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针对由于网络复杂度提高,突发数据在预留时冲突可能性增大,导致OBS网络性能下降的情况,提出OBS网络中的虚拟突发交换技术和相应的实现技术。其汇聚机制是基于服务类别的虚拟汇聚,调度策略对应有两种:非抢占调度策略和抢占调度策略。利用虚拟突发交换技术有利于减少信道碎片,提高链路利用率,提供可靠的QOS保证。用OPNET系统仿真工具进行验证,结果表明:虚拟突发交换与OBS传统交换方式相比有较高网络链路的利用率,较少的控制分组和数据突发的丢包率,增加了整个网络的吞吐量。 相似文献
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Network dimensioning should be progressed for pursuing the ultimate efficiency of network system resources in order to satisfy
target performance. This article studies node dimensioning as a method of resource optimization in optical burst switching
(OBS) networks. OBS is a new switching technology for pursuing bufferless transparent optical networks by sending control
packets prior to data burst in order to provision resources for the burst. However, the basic assumption of a bufferless node
implies burst contention at a core node when more than two bursts attempt to move forward the same output simultaneously.
Thus, burst contention is a critical performance metric and this article takes it into account as a constraint on node dimensioning
and target performance. In this article, we first present node dimensioning issues for OBS networks. Two constraints from
the transport plane and the control plane which affect burst contention are then introduced. The effect of the burst assembly
process on node dimensioning is also presented. From numerical analysis, the optimal number of wavelengths in a link, which
provides the lowest blocking probability, is obtained to suggest a guideline for node dimensioning. 相似文献
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This paper proposes a dynamic burst discarding scheme for deflection routing in optical burst switching networks. In general, deflection routing is effective in lightly loaded situations, whereas it has a contrary effect in congested networks because deflected bursts accelerate network congestion. Thus deflection routing should be employed in lightly loaded networks. Incoming traffic, however, varies in time and location, so that temporal and/or local congestion cannot be avoided. Our proposed scheme resolves this problem in the following way. Each node autonomously detects congestion with local information, and bursts to be deflected are discarded in a probabilistic manner, based on the degree of detected congestion and the numbers of elapsed and remaining hops of those bursts. Simulation experiments show that when congestion happens temporarily, the proposed scheme reduces the burst loss probability, and it utilizes network resources efficiently when local congestion happens. 相似文献
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Techniques for optical packet switching and optical burst switching 总被引:35,自引:0,他引:35
Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth of the Internet. Several different technologies have been developed so far for the transfer of data over WDM. We survey two new technologies which are still in the experimental stage-optical packet switching and optical burst switching-and comment on their suitability for transporting IP traffic 相似文献
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Reinaldo Vallejos Alejandra Zapata-Beghelli Víctor Albornoz Marco Tarifeño 《Photonic Network Communications》2009,17(3):266-276
Existing methods for handling routing and dimensioning in dynamic WDM networks solve the two problems separately. The main drawback of this approach is that a global minimum cost solution cannot be guaranteed. Given that wavelengths are costly resources, determining the minimum network cost is of fundamental importance. We propose an approach which jointly solves the routing and dimensioning problems in optical burst switching (OBS) networks, guaranteeing a target blocking per connection. The method finds the set of routes and the number of wavelengths per network link that minimise the total network cost. To accomplish this, an integer linear programming problem is solved. The proposed method was applied to ring networks, where the optimal solution achieves a reduction in the network cost of 10–40% (for traffic loads <0.4, compared to solving both problems separately). In the case of mesh topologies, to reduce the computational complexity of the method, we applied a variation of it which achieves a local minimum. Even so, a reduction of 5–20% (for traffic loads <0.4) in the network cost was obtained. This ability to lower network cost could make the proposed method the best choice to date for dynamic network operators. 相似文献
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Chi Yuan Zhenrong Zhang Zhengbin Li Yongqi He Anshi Xu 《Photonic Network Communications》2011,21(3):228-237
This article presents a comprehensive study of burst assembly in optical burst switching (OBS) networks. This investigation
aims to provide a unified study of burst assembly algorithms. After analyses of conventional assembly algorithms, we present
an adaptive burst assembly algorithm: data-length time-lag product assembly algorithm. Numerical results show that the proposed
algorithm takes the real-time traffic state into account to adapt burst length and its injected intervals. It obtains a more
acceptable performance. Moreover, we investigated the impact of burst assembly applied at the edge of OBS networks. We analyze
the Hurst parameter of the input traffic to the output traffic that results from the burst assembly. Two formulas are presented
to describe changes of the Hurst parameter. Theoretical results are validated through extensive simulations in time-based,
length-based, and adaptive assembly algorithms, respectively. 相似文献
