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MBLUE(Modified BLUE)是一种面向数据流的活动队列管理算法.它不是使用平均队列长度指示缓冲区拥塞状态,而是使用数据报丢弃的频率和队列空闲程度来管理网络拥塞.探测瓶颈连接早期的拥塞信息,通过数据报的丢弃和标记避免拥塞.它只维护一个先进先出队列,以较少的数据流状态信息,在不同流之间公平的分配网络带宽.能够适应瞬时的猝发流,能合理控制非TCP数据流,又能够保持较短的平均队列长度,从而控制、减轻网络拥塞.通过TCP/IP网络的模拟,证实算法在公平的分配网络带宽和降低数据报的丢失率上具有较好的鲁棒性. 相似文献
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讨论了网络公平服务中的公平拥塞控制方法,针对解决这一问题的彩虹公平队列(Rainbow Fair Queuing,RFQ)法,提出了可以改进QoS的对网络速率编码的速率空间方法和一种新的网络层次丢弃算法。 相似文献
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传感器网络拥塞避免与控制的模糊AQM算法 总被引:2,自引:0,他引:2
传感器网络节点通信能力有限,当数据到达速率持续超过节点转发能力时网络会发生拥塞;传感器网络是任务型网络,对不同优先级的信息具有不同的服务质量要求.针对传感器网络信息传输的上述特性,提出了一种新的拥塞避免与控制算法FAQM(Fuzzy Active Queue Management).该算法在综合考虑数据包的随机指数标记概率和优先级权值的基础上,建立了模糊逻辑推理系统,并以数据包丢弃因子作为参量来实现数据流的智能调控.NS2仿真实验结果表明:FAQM算法能减少高优先级数据包的丢弃率和节点间链路的时延,稳定节点队列长度,在有效避免与控制拥塞网络的同时提升网络整体QoS(Quality of Service)性能. 相似文献
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主动队列管理 (ActiveQueueManagement,AQM)技术作为Internet拥塞控制的一种有效方法 ,对于提高In ternet的服务质量具有十分重要的作用 .本文根据TCP拥塞控制算法基于数据包丢失的窗口变化机制 ,设计了一种基于模糊逻辑的主动队列管理算法 .该算法依据路由器中队列长度的变化情况 ,根据一定的模糊自校正原则来调整数据包的丢弃概率 ,从而使路由器中的队列长度稳定在参考值附近 .仿真结果表明该算法不但十分有效 ,而且对不同的网络状况具有很好的适应能力 . 相似文献
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主动队列管理通过网络中间节点有控制的分组丢弃实现了较低的排队延时和较高的有效吞吐量,是TCP端到端拥塞控制近来研究的一个技术热点.已有的大多数算法在判定分组丢弃时大都沿袭了RED的概率丢弃机制,具有一定计算复杂度的随机数生成过程不利于路由器性能的优化.在本文中,我们首先定义了拥塞指数这一新的测度变量来量化描述网络的拥塞状态.接着,利用模糊逻辑设计了一种新的智能分组丢弃机制,离线的合成推理使得分组丢弃的判定仅需要简单的查表操作和比较运算即可完成,为优化路由器的性能提供了便利.数字仿真的结果表明:智能分组丢弃机制的性能优于经典的RED算法,控制队列的能力强,鲁棒性好,稳定工作域大,能很好地抵抗突发性和非弹性业务的干扰,适合工作在瞬息万变的动态网络环境中. 相似文献
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一种基于模糊逻辑的主动队伍管理算法 总被引:2,自引:0,他引:2
主动队列管理(AciiveQueue Management,AQM)技术作为Internet拥塞控制的一种有效方法,对于提高Internet的服务质量具有十分重要的作用,本文根据TCP拥塞控制算法基于数据包丢失的窗口变化机制,设计了一种基于模糊逻辑的主动队伍管理算法,该算法依据路由器中队列长度的变化情况,根据一定的模糊自校正原则来调整数据包的丢弃概率,从而使路由器中的队列长度稳定在参考值附近,仿真结果表明该算法不但十分有效,而且对不同的网络状况具有很好的适应能力。 相似文献
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One of the challenges in the design of switches/routers is the efficient and fair use of the shared bottleneck bandwidth among different Internet flows. In particular, various active queue management (AQM) schemes have been developed to regulate transmission control protocol traffic in response to router congestion. In addition, in order to provide fair bandwidth sharing, these AQM must protect the well-behaved flows from the misbehaving flows. However, most of the existing AQM schemes cannot provide accurate fair bandwidth sharing while being scalable. The key to the scalability and fairness of the AQM schemes is the accurate estimation of certain network resources without keeping too much state information. We propose a novel technique to estimate two network resource parameters: the number of flows in the buffer and the data source rate of a flow by using a capture-recapture (CR) model. The CR model depends on simply the random capturing/recapturing of the incoming packets, and as a result, it provides a good approximation tool with low time/space complexity. These network resource parameters are then used to provide fair bandwidth sharing among the Internet flows. Our experiments and analysis will demonstrate that this new technique outperforms the existing mechanisms and closely approximates the "ideal" case, where full state information is needed. 相似文献
