一种改进的光突发交换数据信道调度算法

简单介绍了两类基于LAUC的OBS数据信道调度算法-重新调度算法和成组调度算法,分析了其优缺点.分析了在LAUC机制下产生不合理调度的原因,并在此基础上提出了一种新的改进的数据信道调度算法,可以在付出相对较小代价的情况下减少丢包率,提高信道利用率,使信道调度趋于合理.     

光突发交换网络中一种基于LAUC的批调度算法

为了降低突发丢失率和调度复杂度,提出了一种基于LAUC的批调度算法.该算法首先缓存多个突发控制包,当最大缓存时间到达时,根据突发到达顺序批调度处理缓存中的突发控制包,并采用LAUC算法来为突发预留信道资源.其优势在于:计算复杂度与LAUC一样低,因为它只增加了突发控制包缓存和改变了LAUC算法的调度顺序;突发丢失率比较低,仿真结果表明它的突发丢失率比LAUC算法要低,当最大缓存时间大于偏置时间的最大差值时,它的突发丢失率比LAUC-VF算法还要低.     

一种用于光突发交换网络的队列调度算法

提出一种突发控制分组队列的最小偏置时间调度算法,并通过建立模型对该算法和先进先出队列FIFO的性能进行了仿真比较,仿真结果表明该算法能够尽量减小突发控制分组在路由器队列中的阻塞,减小了突发控制分组的节点延时,从而降低了丢包的可能性,提高了网络的吞吐量。     

基于阈值的光突发交换网络数据信道调度算法

光突发交换(OBS)是实现下一代光互联网中的一种极具前景的方案。该文提出了一种基于阈值的OBS网络数据信道调度算法,对于长度大于阈值的光突发数据包采用LAUC算法进行调度,对于长度小于阈值的光突发数据包采用LAUC-VF算法进行调度。仿真结果表明,该算法在调度时间方面与已有的LAUC算法很接近;而在光突发数据包丢失率性能方面要优于LAUC-VF算法。     

一种改进的光突发交换调度算法研究

数据信道调度是OBS核心路由器的关键技术之一,文章对数据信道的几种调度算法进行了分析.在此基础上,介绍了一种改进的波长调度算法.网络仿真结果表明,该算法可以有效改善网络性能.     

混合光突发交换网络的研究

提出了一种新的混合光突发交换（HOBS）网络，并且使用环网对网络进行了仿真比较研究。仿真结果表明HOBS的丢包率远低于OBS，并且下降的程度决定于拆分比例、缓存的大小以及节点的处理速率等参数。     

光突发交换网络的突发包组装和调度

光突发交换(OBS)由于结合了光线路交换和光分组交换的优点并且改进了两者的不足之处,成为实现IP over WDM的重要手段。主要研究实现光突发包在边缘路由器的组装生成和调度机制。通过模拟的方法研究边缘路由器的输出性能,包括输出流量的形状和时延特性。结果显示,不同服务等级的时延要求可以通过组装控制输出流的最大时延得以保证。同时边缘路由器组装和分配信道缓冲区设置和优先分配机制可以影响到输出光突发包的长度和突发度。     

光突发交换数据调度模块的硬件实现

以ALTERA公司CYCLONEⅡ系列的FPGA芯片为硬件平台,使用quartusⅡ进行编译、综合和下载,一种光突发交换(OBS)网数据调度模块实现了。该方案采用Round-Robin算法对突发包的调度请求进行轮询,根据最近可用未占用信道算法(LAUC)对突发包进行信道选择。仿真结果表明了该实现方案的有效性。     

一种新的应用于光突发交换网络保证流量均衡的波长调度算法

在现有波长调度方法(LAUC_VF)的基础上,结合跳数优先级技术和动态资源分配技术,提出了一种新的可以提供流量均衡的波长调度算法(HP_JET)。通过仿真,证明这种波长调度算法在改善全网阻塞率以及均衡流量方面比原有的波长调度算法有更好的性能。     

基于窗口的光突发交换调度算法

针对光突发交换网(OBS)中的资源竞争和QoS支持等问题，提出了一种新型的基于窗口的调度算法。该算法利用边缘节点的电缓存，对调度窗口中的突发数据包进行批量BORA调度，可以有效地降低网络中发生资源竞争的概率；同时调度窗口中的优先级策略还可以进一步增强QoS。网络仿真结果表明，通过选择合适的调度窗口和最大允许时延，该调度算法在0．8的网络负载下使得高优先级突发数据包的阻塞率下降一个量级，信道利用率提高3．5％。     

OBS网络中改进的重调度算法

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.文章在重调度算法的基础上首次提出了一种改进的重调度算法,通过一次性搜索保存数据信道信息,减少了重调度处理的次数与复杂性,并能降低系统的丢包率.     

