共查询到19条相似文献,搜索用时 109 毫秒
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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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信道调度算法是提高光突发交换(OBS)网络性能的关键技术之一.结合ODBR重调度算法和FDL的延迟作用,提出来一种Improved-OBDR算法.仿真结果表明改进算法在保证高优先级低丢包率的同时,保证低优先级尽可能低的丢包率,提高了资源利用率. 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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光突发交换(Optical Burst Switching,OBS)网络是下一代IP over WDM全光网络的发展趋势.文章主要研究并分析了OBS网络中配备有光缓存的核心路由器性能,给出了突发数据分组阻塞率、输出端口占用率、排队时延等性能参数.所得结果对0BS网络理论研究进行了一定的补充. 相似文献
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在无缓存的全光OBS网络中由于相互竞争而被丢弃的数据突发是造成其高丢包率的主要原因,而分组调度策略可以从整体上改善OBS网络的这种缺点。本文建立了一种改进的分组调度映射模型,并提出了一种基于完全图的分组调度算法,该算法相对简单且容易实现,能够较好地解决OBS网络中由于数据突发的无序竞争所致的丢包问题,从而进一步提高网络的服务质量及其信道利用率。 相似文献
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Optical Burst Switching (OBS) has been proposed as a promising switching technology for the next generation of optical transport networks. In this paper, we address the issue of how to provide proportional differentiated services in OBS networks. Firstly, a Dynamic Wavelength Selection (DWS) scheme is introduced to provide proportional differentiated services in bufferless OBS networks by dynamically assigning more and longer periods of wavelengths to high priority classes. This scheme can also utilize wavelengths efficiently because the wavelengths are shared among different classes. Next, a Delayed Burst Assignment (DBA) scheme is introduced, by which bursts of the high priority class are given a higher probability for reserving wavelengths by scheduling the bursts of the low priority class with a delay to provide quality of service (QoS) in OBS networks. The integration of these two schemes provides proportional differentiated services and improves the burst loss performance by giving the burst head packet (BHP) two opportunities of scheduling its data burst (DB). 相似文献
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Optical burst switching (OBS) is one of the most important switching technologies for future optical wavelength division multiplexing (WDM) networks and the Internet. The model of differentiated services has been proposed to support quality of service (QoS) in the IP‐based Internet. It is also very important to have differentiated service support in OBS networks. When the burst scheduling in an OBS network is set up appropriately, network can support differentiated services. In this paper, we proposed a new burst scheduling scheme, called differentiated scheduling with identical priority offset time (DSIPO). In DSIPO, the same priority offset time is used for all the bursts destined to the same edge node regardless of their priorities. Differentiated services in terms of burst loss probability are achieved by processing the control packets of higher priority class bursts, thus reserving resources for their data bursts, more promptly upon their arrival than those of lower priority class bursts. Each intermediate (core) node can adjust the burst loss probabilities of various burst classes by choosing its own differentiated processing delay value for each priority class or its own differentiated processing delay difference value between any pair of adjacent priority classes. We model and analyse DSIPO in terms of the burst loss probability for each priority class with simulation validation. The performance of DISPO is evaluated by simulation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Hybrid offset‐time and burst assembly algorithm (H‐OTBA) for delay sensitive applications over optical burst switching networks 下载免费PDF全文
Abdulsalam A. Yayah Yahaya Coulibaly Abdul Samad Ismail George Rouskas 《International Journal of Communication Systems》2016,29(2):251-261
Optical burst switching (OBS) is the most favourable switching paradigm for future all‐optical networks. Burst assembly is the first process in OBS and it consists of aggregating clients packets into bursts. Assembled bursts wait for an offset time before being transmitted to their intended destinations. Offset time is used to allow burst control packet reserve required resources prior to burst arrival. Burst assembly process and offset‐time create extra delay in OBS networks. To make OBS suitable for real time applications, this extra latency needs to be controlled. This paper proposes and evaluates a novel offset time and burst assembly scheme to address this issue. Constant bit rate (CBR) traffic that has stringent end‐to‐end delay QoS requirements is used in this study. The proposed scheme is called hybrid offset‐time and burst assembly algorithm (H‐OTBA). The objective of the paper is achieved by controlling maximum burst transfer delay parameters of CBR. The proposed scheme was evaluated via network simulation. Simulation results demonstrate that, H‐OTBA has effectively reduced end‐to‐end delay for CBR traffic compared with current solutions. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Optical burst switching (OBS) is a promising technology for bridging the gap between optical wavelength switching and optical
packet switching. Optical signal transmission quality is subject to various types of physical impairment introduced by optical
fibers, switching elements, or other network components. The signal degradation due to physical impairment may be significant
enough such that the bit-error rate of received signals is unacceptably high at the destination, rendering the signal to not
usable. In this article, based on earlier study, we study the burst-scheduling problem in OBS networks using two control packets
for each data burst, taking into account physical impairment effects. We propose a burst-scheduling algorithm that accommodates
incoming bursts by primary path routing, deflection routing, and burst scheduling. We design an admission control mechanism
to use network resources efficiently. At an OBS node, the proposed algorithm schedules bursts for transmission by searching
for available resources as well as verifying signal quality. Our simulation results demonstrate that the proposed algorithm
is effective in terms of reducing the burst-blocking probability. 相似文献
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光突发交换中的突发包组装技术研究 总被引:3,自引:0,他引:3
光突发交换是近几年出现的一种很有前途的光交换技术,比电路交换灵活,带宽利用率高,又比光分组交换易于实现,突发包的组装是光突发交换的关键技术,在很大程度上影响到光突发交换网络的性能。文中介绍了光突发包的格式,描述了交换网络中突发包组装所需的层次结构和功能结构,并给出了一种典型的生成算法。最后,对选择突发包组装时间应考虑的各种因素进行了系统的分析。 相似文献