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针对FAST TCP协议参数选择指导方案存在的缺陷,提出了一种改进FAST TCP模型选择协议参数指导方案。建立了包含窗口更新周期参数和历史窗口值的非线性、时滞FAST TCP网络拥塞控制模型,在平衡点线性化后,采用pade近似式处理其时滞项,应用劳思-郝尔维兹稳定判据获得了确保该模型稳定的相关协议参数和网络参数应满足的条件。根据该稳定性条件,提出了一种根据控制器增益参数、窗口更新周期和网络相关参数选择合适协议参数的指导方案。NS2仿真结果表明,该方案得到更不保守的协议参数设置范围和更广泛的应用范围。 相似文献
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拥塞控制机制是一种分布式算法,本文分析和证明了一种在高速度高延时的TCP协议(FAST TCP)的拥塞控制机制的稳定性.在研究中,使用了一种基于时钟自同步分离时间模型.通过试验证明和理论分析,证明了FAST TCP在单瓶颈链路中拥有的反馈延时可以通过调整参数来达到稳定. 相似文献
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FAST TCP公平性改进研究 总被引:1,自引:0,他引:1
FAST TCP是一种适用于高带宽长延迟的新型TCP拥塞控制协议,它能充分利用网络带宽,但存在比较严重的RTT不公平性.对FAST TCP的RTT不公平性进行了研究,通过仿真试验和数学分析,在原有算法中添加一个公平因子,从而显著改善其公平性和友好性. 相似文献
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网络流量中UDP成分的逐渐增加可能导致网络存在拥塞缓解失效的隐患.通过引入TCP流量与非TCP流量的区分丢包互斥机制,使用Lotka-Volterra竞争模型证明在该机制下TCP与非TCP流量在网络中必然存在平衡点,作者提出基于TCP与非TCP差异型丢包的队列管理机制.该机制依据TCP模型推导出的TCP协议流量的丢包概率,利用当前缓存队列中的TCP和非TCP数据包的状态,对不同的传输层协议产生差异型的动态丢包概率以确保AQM的稳定性和传输层协议间的公平性. 相似文献
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多重稳定性是许多分子生物模型重要的动力学行为,它在分析细胞分裂和生长现象中起到关键性的作用.为了了解细胞内的复杂的调节网络的动力学行为,将其数学模型进行单调分解为若干个单调控制系统的互联.对具有惟一定义的稳定状态响应的单调控制系统,引入了具有保持局部稳定性质的简化系统,根据简化系统的平衡点与原来单调控制系统的平衡点之间存在的一一对应的映射关系,可推知单调控制系统的平衡点的位置及其稳定性.进而通过确定单调控制系统的平衡点的位置及平衡点的稳定性.来确定整个互联单调控制系统的平衡点的位置及平衡点的稳定性.由于简化系统降低了原来生物系统模型的雏数,这为分析复杂生物系统的稳定性提供了一种可行的途径. 相似文献
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随着网络技术的飞速发展和接入性能的不断提高,如今全世界的互联主干网络呈现出一种高速网络的特性。在这种网络特性下,传统网络中的TCP拥塞控制协议已经开始显现出不适应性,发现了FAST TCP协议中"持续拥塞"的形成机制,建立了数学模型来准确的描述"持续拥塞"所导致数据流之间带宽分配不公平的问题,进一步利用优先服务队列的方法解决了FAST TCP在网络中的持续拥塞现象。 相似文献
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Joon-Young Choi 《Automatica》2009,45(10):2462-2466
We consider a class of nonlinear time delay systems created by generalizing the model for FAST TCP, an Internet congestion control algorithm. We achieve a time delay independent sufficient condition for the global asymptotic stability of the class of systems. The sufficient condition is verified by constructing two sequences that represent the lower and upper bound variations of the system trajectory in time, and showing that the two sequences converge to the equilibrium point of the system. The simulation results exemplify that the sufficient condition is valid for global asymptotic stability, and that the sufficient condition is a close approximation to the unknown necessary and sufficient condition for global asymptotic stability. 相似文献
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FAST TCP协议研究及性能分析 总被引:2,自引:0,他引:2
FASTTCP是一种面向高速长延迟网络的新型TCP拥塞控制协议,它从根本上改变了传统TCP的拥塞控制机制。论文对FASTTCP进行了详细研究,讨论了其设计动机、体系结构和算法实现,在Linux2.4.22内核中嵌入了FASTTCP协议。在千兆以太网内设计了一系列实验,使用iperf网络测量工具,测试了传统TCP与FASTTCP的性能。实验验证了即使在延迟较小的局域网内FASTTCP较传统RenoTCP也具有一定的性能优势。 相似文献
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Wenjun Xu Author Vitae Zude Zhou Author Vitae Author Vitae C. Ji Author Vitae Author Vitae Quan Liu Author Vitae 《Journal of Systems and Software》2010,83(12):2642-2652
