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弹性分组环(ResilientPacketRing,RPR)是刚被IEEE802.17标准化的主要用于宽带IP光城域网的新型技术,其带宽利用效率和传统环网相比具有较大的优势。论文通过建立弹性分组环基本带宽模型并对其带宽利用率及带宽分配的公平策略进行分析。分析结果表明:RPR带宽利用率在“环形”业务模式下最高,而在星型业务模式下和传统环网相比则无优势;在比较接近实际情况的“网状”业务模式下,基于节点公平的带宽利用率可以到达传统环网的2倍,而基于流的公平策略的带宽利用率可以到达基于节点公平的近2倍,更适合于具有空间重利用能力的RPR。 相似文献
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城域网已成为当前网络建设的热点。城域网建设的链路层候选技术有很多,例如ATM、POS、以太网、帧中继、混和传输等。以上技术各有利弊,但并不能同时满足质量保证、效率、性价比、带宽要求等需求。而新近出现的弹性分组环技术—RPR,集成了IP的智能化、以太网的经济性和光纤环网的高带宽效率和可靠性,被国际上普遍认为是一种很有市场前景的技术。目前IEEE802.17工作组正在对RPR进行标准化工作,已经推出1.0版草案。预计标准正式版本将于2003年3月推出。 相似文献
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近年来,国内外各种针对城域网的新技术层出不穷,弹性分组环技术(RPR,ResilientPacketRing)就是其中的一种,它为人们带来了一种全新的理念。如同SDH一出现就迅速取代PDH一样,以弹性分组环(制订中的IEEE802.17)技术为代表的新型网络解决方案也许将会迅速地取代现有以SDH为基础的数据传输网络。基于RPR技术的城域网多业务平台为大城市城域网带来了一个新的转折点,可能成为未来大城市数据传送平台的基础。一、背景随着互联网的发展,数据通信量正在呈爆炸式的增长。与此相适应,通信网络正进行着种种技术革新。在广域网上,密集波分多路复… 相似文献
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对于RPR(弹性分组数据环)技术,熟识的人并不多,但在运营商建设下一代MAN(城域网)过程中,RPR技术凭借其在分组交换体系中提供包括策略、整形、等级队列等广泛的QoS保障,以及高带宽、低成本等诸多优势,已成为了下一代MAN建设的首选。目前,RPR技术已于9月正式成为了IEEE802.17标准。作为下一代MAN建设的主流技术,RPR技术在N×Gbps以太网物理层上了采用MPLS/MAC体系结构,并增加了性能监控、网络同步和控制分组等保障机制。同时,RPR技术还可以吉比特以太网的成本实现SDH/SONET级的传输可靠性,并且所有流量可在第二层分组中统… 相似文献
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弹性分组环(RPR)是刚被IEEE802.17标准化的主要用于宽带IP光城域网的新型技术,其带宽利用效率和传统环网相比具有较大的优势.弹性分组环从属寄存器插入环(RIR),通过建立基本带宽模型并对寄存器插入环带宽利用及带宽分配的公平策略进行更一般性的研究,分析结果表明:寄存器插入环在"环形"业务模式下带宽利用率最高;而在星型业务模式下和传统环网相比则无优势.在比较接近实际情况的"网状"业务模式下,基于站点公平的吞吐量可以到达传统环网的N/2(N-1)倍(单环),而基于流的公平策略的吞吐量可以到达基于站点公平的近2倍,并且环段带宽利用率到达物理极限的最大值1,是寄存器插入环的最优策略;同时,双环结构比单环结构具有更大的带宽利用效率. 相似文献
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本文简单概述了有关城域网的性质和特征,从城域网的基础结构上叙述了多协议标记交换技术(MPLS)和弹性分组环(RPR)的原理,提出了结合MPLS和RPR技术构建城域网的应用及发展前景。 相似文献
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Hussein Abdel-Jaber Mike Woodward Fadi Thabtah Amer Abu-Ali 《Journal of Network and Computer Applications》2008,31(4):750-770
Due to the rapid development in computer networks, congestion becomes a critical issue. Congestion usually occurs when the connection demands on network resources, i.e. buffer spaces, exceed the available ones. We propose in this paper a new discrete-time queueing network analytical model based on dynamic random early drop (DRED) algorithm to control the congestion in early stages. We apply our analytical model on two-queue nodes queueing network. Furthermore, we compare between the proposed analytical model and three known active queue management (AQM) algorithms, including DRED, random early detection (RED) and adaptive RED, in order to figure out which of them offers better quality of service (QoS). We also experimentally compare the queue nodes of the proposed analytical model and the three AQM methods in terms of different performance measures, including, average queue length, average queueing delay, throughput, packet loss probability, etc., aiming to determine the queue node that offers better performance. 相似文献
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描述了一种新的TCP/IP动态队列管理控制算法,对于传统的随机早期检测法(RED)来说,它的主要目标之一就是稳定路由器队列的长度,然而它实现此目标并不是很成功,主要因为它在平衡队列长度的过程中很强地依赖了动态TCP链接数。而新的动态控制算法则使用了一种简单的控制方法,当路由器缓冲区即将出现拥塞时,它能够根据当前路由器缓冲区负载概率来随机地实施包丢弃。该算法能够很好地稳定路由器缓冲区的队列占用数,同时,在实现过程中并不用评估动态TCP链接数以及分析网络流的状况。所给出的一个实验模型表明,该控制算法是有效可行的。 相似文献
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对共享缓存分组交换机提出了按需分配缓存的具有门限的动态双队列缓存管理策略.具有门限的动态双队列特性,在提高不同优先级业务服务公平性以提供服务质量保证的同时,也提高了缓存的整体有效利用率.据此对该系统建立了M1 M2/M/1/K (K)的排队模型,给出了相应的Q矩阵,利用矩阵几何解方法对模型求解得到了稳态概率分布.最后做了相应的性能分析,定量给出了不同优先级分组的队长分布、丢失概率等的计算公式. 相似文献
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We present a nonlinear flow control scheme based on a buffer management model with physical constraints. It extends previous result of Pitsillides et al. in [6] by improving the queue length regulation for better service of network traffics. Besides a single node system, we also address the decentralized control of many cascaded nodes. The proposed discontinuous controller asymptot-
ically regulates the buffer queue length at the output port of a router/switch to a constant reference value, under unknown time varying interfering traffics and saturation constraints on control input and states. Its continuous approximation achieves practical regulation with an ultimate bound on the regulation error tunable by a design parameter. 相似文献
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The behaviour of the slotted-ALOHA random access satellite channel wherein each user with a finite buffer changes the retransmission probability in accordance with the queue length is studied. The finite buffer of each user is divided into a number of strata and whenever the queue length moves from one stratum to the other, the retransmission probability is changed to reduce the average queueing delay. The analysis carried out in this paper reveals that significant reduction in the delay can be achieved by this technique employing only a few strata. 相似文献
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The resequencing problem is encountered in many practical information systems such as distributed database and communication networks. In these systems customers, such as messages in a computer network, have to be delivered to users in their original order. Therefore, those customers which become out of order due to the randomness of the system are forced to wait in a resequencing buffer so that their delivered order can be guaranteed. The previous work on the resequencing problem mainly concentrated on the delay aspect. From both theoretical and practical viewpoints, however, the queue length characteristics of the resequencing buffer are also significant. We consider the queue length distribution of the resequencing buffer fed by a homogeneous M/M/2 queue. The exact analysis is carried out for the probability mass functions of the queue length in equilibrium and the maximal occupancy which corresponds to the queue length just before the departure instants of customers from the resequencing buffer. 相似文献