共查询到19条相似文献,搜索用时 156 毫秒
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为了降低光突发交换网络中突发包的丢失率、降低网络路径的阻塞率、减小突发包冲突的概率,提出了考虑优先级的突发包碎片可控合并重传算法。当网络中数据通信发生冲突时,该算法能根据优先级进行突发包的分片,核心节点将这一信息反馈给边缘节点,边缘节点根据突发碎片的优先级以一定的概率重传被丢弃的突发包分片;同时,针对由于多次重传导致的突发包碎片过多的问题,该算法还按照突发包碎片的优先级顺序进行碎片重组,大大降低了网络的阻塞率。结果表明,相比以往的冲突解决算法,此算法在网络业务繁忙时的数据丢比特率和网络阻塞率方面的改善作用有比较明显的优势。这一结果对光突发交换网络的网络的性能改善方面是有帮助的。 相似文献
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对采用光纤延迟线(FDL)解决竞争问题的光突发交换网络节点,本文提出了一种新的数学分析模型计算OBS节点的突发包丢失率。模型基于Markovian链及光纤延迟线,推导了状态方程,并通过数值求解各状态的概率来得出交换节点总的突发包丢失率。与此同时用C++语言对节点的交换过程进行了仿真模拟。分析模型与仿真结果的比较表明,两者的一致性相当好。 相似文献
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光突发交换网络中支持业务区分的多路由机制研究 总被引:1,自引:1,他引:0
针对光突发交换(OBS)网络的多路由机制多是考虑一种业务而对多业务区分的多路由机制研究偏少这种现状,提出了一种支持业务区分的多路由(MRSD)机制。在发送各个服务等级的业务之前,首先在没有共享风险链路的多条路由上发送请求包获得各条路由上的多种优先级业务的负载情况,然后根据爱尔兰固定点近似分析法计算各种优先级业务在不同路由上的丢包率,并为每种优先级业务选择一条使本业务丢包率最小的路由;在一个核心节点内,则采用基于额外偏置时间的业务区分方法实现不同优先级业务的区分,将各种业务根据链路状态信息分配到没有共享风险链路的多条路由上去传输,从而在减少突发丢失率(BLP)的同时实现了多种优先级业务在路由上的区分。仿真结果表明,这种多路由机制能够有效降低网络的BLP,实现区分服务。 相似文献
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OBS网络中的主动拥塞控制策略研究及性能分析 总被引:1,自引:0,他引:1
根据光突发交换(Optical Burst Switching--OBS)网络的结构和特点,分析了其核心节点在数据信道调度发生拥塞时拥塞控制策略的缺陷,提出了OBS网络中一种主动拥塞控制策略(ACC),详细讨论了该策略的具体实现过程.通过仿真验证,在OBS网络中采用该算法能减少突发数据包的丢包率,从而达到改善整个OBS网络性能的目的. 相似文献
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Among the various issues lying in optical burst switching (OBS) networks, burstification, i.e., assembling multiple IP packets
into bursts, is an important one. Between the two important aspects related to burst assembly, the burst assembly algorithm
aspect has been extensively studied in the literature. However, as far as we know, there is no research about the burstification
queue management (BQM) aspect, which refers to how many burstification queues (BQ) we should set at each OBS edge node and
how to manage these BQs. Suppose there are G destinations (egress edge nodes) and the OBS network provides S different quality of service (QoS) classes. Traditionally, it is simply regarded that each ingress edge node needs G· S queues to sort incoming packets, one for each possible destination and QoS class. For simplicity, we call this policy the
static dedicate BQM (SDB) policy. The SDB policy, though simple, lacks scalability since we have to add S BQs at each OBS
edge node if an extra OBS edge node is added to the OBS network. To solve this problem, we propose in this paper two BQM policies:
quasi-static BQM (QSB) policy and dynamic BQM (DB) policy. For the QSB policy, we derive the packet loss probability due to
lacking BQs based on a Markov chain, from which we can work out the employed number of BQs for a given packet loss probability.
Based on these results, the scalability of the QSB policy is also studied. With the DB policy, we not only can dynamically
assign BQs for incoming packets, but also can dynamically allocate buffer capacity for each BQ by using a least-mean-square
(LMS)-based linear prediction filter. The performance of the DB policy is investigated by analysis and extensive simulations.
We also compared the performance of the QSB policy and the DB policy. Results from analysis and simulation demonstrate that
the DB policy is the best. 相似文献
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OBS网络中的最小间隙组调度算法 总被引:1,自引:1,他引:0
根据OBS网络的结构和特点,分析了OBS网络核心节点的数据信道调度算法,提出了一种新的数据信道调度算法--最小间隙组调度(SGGS)算法,并详细讨论了该算法的具体实现.该算法将到达核心节点的控制包分组,然后将这一组控制包按数据包到达先后的次序调度数据信道,从而达到合理调度和使用数据信道,最终实现改善整个OBS网络性能的目的. 相似文献
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光突发交换(OBS)是IP over WDM核心网络采用的交换技术。在OBS网络中,送往同一边缘节点的IP分组汇聚成传输和交换的基本单元———数据突发(DB),DB丢弃会导致大量IP分组丢失,显著影响传输层的性能。文中分析OBS网络的参数对传输控制协议(TCP)吞吐量和时延的影响。仿真结果表明,DB丢包率越高,TCP性能越差。在低丢包率情况下,随着DB长度的增加,TCP吞吐量和端到端时延明显增加,高丢包率情况下则不明显;随着汇聚周期的增加,TCP吞吐量逐渐下降,端到端时延逐渐增加。 相似文献
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Neal Charbonneau Deepak Chandran Vinod M. Vokkarane 《Photonic Network Communications》2012,23(1):1-15
Random contentions occur in optical burst-switched (OBS) networks because of one-way signaling and lack of optical buffers.
These contentions can occur at low loads and are not necessarily an indication of congestion. The loss caused by them, however,
causes TCP at the transport layer to reduce its send rate drastically, which is unnecessary and reduces overall performance.
In this paper, we propose forward segment redundancy (FSR), a proactive technique to prevent data loss during random contentions in the optical core. With FSR, redundant TCP
segments are appended to each burst at the edge and redundant burst segmentation is implemented in the core, so that when
a contention occurs, primarily redundant data are dropped. We develop an analytical throughput model for TCP over OBS with
FSR and perform extensive simulations. FSR is found to improve TCP’s performance by an order of magnitude at high loads and
by over two times at lower loads. 相似文献
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光突发交换技术是最具发展潜力的光交换技术之一,而减少突发丢失是其首要问题。传统的静态路由机制不能随着网络负载的变化而更改路由,不能有效应对动态业务。为此,在研究现有动态负载平衡路由机制的基础上,提出了一种基于蚁群探测的路由机制。蚁群根据节点出度链路上的负载变化选择下一跳节点,当转发到目的节点时收集蚁群探测到的所有备选路径,然后根据备选路径中记录的链路负载选择可使丢包最小的路径,通过选择更加合理的路由,达到减少突发丢失率的目的。仿真结果表明,与其他算法相比,所提出的机制表现出比较好的性能,有效降低至少15%突发丢失率。 相似文献