Currently there is no control for the real-time traffic of multimedia applications using UDP (User Datagram Protocol) in high-speed networks. Therefore, although a number of high-speed TCP (Transmission Control Protocol) protocols have been developed for gigabit-speed (or faster) links, the real-time traffic could also congest the network and result in unfairness and throughput degradation of TCP traffic. In this paper, a new unreliable transport protocol, FAST DCCP, is presented for the real-time traffic in high-speed networks. FAST DCCP is based on the DCCP protocol and adopts the FAST scheme to realize congestion control. Some modifications have been made to the mechanisms inherited from DCCP so as to let the proposed protocol can efficiently operate under a large size window. In addition, an enhanced protocol, EEFAST DCCP, using the measurements of one-way delay to dynamically adjust the window size is also proposed to improve the throughput of FAST DCCP with the effect of reverse traffic. Simulation results show that FAST DCCP not only can satisfy the requirements of real-time data delivery, but also perform well in bandwidth utilization and fairness in high-speed networks. Meanwhile, EEFAST DCCP is able to effectively conquer the throughput degradation caused by the reverse traffic. 相似文献
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Joon-Young Choi Kyungmo Koo Jong-Wook Kim Jin S. Lee 《International Journal of Control, Automation and Systems》2009,7(5):809-816
We propose a continuous-time model to describe a single-link single-source network with the FAST TCP source. The proposed
model explicitly includes both the queuing delay dynamics for the link dynamics and the time-varying network feedback delay.
Based on the proposed model, we establish a sufficient condition for the global asymptotic stability of the FAST TCP network.
We prove the sufficient condition by constructing two sequences that represent the variations of the lower and upper bound
of the source’s congestion window with respect to time, and by showing that the two sequences converge to the equilibrium
point of the congestion window. The simulation results illustrate the validity of the sufficient condition for the global
asymptotic stability. 相似文献
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Proposals to improve the performance of TCP in high speed networks have been recently put forward. Examples of such proposals include High Speed TCP, Scalable TCP, and FAST. In contrast to the additive increase multiplicative decrease algorithm used in the standard TCP, Scalable TCP uses a multiplicative increase multiplicative decrease (MIMD) algorithm for the window size evolution. In this paper, we present a mathematical analysis of the MIMD congestion control algorithm in the presence of random losses. Random losses are typical to wireless networks but can also be used to model losses in wireline networks with a high bandwidth-delay product. Our approach is based on showing that the logarithm of the window size evolution has the same behaviour as the workload process in a standard G/G/1 queue. The Laplace–Stieltjes transform of the equivalent queue is then shown to directly provide the throughput of the congestion control algorithm and the higher moments of the window size. Using ns-2 simulations, we validate our findings using Scalable TCP. 相似文献
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详细研究了VFAST TCP协议,讨论了其设计动机和算法实现.重点论述了往返时延的估算问题.在NS仿真环境下对VFAST和FAST的拥塞控制算法进行了仿真,并针对仿真结果分析总结了VFAST TCP性能的优越性. 相似文献