采用偏射路由算法的全光分组网络的性能分析

本文提出采用统一的马尔可夫链方法分析存储转发路由和偏射路由算法的网络，并在具体计算偏射概率时，采用了递推的算法。着重分析了偏射路由算法在无存储器、有单个存储器及有两个存储器的情况下，ＭａｎｈａｔｔａｎＳｔｒｅｅｔＮｅｔｗｏｒｋ和ＳｈｕｆｌｅＮｅｔ网络的性能，包括网络吞吐量、数据包的平均跳转次数和数据包跳转次数的概率分布，并对ＭａｎｈａｔａｎＳｔｒｅｅｔＮｅｔｗｏｒｋ和Ｓｈｕｆ－ｆｌｅＮｅｔ两种网络进行了简单的比较。     

一种基于门限的光突发交换受限偏射路由算法

提出了一种基于突发丢失门限的条件偏射路由算法（LDFD），该算法采用丢弃少量偏射的高优先级突发来保证偏射路由上较低优先级非偏射突发的服务质量（QoS）。当偏射的高优先级突发到达核心节点而该节点没有空闲数据信道时，就启用定义的偏射条件检测函数来判断是丢弃该突发还是允许其抢占非偏射的低优先级突发的资源，从而减少偏射突发与偏射路由上原有突发的竞争。仿真表明，该算法可以很好地控制偏射突发对偏射路由上正常流量的影响，并有效地提高整个网络的突发丢失性能。     

基于竞争控制的光突发交换条件偏射路由算法

光突发交换(OBS)网络中,偏射路由算法是有效地解决突发竞争、提高网络性能的一种重要措施,但通过分析发现,它可能会导致偏射路由上正常(非偏射)突发的丢失率上升.提出了一种基于竞争控制的条件偏射路由算法,根据定义的偏射条件检测函数,有条件的偏射或丢弃竞争突发来保证偏射路由上正常突发的QoS.仿真表明该算法可以很好地控制偏射突发对网络偏射路由上正常流量的影响.     

基于阈值检测的光突发交换偏射路由算法

光突发交换是适合在当前技术条件下的新交换技术,它比电路交换灵活,带宽利用率高,又比光分组交换易于实现,将成为下一代光IP骨干网的核心技术。在光突发交换网络中,偏射路由算法是有效解决突发竞争、提高网络性能的一种重要措施。首先分析了发送端控制的偏射路由技术,在此基础上提出了一种基于阈值检测的偏射路由的改进算法。该算法通过跳数来控制无效偏射路由并通过有条件地丢弃偏射突发来保证正常突发的丢包率,从而减少偏射路由对网络负荷的影响,使整个网络的丢包率得到一定提高,改善网络性能。     

OBS中基于优先级与负载均衡的偏射路由算法

为了解决偏射算法在偏射控制七的问题,提出了一种基于优先级与负载均衡的偏射路由算法.当冲突发生时,分割优先级低的突发数据包;将冲突部分的突发包偏射到空闲的链路上,并在空闲的链路中选择若干条"当前最大剩余跳数小于源-目的节点的最大跳数"的路由作为候选路由;最后,在这些候选路由中选择一条可以使网络中各链路使用波长数的统计方差...     

OBS网络中基于拥塞避免的提前偏射路由研究

突发竞争是OBS(光突发交换)网络需要解决的关键问题,偏射路由作为一种有效的竞争解决方案而被广泛研究。文章提出了一种基于拥塞避免的提前偏射路由算法,利用周期性反馈的网络拥塞信息按一定概率提前偏射部分突发包。与传统的最短偏射路由算法相比,本算法达到了避免拥塞以及均衡网络负载的目的。仿真结果表明:文章所提算法在突发丢失率、吞吐量以及平均链路利用率方面性能都有所提高。     

OBS中基于奖惩机制的偏射路由研究

偏射路由作为一种行之有效的光突发交换竞争解决机制而被广泛加以研究,文章提出了一种改进的基于奖惩机制的偏射路由算法,通过查找代表链路实时拥塞状况的奖惩列表,选择负载最小的链路对竞争的突发包进行偏射处理,与传统的固定最短偏射路由算法相比,本算法达到了均衡网络负载的目的。仿真结果表明：本文所提出的算法在突发丢失率及平均链路利用率方面性能都有所提高。     

基于链路负载的光突发交换混合路由算法

偏射路由和丢弃重传都能够有效解决光突发交换(OBS)网络中的突发竞争问题.结合偏射路由和丢弃重传的优点,提出了一种基于链路负载的偏射和重传混合的路由算法(LHDR).它根据网络链路的流量负载来计算和存储偏射路由,同时通过链路的平均负载率和节点跳数来确定对竞争突发的偏射或重传.仿真结果表明,LHDR在网络流量负载很高的情况下,能获得很好的突发丢失和端到端延时性能.     