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Optical Burst Switching (OBS) combines the benefits of Optical Packet Switching and Optical Circuit Switching technologies to provide an efficient, yet cost effective, method for data transmission in an all-optical, bufferless, core network. While most studies on OBS has concentrated on the core OBS network, we contribute new studies for the buffer requirement of an OBS edge node. The buffer usage for OBS systems only arises in the edge nodes since they contain an array of assemblers which combines electronic data with a common destination into an OBS burst stream for transmission in an all-optical bufferless core network. Specifically, we present two analytical results for buffer usage in an OBS edge node: one for Poisson traffic and the other for self-similar traffic input. The results show that the aggregated traffic from many assemblers inherits the characteristics of the source input traffic. This means that the output traffic approaches Poisson if the input traffic is Poisson, and the output traffic remains self-similar if the input is self-similar. These results lead to the following important design issues when dimensioning buffer requirements in an OBS edge node: if the traffic input is Poisson, the M/G/m model is the model to use for obtaining the upper bound on buffer usage in an OBS edge node; and for the case of self-similar traffic, Brichet’s method can be used to provide the upper and lower bound. 相似文献
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QoS performance of optical burst switching in IP-over-WDM networks 总被引:31,自引:0,他引:31
Myungsik Yoo Chunming Qiao Sudhir Dixit 《Selected Areas in Communications, IEEE Journal on》2000,18(10):2062-2071
We address the issue of how to provide basic quality of service (QoS) in optical burst-switched WDM networks with limited fiber delay lines (FDLs). Unlike existing buffer-based QoS schemes, the novel offset-time-based QoS scheme we study in this paper does not mandate any buffer for traffic isolation, but nevertheless can take advantage of FDLs to improve the QoS. This makes the proposed QoS scheme suitable for the next generation optical Internet. The offset times required for class isolation when making wavelength and FDL reservations are quantified, and the upper and lower bounds on the burst loss probability are analyzed. Simulations are also conducted to evaluate the QoS performance in terms of burst loss probability and queuing delay. We show that with limited FDLs, the offset-time-based QoS scheme can be very efficient in supporting basic QoS. 相似文献
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Control plane load stems from burst control packets which need to be transmitted end-to-end over the control channel and further
processed at core nodes of an optical burst switching (OBS) network for reserving resources in advance for an upcoming burst.
Burst assembly algorithms are generally designed without taking into consideration the control plane load they lead to. In
this study, we propose traffic-adaptive burst assembly algorithms that attempt to minimize the average burst assembly delay
subject to burst rate constraints and hence limit the control plane load. The algorithms we propose are simple to implement
and we show using synthetic and real traffic traces that they perform substantially better than the usual timer-based schemes. 相似文献
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A crucial issue in optical burst switching (OBS) networks is burst loss caused by resource contention. As a result, many methods
are currently being proposed to reduce burst loss rate. These methods can be summed up into two categories: burst scheduling
algorithms and contention resolutions. Both categories of methods can reduce burst loss rate to a certain degree. However,
to make OBS to become a viable solution, the burst loss rate needs to be further reduced. Furthermore, almost all methods
ignore the fact that an unfortunately scheduled, locally generated single-hop burst could block a number of future incoming
transit bursts, though the burst just travels to its next downstream node. This phenomenon becomes more evident when links
are heavily loaded in mesh OBS networks. To eliminate contention caused by single-hop traffic completely, this paper proposes
a novel transfer mode called packet calking by differentiating between single-hop traffic from multihop traffic for OBS networks.
An analysis model is developed to evaluate the performance of packet calking. Theoretical results are validated through extensive
simulations in both ring and mesh networks. These results show that packet calking outperforms the transfer mode without packet
calking in terms of burst loss rate and link utilization. 相似文献
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Hoang‐Linh To Suk‐Hwan Lee Won‐Joo Hwang 《International Journal of Communication Systems》2015,28(11):1729-1740
We consider optical delay line buffer as a solution to reduce the number of lost burst in optical burst switching, one of the promising candidates for future networks. Such network takes burst loss as an important performance criteria in the design step. Network performance, however, cannot be captured efficiently using traditional queueing models, because they often ignore the impatience of messages traveling through optical switches which is one of the popular issues in communication networks. In this paper, we develop an analytic model for this system using queueing theory and considering special impatience features. Simulation results show that (i) the developed model with impatience features can decrease burst loss probability ( ? 10%) compared with other approaches, and (ii) applying that model, we demonstrate that shared buffer architecture in optical burst switching network with optical buffer often achieves lower burst loss probability than dedicated buffer way in several different scenarios. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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In this paper, we present the performance analysis of Just-In-Time Optical Burst Switching (JIT-OBS) under realistic web traffic. We demonstrate and explain the impact of Burst Aggregation Time (BAT) on performance under the short-lived TCP flows model. We consider both data and control planes. Our results show that BAT has an impact on TCP performance through packet losses and packet delay in the data plane. The results also show that the network has an optimal point of operation dependence upon BAT. We also incorporate BAT’s impact on the control plane’s congestion. 相似文献
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光突发交换(OBS)网络中数据信道的调度算法是提高OBS网络性能的关键技术之一.文章给出了LAUC、LAUC-VF、BR和LAUC-VF-BS等几种数据信道调度算法的基本原理,通过仿真对这些调度算法进行了性能比较,结果表明LAUC-VF-BS算法能够更有效地降低突发丢失率,提高信道利用率,从而改善网络性能. 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