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1.
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
2.
José Alberto Hernández Javier Aracil Víctor López Jorge López de Vergara 《Photonic Network Communications》2007,14(1):49-62
In Optical Burst Switching (OBS), packets travel through the network core as part of longer-size optical bursts, which do
not suffer electronic conversion until they reach an eggress point. Typically, such optical bursts comprise tens or hundreds
of packets, which are assembled/deassembled at border nodes. During the burst-formation process, each arriving packet must
wait until the final burst is complete, which clearly adds an extra delay on each packet in the burst, especially on those
arriving earlier. However, such burst-assembly delay may be excessive for the appropriate performance of certain applications,
mainly real-time interactive ones. This work’s findings are twofold: first, it characterises the burst-assembly delay distribution
of each packet in a burst arisen by the main assembly algorithms found in the literature; and, second, it introduces a new
burst-assembly strategy that takes into account the particular delay constrains of packets in the formation of optical bursts,
along with a detailed study of its properties.
This work has been funded by the “Ministerio de Educación y Ciencia” of Spain under grant TEC2006-03246. 相似文献
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4.
Xiang Yu Jikai Li Xiaojun Cao Yang Chen Chunming Qiao 《Lightwave Technology, Journal of》2004,22(12):2722-2738
Optical burst switching (OBS) is a promising switching technology to exploit the potential benefits of optical communication and, at the same time, support statistical multiplexing of data traffic at a fine granularity. To quantify its benefits, the paper describes several typical burst assembly algorithms and studies their impact on the assembled burst traffic characteristics as well as the performance of TCP traffic. Also described is a proactive burst scheduling algorithm, called burst overlap reduction algorithm (BORA), which schedules locally assembled bursts in such a way as to reduce burst contention at downstream nodes in OBS networks. Furthermore, to provide analytical insights into performance evaluation of OBS networks, a burst loss model at an OBS node and its extension to different reservation protocols are presented. 相似文献
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In order to achieve service differentiation, especially loss differentiation, in optical burst switching (OBS) networks, we
propose a dynamic fiber delay line (FDL) partitioning algorithm, which divides FDLs into several groups over a feed-forward
output buffering architecture. In the proposed scheme, a plurality of traffic classes and FDL groups can be considered, and
each FDL group is assigned to traffic classes, so that the target loss probabilities of classes are guaranteed. Also, the
optimal number of FDLs for each FDL group by the proposed algorithm is decided in Poisson traffic environments. The extensive
simulation results validate the effectiveness of the proposed dynamic FDL partitioning algorithm for the loss differentiation
in OBS networks. 相似文献
7.
Control architecture in optical burst-switched WDM networks 总被引:27,自引:0,他引:27
Yijun Xiong Vandenhoute M. Cankaya H.C. 《Selected Areas in Communications, IEEE Journal on》2000,18(10):1838-1851
Optical burst switching (OBS) is a promising solution for building terabit optical routers and realizing IP over WDM. In this paper, we describe the basic concept of OBS and present a general architecture of optical core routers and electronic edge routers in the OBS network. The key design issues related to the OBS are also discussed, namely, burst assembly (burstification), channel scheduling, burst offset-time management, and some dimensioning rules. A nonperiodic time-interval burst assembly mechanism is described. A class of data channel scheduling algorithms with void filling is proposed for optical routers using a fiber delay line buffer. The LAUC-VF (latest available unused channel with void filling) channel scheduling algorithm is studied in detail. Initial results on the burst traffic characteristics and on the performance of optical routers in the OBS network with self-similar traffic as inputs are reported in the paper. 相似文献
8.
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
9.
Sheeshia S. Yang Chen Anand V. Chunming Qiao 《Selected Areas in Communications, IEEE Journal on》2004,22(8):1474-1482
This paper explores the feasibility of deploying optical burst switching (OBS) in metropolitan area networks (MANs) as an alternative to synchronous optical network (SONET), over wavelength-division multiplexing. We present a comparison between two OBS architectures (with centralized and distributed scheduling schemes), SONET, and next-generation SONET (NG-SONET), respectively. We quantify some of the performance metrics such as end-to-end delay and loss rate when supporting Ethernet traffic in metro ring networks. Our simulation results show that OBS offers significant performance improvement over SONET and NG-SONET. In general, the OBS architecture with distributed scheduling has a superior delay performance, whereas the OBS architecture with centralized scheduling has a better loss metric. 相似文献
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Daniel Morató Javier Aracil José Alberto Hernández José Luis García-Dorado 《Photonic Network Communications》2009,18(3):314-322
Given the bufferless nature of Optical Burst- Switched networks, data bursts are either transmitted or dropped; the latter
typically occurs when all the wavelengths of a given output port are occupied. Clearly, the amount of time during which a
given output port is blocked and cannot schedule incoming data bursts is a key performance measure of OBS networks. This work
shows that, under Poissonian burst arrivals, the blocking time distribution of a given output port in an OBS node approaches
the exponential distribution as the number of wavelengths increases. It is further shown that this behavior remains regardless
of the size distribution of incoming bursts, and therefore, regardless of the burst-assembly algorithms employed at the border
nodes. Finally, this result is also applied to the characterization of the amount of overspill traffic, that is, the number
of bursts that arrive within a blocked period, and therefore must be either dropped or diverted over alternative routes. 相似文献
12.