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In this work we examine how quality of service (QoS) can be achieved in a real network by allowing packets to coordinate using fiat money in a market economy for router queue positions. In this context we implement and evaluate the PacketEconomy mechanism in the discrete‐event simulator OMNET++, using the standard INET library for simulating Internet Protocol version 6 networks and evaluate throughput, end‐to‐end delay, and packet drop rates. Additionally, we examine whether the flows have a game‐theoretic incentive to participate in the market economy, while covering both Transmission Control Protocol– and User Datagram Protocol–based flows in multiple different cases. The mechanism achieves QoS by allowing packets with different QoS requirements waiting to be served in router queues to mutually trade positions by exchanging money. Notably, each flow can independently and selfishly define the ask and bid prices of its packets. In this manner, packets can coordinate to be able to self‐regulate their packet‐specific access to shared network resources. The results are promising and show that the innovative PacketEconomy mechanism provides robust, effective, and fine‐grained QoS while maintaining end‐user control for both rate‐ and window‐based flows. 相似文献
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We present a method for creating differential QoS where control is in the hands of the end system or user, and the network distributes congestion feedback information to users via packet marking at resources. Current proposals for creating differential QoS in the Internet often rely on classifying packets into a number of classes with routers treating different classes appropriately. The router plays a critical role in guaranteeing performance. In contrast, there is a growing body of work that seeks to place more of the control in the hands of the end system or user, with simple functionality in the router. This is the approach outlined in this tutorial article: using insights from economics and control theory we show how cooperation between end systems and the network can be encouraged using a simple packet marking scheme. The network distributes congestion feedback information to users via packet marking at resources, and users react accordingly to obtain differential QoS 相似文献
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James Aweya Michel Ouellette Delfin Y. Montuno 《International Journal of Communication Systems》2002,15(4):287-307
It is now widely accepted that a RED [2] controlled queue certainly performs better than a drop‐tail queue. But an inherent weakness of RED is that its equilibrium queue length cannot be maintained at a preset value independent of the number of TCP active connections. In addition, RED's optimal parameter setting is largely correlated with the number of connections, the round‐trip time, the buffer space, etc. In light of these observations, we propose DRED, a novel algorithm which uses the basic ideas of feedback control to randomly discard packets with a load‐dependent probability when a buffer in a router gets congested. Over a wide range of load levels, DRED is able to stabilize a router queue occupancy at a level independent of the number of active TCP connections. The benefits of stabilized queues in a network are high resources utilization, predictable maximum delays, more certain buffer provisioning, and traffic‐load‐independent network performance in terms of traffic intensity and number of connections. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Communication networks are time varying and, hence, fair sharing of network resources among the users in such a dynamic environment is a challenging task. In this context, a time‐varying network model is designed, and the shortest user's route is found. In the designed network model, an end‐to‐end window‐based congestion control scheme is developed with the help of internal nodes or router, and the end user can get implicit feedback (throughput). This scheme is considered as fair if the allocation of resources among users minimizes overall congestion or backlog in the networks. Window update approach is based on a multi‐class fluid model and is updated dynamically by considering delays (communication, propagation, and queuing) and the backlog of packets in the user's routes. Convergence and stability of the window size are obtained using a Lyapunov function. A comparative study with other window‐based methods is also provided. 相似文献
