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1.
Optical burst switching (OBS) presents itself as a promising technology for bridging the gap between optical wavelength switching
and optical packet switching. Increasingly, researchers attempt to incorporate more realistic constraints into the design
of OBS networks. Optical signal transmission quality is subject to various types of physical impairment introduced by optical
fibers, switching equipment, or other network components. The signal degradation due to physical impairments may be significant
enough such that the bit-error rate of received signals is unacceptably high at the destination, rendering the signal not
usable. In this paper, based on earlier work, we study the burst scheduling problem in OBS networks, taking into account physical
impairment effects. We propose three effective burst scheduling algorithms: (1) a JET based Physical Impairment Constrained
Algorithm (JETPIC), (2) an Integrated Physical Impairment Constrained Algorithm (IPIC), and (3) an Enhanced Integrated Physical
Impairment Constrained Algorithm (EIPIC). At an OBS node, the proposed algorithms schedule bursts for transmission by searching
for available resources as well as verifying signal quality. Our simulation results show that the proposed algorithms are
effective in terms of reducing the burst blocking probability. In general, algorithm JETPIC outperforms algorithms IPIC and
EIPIC in burst blocking probability and average end-to-end delay performance.
相似文献
Bin WangEmail: |
2.
Nuno M. Garcia Paulo P. Monteiro Mrio M. Freire Jos R. Santos Przemyslaw Lenkiewicz 《Optical Switching and Networking》2007,4(3-4):173-188
The new architectural approach to Optical Burst Switching networks presented here features a common control channel and a node locally maintained network model. The Common Control Channel allows for a fast and efficient broadcast of the network Control Packets, which in turn are used by every node to update its Local Network Model. The Local Network Model allows efficient network resource planning as each node is aware of the reservation status intentions for the resources on each node. This paper describes the new C3-OBS architecture, evaluates its comparative performance to regular OBS, assesses the manageable bandwidth for a C3-OBS network and evaluates the common control channel manageable load. The concept of “Well-Informed Node” is defined as a metric of trustfulness on the information managed by the Local Network Model and the scope and application of C3-OBS networks are studied. 相似文献
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Chrisoula Papazoglou Panagiotis G. Sarigiannidis Georgios I. Papadimitriou Andreas S. Pomportsis 《International Journal of Communication Systems》2010,23(2):187-203
In an optical burst switched network, variable‐sized data bursts are switched on the fly using bandwidth previously reserved by their control packets. A key problem in OBS networks is the assignment of wavelengths to incoming bursts, that is, the scheduling of bursts. This paper proposes a new class of burst scheduling algorithms based on a triangular estimator. The proposed tool reduces the complexity of the scheduling scheme (measured in channel checks) without compromising its performance (measured by the burst drop ratio). Simulation results demonstrate both the accuracy and the efficiency of the estimator in a variety of scenarios and under self‐similar network traffic. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
7.
Sheng Huang Keping Long Xiaolong Yang Qianbin Chen Yun Li 《Photonic Network Communications》2009,18(1):49-54
Optical burst switching (OBS) is a promising switching paradigm for building the next generation optical internet. The proportional
differentiation model is very convenient for network operators to quantitatively adjust the quality differentiation among
service classes. To provide proportional differentiated services for OBS networks, a proportional differentiation scheme based
on batch scheduling is proposed in this article. The scheme adopts the batch scheduling idea to reserve data channel resources
for a batch of data bursts. It helps to decrease burst dropping probability. When some data bursts are unsuccessfully scheduled,
a preemption method is used to keep a proportional burst dropping probability among service classes according to the expected
burst dropping probability equations given by the proportional differentiation model. The scheme has low computational complexity.
Simulation results show that the scheme can provide proportional differentiated services and efficiently decrease the burst
dropping probability.
相似文献
Keping LongEmail: |
8.
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
9.
In the past years, several signaling protocols were proposed for OBS networks and the most popular one is the Just-Enough-Time
(JET) protocol. JET not only efficiently utilizes the network capacity, but also effectively reduces the end-to-end transmission
delay. However, the most critical defect of JET is its intrinsic deficiency: Fairness. The fairness problem is a traditional
problem common to various kinds of networks. It results in a phenomenon that bursts with a shorter number of hops are generally
favorized and hence deteriorates the network utilization as well. In this article, we investigate this problem and propose
a fair channel scheduling algorithm as a solution. Usually there is a tradeoff between fairness and blocking performance.
Accordingly, the objective of our scheme is to achieve a balance between the two conflicting metrics as much as possible.
In our scheme, each burst is associated with a dynamic priority which is defined by several characteristics of the burst.
When contention occurs, the proposed scheme picks the preferable burst and drops the other one according to their priorities.
From simulation results, we observed that the proposed scheme could improve fairness without causing significant reduction
in dropping performance. Furthermore, it increases the effective link utilization as well.