Optical switching technology can be categorized into optical circuit switching (OCS), optical packet switching (OPS) and optical burst switching (OBS). OCS is suitable for large amounts of data transmission; however, the channel utilization is inefficient when the traffic flows are intermittent. OPS can be easily adapted to any higher layer and is suitable for bursty traffic, but it requires a highly complex technology and optical buffer. The new switching paradigm, OBS, can provide higher bandwidth utilization and meanwhile avoid the complexity in OPS technology.In this paper, we investigate how the quality of service (QoS) can be guaranteed and reliable transmission can be supported in the OBS-based Internet backbone. We propose the adjustable-time-counter-based (ATCB) burst assembly and the non-real time packet retransmission mechanisms and apply them in the ingress router of the OBS Internet backbone to guarantee the quality of real time applications and lossless requirement of non-real time services. Moreover, traffic shaped is performed for real time packets in the egress router so that the real time property is preserved with a low jitter. Simulation results show that the burst blocking probability using the ATCB burst assembly is improved, compared with the time-counter-based (TCB) and burst-length-threshold-based (BLTB) mechanisms. The delay, loss and jitter of real time service conform to the QoS requirement. Meanwhile, the delay of non-real time service also falls in the acceptable range. 相似文献
13.
In this article, we study the blocking probability in a wavelength division multiplexing (WDM) based asynchronous bufferless
optical burst switched (OBS) network, equipped with a bank of wavelength converters. Our analysis encloses two wavelength
reservation schemes JIT (just-in-time) and JET (just-enough-time), and two-class data rate. The contribution of our work includes:
(i) derivation of an accurate model for blocking probability of lower priority bursts in case of a non-preempted model; (ii) provision of the analytical model for blocking probability calculation in the OBS network, which includes these
variables: two signaling schemes, partial wavelength conversion, two-class data, traffic intensity, cross-connect speed, number
of wavelengths in WDM fiber, number of fibers in the node, number of wavelength converters, and number of nodes in the path;
(iii) simulation results, which show that partial wavelength conversion provide quite satisfactory quality of service. We
compare performance in a single OBS node, under various sets of parameter values. The OBS network shows great flexibility
in terms of used multiclass data, and there is no dependence on the used higher layer protocol. 相似文献
14.
The performance of Optical Burst Switched (OBS) networks is compared to that of Optical Circuit Switched (OCS) networks in terms of bandwidth efficiency. Two traffic flow models are employed to investigate the effects of traffic grooming, packetization, buffering and burst assembly on bandwidth efficiency and utilization. Traffic is represented by fluid-flow continuous bit streams in the first model and by packet-based discrete flows in the second model. It is shown that the parameters of traffic characteristics and burst assembly have significant impact on the relative bandwidth savings of OBS. The bandwidth efficiency of OBS compared to OCS should not be taken for granted and has to be examined carefully on a case by case basis. 相似文献
15.
Kyriaki Seklou Angeliki Sideri Panagiotis Kokkinos Emmanouel Varvarigos 《Optical Switching and Networking》2013,10(2):132-148
We propose new burst assembly schemes and fast reservation (FR) protocols for Optical Burst Switched (OBS) networks that are based on traffic prediction. The burst assembly schemes aim at minimizing (for a given burst size) the average delay of the packets incurred during the burst assembly process, while the fast reservation protocols aim at further reducing the end-to-end delay of the data bursts. The burst assembly techniques use a linear prediction filter to estimate the number of packet arrivals at the ingress node in the following interval, and launch a new burst into the network when a certain criterion, different for each proposed scheme, is met. The fast reservation protocols use prediction filters to estimate the expected length of the burst and the time needed for the burst assembly process to complete. A Burst Header Packet (BHP) packet carrying these estimates is sent before the burst is completed, in order to reserve bandwidth at intermediate nodes for the time interval the burst is expected to pass from these nodes. Reducing the packet aggregation delay and the time required to perform the reservations, reduces the total time needed for a packet to be transported over an OBS network and is especially important for real-time applications. We evaluate the performance of the proposed burst assembly schemes and show that a number of them outperform the previously proposed timer-based, length-based and average delay-based burst assembly schemes. We also look at the performance of the fast reservation (FR) protocols in terms of the probability of successfully establishing the reservations required to transport the burst. 相似文献
16.