A tree-based slot allocation algorithm for loss-free slotted OBS networks

Optical burst switching (OBS) is regarded as one of the most promising switching technologies for next generation optical networks. However, the data burst contention problem is still unresolved thoroughly even though slotted OBS (SOBS) is studied as a new paradigm reducing the blocking rate. In this article, we propose a tree-based slot allocation (TSA) algorithm for loss-free SOBS networks, where the TSA algorithm originally avoids contention of the time-slots by reserving the time-slots with different time-slot positions for the source nodes, respectively. In order to manage the time-slots efficiently, we also propose an OBS superframe, which is a cyclic period and consists of multiple time-slots transmitted by the source nodes toward the same incoming port of a destination node. In addition, we attempt to optimize multiplexing of the OBS superframes to reduce wavelength consumption. On the other hand, when incoming traffic is beyond expectation, a source node may need more time-slots to prevent packet loss because of buffer overflow. For reallocation of the time-slots, we propose a flow control scheme managing some number of shared time-slots, where a control node adaptively allocates (or redeems) the time-slots to (or from) source nodes by utilizing the shared time-slots based on fluctuating traffic condition. Simulation results show that the blocking rate of the proposed TSA–OBS scheme is zero with acceptable queueing delay at moderate traffic offered loads. In addition, multiplexing optimization simulated in the 14-node NSFNET achieves a 63% reduction of wavelength consumption. Moreover, the proposed flow control scheme assisting the TSA algorithm maintains a target upper-bound of queueing delay at the source node, so that packet loss caused by buffer overflow is prevented.     

Long-term estimation-based burst control algorithm in OBS networks

By taking advantage of statistical multiplexing gain in the burst level, optical burst switching (OBS) technology enables optical Internet to handle huge volume of data in an efficient manner without requiring optical buffers in the optical domain. However, when congestion builds up in the optical network core, large amount of data might be lost. In this article, we propose an efficient optical burst control algorithm that operates based on the awareness of future burst traffic condition to eliminate the effect of congestion reaction delay. The proposed algorithm takes advantage of multiple statistics to improve the estimation accuracy.Through performance evaluation, it is verified that the proposed algorithm proactively controls inbound burst traffic so that the OBS network can stay in a stable traffic condition while keeping the network throughput high.

OBS中的一种原波长优先批调度算法

光突发交换网络(OBS)中心节点使用波长转换器减少突发丢失率,但波长转换器价格昂贵且技术不成熟,中心节点需要减少波长转换器的使用数目.大部分数据信道调度算法都没有考虑波长转换器数目.为此,提出一种原波长优先批调度算法基于相同波长转换器数目下进一步减少突发丢失率.仿真结果表明,这种批调度算法在波长转换器不足条件下,与其它...     

OBS网络中的最小间隙组调度算法

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.     

一种基于混合门限的快速前向资源预留OBS组装算法

研究了一种以突发组装的时间门限与包长门限的乘积为混合门限的按照步长大小进行自适应调整的突发组装算法,并且当第一个IP包进入组装队列时就对突发的大小及组装时间进行预测,最大程度上降低了端到端的延迟;仿真结果表明,在进行快速前向资源预留组装的基础上引入重传机制,可以在减少端到端延时的同时降低突发丢包率,较大地提高了OBS网络的性能.     

OBS网突发包竞争问题的解决方案

光突发交换(OBS)是近几年出现的一种很有前途的新型光交换技术。由突发包之问竞争所导致的数据丢失是光突发交换网络所面临的一个重要问题，它影响到光突发交换能否走向实用化。为此提出了一种用于解决突发包之间竞争钧综合方案，并对它的性能进行了仿真研究。仿真结果表明，该方案可以大幅度地降低OBS网络中的数据丢失事。     

基于虚拟突发的OBS数据信道重调度算法研究

基于虚拟突发的概念,提出了一种新的光突发交换(OBS)数据信道重调度算法,即(WCRA-VB).新算法一方面有效地克服了传统OBS网络中数据突发(DB)与控制分组(BHP)到达顺序不一致带来的问题,另一方面极大地增强了数据块重调度的灵活性.仿真结果表明:与传统OBS重调度算法(其重调度粒度为常规突发)和原虚拟突发调度方案相比较,本文的WCRA-VB算法具有以下优势:既能有效改善网络总的丢包率,也能提高链路利用率,同时具有很强的灵活性.     

A framework for deterministic delay guarantee in OBS networks

In OBS networks, the delay of control packets in the switch control unit (SCU) of core nodes influences burst loss performance in the optical switching and should be constrained. Furthermore, the end-to-end (E2E) delay requirements of premium services need queueing delay guarantee in network nodes throughout the transmission path. For this purpose, a framework for deterministic delay guarantee is proposed in this article. It incorporates the deterministic delay model in the ingress edge node as well as in the SCUs of core nodes. On this basis, the configuration of the assembler and the offset time is addressed by means of an optimization problem under the delay constraints. Scenario studies are carried out with reference to realistic transport network topologies. Compared to statistical delay models in the literature, the deterministic model has advantages in rendering robust absolute delay guarantee for individual FEC flows, which is especially appreciated in the provisioning of premium services. By performance evaluation in comparison with the statistical models, it is shown that the adopted deterministic delay models lead to practical delay bounds in a magnitude that is close to the delay estimations by stochastic analysis.