相似文献
Ching-Fang HsuEmail: |
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Existing performance studies on optical burst switched (OBS) networks have been focusing on channel blocking, i.e., when the required wavelength is not available on a link along a burst’s route. However, we identify another type of
blocking as the receiver blocking, i.e., when the receiver at a burst’s destination node is occupied by another burst. Receiver blocking may account for the
much larger part of total burst blocking. Receiver blocking has been largely ignored in existing research. In this paper we propose using multiple receivers or fiber delay lines (FDL)
in front of the receivers in order to reduce the receiver blocking probability. Extensive simulation results on bi-directional
OBS rings are presented to illustrate the problem and the performance of our proposed approaches. The results indicate that
receiver blocking can be almost eliminated by using as little as three receivers and can be reduced by using a FDL of small
length. To our knowledge, this is the first performance study that covers both channel and receiver blocking for OBS networks. 相似文献
12.
The most important design goal in Optical Burst Switching (OBS) networks is to reduce burst loss resulting from resource contention.
Especially, the higher the congestion degree in the network is, the higher the burst loss rate becomes. The burst loss performance
can be improved by employing an appropriate congestion control. In this paper, to actively avoid contentions, we propose a
dynamic load-aware congestion control scheme that operates based on the highest (called ‘peak load’) of the loads of all links
over the path between each pair of ingress and egress nodes in an OBS network. We also propose an algorithm that dynamically
determines a load threshold for adjusting burst sending rate, according to the traffic load in a network. Further, a simple
signalling method is developed for our proposed congestion control scheme. The proposed scheme aims to (1) reduce the burst
loss rate in OBS networks and (2) maintain reasonable throughput and fairness. Simulation results show that the proposed scheme
reduces the burst loss rate significantly, compared to existing OBS protocols (with and without congestion control), while
maintaining reasonable throughput and fairness. Simulation results also show that our scheme keeps signalling overhead due
to congestion control at a low level. 相似文献
13.
《AEUE-International Journal of Electronics and Communications》2014,68(1):44-50
In optical burst switching (OBS) networks, burst contentions in OBS core nodes may cause data loss. To reduce data loss, retransmission scheme has been applied. However, uncontrolled retransmission may increase network load significantly and data loss probability defeating the retransmission purpose. In addition, in a priority traffic existing OBS network, OBS nodes may apply different retransmission mechanisms to priorities bursts for quality-of-service (QoS) support. This study has developed a controlled retransmission scheme for prioritized burst segmentation to support QoS in OBS networks. Unlike previous works in the literature, we have set a different value to retransmission probability at each contention and propose a retransmission analytical model for burst segmentation contention resolution scheme. In addition, we have applied the proposed retransmission scheme to the prioritized burst segmentation for QoS support. We have taken into account the load at each link due to both fresh and retransmitted traffic, and have calculated the path blocking probability and byte loss probability (ByLP) for high-priority and low-priority burst to evaluate network performance. An extensive simulation has been proposed to validate our analytical model. 相似文献
14.
Optical burst switching (OBS) networks have been receiving much attention as a promising approach to build the next generation
optical Internet. In the bufferless DWDM switching technology, burst loss that should be minimized is the key design parameter.
One of the critical design issues in OBS network is how to plan the optimal routing path in order to minimize burst dropping
due to network resource contention. This study proposes the burst frequent-pattern tree (BFP-Tree) approach to pre-determine
a suitable routing path in the OBS network. The BFP-Tree approach essentially is a learning-based mechanism that is able to
determine a suitable transmission path from the historical network transaction data. The experiment results show that the
successful rates of routing paths obtained by the BFP-Tree approach are able to converge to those of the optimal results.
相似文献
Zen-Der ShyuEmail: |
15.
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
16.
针对光突发交换(OBS)网络中已有的包括抢占和波长分离等服务质量(QoS)保证机制的不足,提出了一种改进的基于QoS的标签交换路径共享(QLS)算法。算法通过链路波长资源的统计复用,在保证高优先级业务传送的可靠性和有效性的同时,提升低优先级业务的QoS性能。使用开源离散事件仿真软件OMNeT++搭建了OBS/GMPLS仿真平台,对4×4对称型MESH网络和NSFNET网络分别采用WP算法和QLS算法进行了仿真。结果表明,QLS算法对于高QoS等级业务性能影响极小,MESH和NSFNET网络中class3业务的丢包率分别减少了近0.2和0.3,平均丢包率分别减少了约0.05和0.1。 相似文献
17.
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
18.
Jin-An Chen Ruay-Shiung Chang 《International Journal of Wireless Information Networks》1995,2(2):61-70
A distributed algorithm for the conflict-free channel allocation in CDMA (code division multiple access) networks is presented. Dynamic adjustment to topological changes is also considered. Though the schedules produced by our algorithm are not optimal with respect to link schedule length, the algorithm is simple and practical. The link schedule length minimization problem is NP-complete. Here the length of a link schedule is the number of time slots it uses. The algorithm guarantees a bound 2 — 1 time slots on the TDMA cycle length, where is the maximum degree of a station (i.e., maximum number of stations that a station can reach by radio links) in the network. The message complexity of a station isO(). 相似文献
19.
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
20.
根据光突发交换(OBS)网络核心节点的结构和功能 特点,分析了OBS网络核心节点的数据信道 调度算法,提出了一种新的基于标记可抢占调度算法(LPSA),并讨论和分析了算法的实 现过程。本文算法根据到达核心节点的控制包所属业务等级的突发数据(OB)包占用的网络带 宽决定 数据信道调度的方法,实现了合理的使用数据信道和各业务类别间的业务区分,最终达到改 善OBS网络性能的目的。 相似文献