Presently, optical burst switching (OBS) technology is under study as a promising solution for the backbone of the optical Internet in the near future because OBS eliminates the optical buffer problem at the switching node with the help of no optical/electro/optical conversion and guarantees class of service without any buffering. To implement the OBS network, there are a lot of challenging issues to be solved. The edge router, burst offset time management, and burst assembly mechanism are critical issues. In addition, the core router needs data burst and control header packet scheduling, a protection and restoration mechanism, and a contention resolution scheme. In this paper, we focus on the burst assembly mechanism. We present a novel data burst generation algorithm that uses hysteresis characteristics in the queueing model for the ingress edge node in optical burst switching networks. Simulation with Poisson and self‐similar traffic models shows that this algorithm adaptively changes the data burst size according to the offered load and offers high average data burst utilization with a lower timer operation. It also reduces the possibility of a continuous blocking problem in the bandwidth reservation request, limits the maximum queueing delay, and minimizes the required burst size by lifting up data burst utilization for bursty input IP traffic. 相似文献
17.
光突发交换网络中一种基于负载平衡的路由机制 总被引:1,自引:1,他引:1
光突发交换(OBS)是实现下一代光互联网技术中的一种极具前景的方案.OBS网络中采用的路由机制多是最短路径优先的路由选择机制,这种路由机制本身的缺陷会使网络有较大的阻塞概率,不能实时反映网络流量的变化,同时对不同的网络拓扑的适应性较差.本文提出了一种OBS网络中能实现负载平衡的路由机制,对一个请求选择一条可以使网络中各链路使用波长数的统计方差最小的路由.仿真结果表明,该方法在阻塞概率方面要优于最短路径路由机制;而在传输延迟性能方面接近于最短路径路由机制,同时对于不同的网络拓扑以及节点流量的变化都具有一定的适应性. 相似文献
18.
Mounire El Houmaidi Mostafa A. Bassiouni Guifang Li 《Photonic Network Communications》2007,13(1):111-122
In this paper, we combine fiber delay lines (FDL) and optical wavelength conversion (OWC) as the solution for the burst contention problem in optical burst switching (OBS). We present a placement algorithm, k-WDS, for the sparse placement of FDLs at a set of selected nodes in the network. The algorithm can handle both uniform and non-uniform traffic patterns. Our extensive performance tests show that k-WDS provides more efficient placement of optical fiber delay lines than the well-known approach of placing the resources at nodes with the highest experienced burst loss. Performance results are also given to compare the benefit of using FDLs alone, OWCs alone, as well as a mixture of both FDLs and OWCs. A new algorithm, A-WDS, for the placement of an arbitrary numbers of FDLs and OWCs is presented and evaluated under different uniform and non-uniform traffic loads using network simulation of the NSFNET topology and randomly generated graphs. The paper is concluded by presenting the design of a cost-effective optical switch equipped with variable-delay FDL bank. Based on the switch design, a scheme to provide differentiated services for multiple classes of traffic is presented and evaluated. 相似文献
19.
Ingress nodes in optical burst switching (OBS) networks are responsible for assembling burst from incoming packets and forwarding these bursts into the OBS network core. Changes in the statistical characteristics of a traffic stream at an ingress switch can affect the capacity of the network to provide quality of service. Therefore, the statistical characteristics of the output flow of an ingress node must be known for appropriate network dimensioning. This paper evaluates the impact of burst assembly mechanisms on the scaling properties of multifractal traffic flows. Results show that the factor most relevant in determining the nature of the output traffic flow is the relationship between the cut-off time scale of the input traffic and the time scale of assembly threshold. Moreover, a procedure for the detection of the cut-off scale of incoming traffic is introduced. 相似文献
20.
《IEEE network》2000,14(6):48-53
Wavelength-division multiplexing has emerged as an important physical layer technology. Optical transmission provides a physical layer capable of carrying bits at the speed at the order of a gigabit per second. Optical burst switching is proposed to overcome the shortcomings of conventional WDM deployment, such as lack of fine bandwidth granularity in wavelength routing and electronic speed bottlenecks in SONET/SDH. We describe an architecture for IP network over the OBS WDM transmission core. The use of MPLS-type technique for forwarding data bursts and the inclusion of a medium access control layer between the optical (WDM) and IP layers are the key ingredients of the proposed architecture. In particular, the architecture is based on provisioning MPLS paths, also called label switched paths, of desired quality of service through the OBS WDM transmission core. The MAC layer performs various OBS-specific functions, such as burst assembly, burst scheduling, and offset setting/traffic shaping. While burst assembly and burst scheduling are relatively straightforward, we point out that the offset setting strategy has significant impact on the performance of IP network operating over OBS WDM core. We describe a shaping scheme to set the offset, an important system parameter for OBS, between the successive data bursts of a given data stream (label switched path) and their associated control packets. This scheme results in robust operation of the network and also facilitates traffic engineering. Guidelines are provided for implementing various IP QoS mechanisms in the optical backbone using OBS. 相似文献