people's life style. The Internet world is growing and growing, and the needs of people are constantly changing. Entering the era of big data, high speed data (such as video stream) transmission, specific data transmission services become the mainstream, and the network environment is also issued. With the emergence of the new network environment and the characteristics of high bandwidth delay product in the network world, congestion control has become an important concern again. The traditional TCP congestion control mechanism shows a lot of inadequacy in the wave of network environment.
In view of the problem, many Chinese and foreign scholars have done a lot of research on the congestion control mechanism under the new environment. Some scholars have done the research on the source based congestion control algorithm, improved the original TCP protocol and achieved some results. While another part of the scholars proposed a link based control method, in the routing. With the feedback of congestion indication, the intermediate communication network is introduced into the whole congestion control mechanism, which enables the data transmitter to receive the current network information explicitly. After a large number of experiments and theoretical analysis, the explicit congestion indication shows its superiority more and more. The XCP protocol shows high performance. It has become the new trend of network congestion control under the new network environment.
The basic principle of congestion control is described in this paper, the working principle of TCP protocol in the traditional network is understood, and the TCP protocol is reevaluated according to the changes of current network environment. With the emergence and development of the high bandwidth delay product network, the TCP protocol can not keep the efficiency and efficiency of the system, so that it can not be used quickly and efficiently. At the same time, due to the emergence of a variety of application requirements, the demand for the fairness of data flow is increasing gradually, and the traditional TCP protocol can not achieve a fair distribution of each data stream. This has become the bottleneck of the development of the TCP protocol in the new network environment. In addition, the TCP protocol in the high bandwidth delay product network can not guarantee the stability of the system. Qualitatively, the network is prone to jitter, which can easily lead to network congestion and even collapse. Traditional congestion control has met challenges in the new network environment, and the emergence of explicit congestion indication has made scholars find new research directions. This paper explains the explicit congestion indication in detail in order to understand the development of XCP protocol. Background, at the same time, we explain the stability theorem of the system in order to analyze the stability of the XCP protocol system.
In this paper, the working principle of XCP protocol is described in detail, and the workflow of the XCP protocol is mastered from a macro point of view. The data packets with congestion information are sent to the network by the data sending end of the XCP protocol. After the router receives the packet, the congestion in the packet is modified according to the current network situation. Information, the packet arrives at the destination, the destination sends the final congestion information in the packet to the sending end in the way of feedback information. The sender understands the current network status according to the feedback information and adjusts the sending rate of the next cycle. Congestion control head of plug information, the router modifies the information in the header structure after estimating the current network condition. As the key part of the XCP protocol, the work of XCP router is divided into two parts: efficiency and fairness, which are completed by efficiency controller and fair controller respectively.
This paper focuses on the analysis of resource utilization in the XCP protocol. Through understanding the importance of resource utilization in resource computing, the paper explains the resource analysis methods from two aspects of parameter analysis and bandwidth compensation. The parameters change in the efficiency controller affects the performance of the system and adjusts the selection of parameters. It can further improve the resource utilization of the algorithm, and ensure the stability and convergence of the whole system. Bandwidth compensation is another way to improve the computing of resources. By the adjustment of the controller, the performance of the whole mechanism is improved on the basis of the original controller. In addition, a new method is proposed. The method of computing network resources, in addition to the allocated resources calculated in each control cycle, increases a part of the bandwidth resources and reduces the conservative characteristics of the original algorithm. At the same time, the new algorithm takes the bandwidth reshuffling into consideration and is more in line with the actual situation. The experimental simulation shows that the new algorithm can make full use of the network resources and can ensure the system in the threshold. Stability within the range of values.
In this paper, after the analysis, simulation and improvement of the XCP protocol, the XCP protocol is theoretically analyzed from the angle of control theory. The system is described by using ordinary differential equations. Then, the general situation of the XCP system and the situation of the actual delay are analyzed by Lyapunov method, and the stability conditions of the system are verified.

【学位授予单位】：山东师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TP393.04

【参考文献】