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This paper presents a scheme to perform QoS management and assure network security by using the trusted-router based on the Trust Management System.In this trusted-router,every IP packet is forwarded and queued by its trust value,which is the quantification of the network's expectation for this packet's and its owner's behavior in the network.We outline the algorithms to calculate the trust value of the trusted-router and the IP packet.We also introduce the trust-based QoS management algorithm and the deplo... 相似文献
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IP QoS要求是综合宽带网发展的重要瓶颈,而现有IP QoS体系不能很好地满足用户需求,因此,本研究将对IP QoS体系做一个新探索.依托当前网络环境、着眼于下一代网络发展,研究一种网边缘控制的自组织IP QoS体系结构及其算法.本体系中采用探测分组、染色分组和信息分组三类分组,并通过智能控制系统来控制三类分组的比例关系,有效地提供用户所需求的QoS. 本体系将克服现有机制的流状态保持,并通过用户的自组织行为来加强网络的自适应性与可扩展性,更好适应网络发展与应用需求. 相似文献
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分段路由(segment routing,SR)是近几年IETF提出的一种路由机制,其目的是使IP/MPLS网络面向服务并且更高效.SR减少现有MPLS网络控制平面复杂的协议(LDP/RSVP-TE),并实现流量工程等机制.与基于RSVP的显式路径中隧道中间节点维护报文流的状态不同,基于SR的显式路径只在入口边界路由器中维护报文流的状态,从而提高了网络的可扩展性,因此SR对于下一代互联网具有重要的研究意义.对SR的实现机制进行了研究,利用软件路由平台Click,对基于PCE架构的SR控制平面子系统和基于MPLS的SR数据平面子系统的各个模块进行实现,并在实际中进行部署,以验证SR软件路由器的可行性. 相似文献
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Suter B. Lakshman T.V. Stiliadis D. Choudhury A.K. 《Selected Areas in Communications, IEEE Journal on》1999,17(6):1159-1169
There has been much interest in using active queue management in routers in order to protect users from connections that are not very responsive to congestion notification. An Internet draft recommends schemes based on random early detection for achieving these goals, to the extent that it is possible, in a system without “per-flow” state. However, a “stateless” system with first-in/first-out (FIFO) queueing is very much handicapped in the degree to which flow isolation and fairness can be achieved. Starting with the observation that a “stateless” system is but one extreme in a spectrum of design choices and that per-flow queueing for a large number of flows is possible, we present active queue management mechanisms that are tailored to provide a high degree of isolation and fairness for TCP connections in a gigabit IP router using per-flow queueing. We show that IP flow state in a router can be bounded if the scheduling discipline used has finite memory, and we investigate the performance implications of different buffer management strategies in such a system. We show that merely using per-flow scheduling is not sufficient to achieve effective isolation and fairness, and it must be combined with appropriate buffer management strategies 相似文献
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An attractive target for a computer system attacker is the router. An attacker in control of a router can disrupt communication by dropping or misrouting packets passing through the router. We present a protocol called WATCHERS which detects and reacts to routers that drop or misroute packets. WATCHERS is based on the principle of conservation of flow in a network: all data bytes sent into a node, and not destined for that node, are expected to exit the node. WATCHERS tracks this flow, and detects routers that violate the conservation principle. We show that WATCHERS has several advantages over existing network monitoring techniques. We discuss WATCHERS response to several different types of bad router behavior. We demonstrate that in ideal conditions WATCHERS makes no false positive diagnoses, and we describe how WATCHERS can be tuned to perform nearly as well in realistic conditions. Also, we argue that WATCHERS impact on router performance and WATCHERS memory requirements are reasonable for many environments 相似文献