支持业务均衡的OBS网络分布式回退偏射路由算法

突发竞争是引起光突发交换(OBS)网络丢包的主要因素之一,而作为一种有效的突发竞争解决方法的偏射路由,因其对光缓存器的性能和数量要求较低而备受关注。然而,现有偏射路由算法忽略了偏射业务对偏射路径上原有业务的影响以及业务被偏射后自身的成功传输率,同时也忽略由偏射引起的偏置时间不够的问题,致使OBS网络整体丢包率较高。为此,本文提出了一种支持业务均衡的分布式回退偏射路由算法(DBDF-LB),基本思路在于:从全网业务均衡出发,根据网络状态信息分布式的为偏射业务选择一条丢包率最小、跳数最短的路径;然后通过回退机制,利用网络资源来缓存突发包,从而补偿由偏射引起的额外偏置时间。与典型的最短路径偏射算法(SPDF)相比,DBDF-LB能有效降低丢包率约23~50%,而成功传输突发包所经历的平均跳数增加不到1跳。     

光突发交换网络中的偏射路由算法

首先对偏射路由算法的基本概念、竞争解决机制及其优缺点进行了论述,针对其存在的缺陷详细分析了两种改进的偏射路由算法,重点研究了改进的偏射路由算法的实现机制,并对今后偏射路由算法的研究重点和发展趋势表达了作者的观点。     

OBS网络的偏射路由研究

文章分析了偏射路由对网络性能的影响,在分析发送端控制偏射路由技术的基础上,提出了基于阈值检测和数据更新的改进方案.边缘节点快速更新状态信息,并通过特殊控制分组传递链路拥塞的分布特征等信息;交换节点进行阈值检测,动态决定竞争时突发的传送方式,减少偏射路由对网络负荷的影响,进一步降低网络阻塞率,改善网络性能。     

Sharp approximate models of deflection routing in mesh networks

Deflection routing is a simple, decentralized, and adaptive method for routing data packets in communication networks. The focus of this work is on deflection routing in the Manhattan street network (a two-dimensional directed mesh), although the analytic approach should apply to any regular network. Two approximate performance models that give sharp estimates of the steady-state throughput and the average packet delay for packets admitted to the network are presented. The results of extensive simulation experiments are reported, which corroborate the models' predictions. The results show that deflection routing is very effective. Two measures of the merit of a network for deflection routing are its diameter and its deflection index. Networks are presented whose diameter and deflection index are near the optimal values     

Mini‐Slot‐Based Transmission Scheme for Local Customer Internetworking in PONs

We propose a new mini‐slot transmission scheme for a passive optical network (PON) in which each customer can be switched either to access mode or to internetworking mode dynamically. In this paper, we present the system implementation (called LAN‐PON) as well as the performance of the proposed transmission scheme to illustrate its feasibility and benefits. A mini‐slot scheme can rapidly reduce the queuing delay, which increases due to the flooding of the deflected packets in a deflection scheme. We evaluate the impact of mode switching time on the bandwidth gain (throughput) and delay of local area network (LAN) traffic in the LAN‐PON with a mini‐slot scheme. We also analyze a theoretical delay model of the proposed scheme. The simulation results demonstrate that switching time has an impact on LAN performance, and the average packet delay of the proposed scheme is significantly improved compared to that of the deflection scheme.     

Deflection routing in IP optical networks

This paper deals with optical packet switching in a full-IP transport network scenario. Given the technological limits of accomplishing packet buffering in the optical domain, deflection routing is here explored as an alternative technique for resolving packet contentions without buffering packets. Two different network topologies have been considered here, that is a regular six-node network with different connectivity factors and the classical NSF network. A limited amount of optical buffering is considered in the switching nodes that performs both input queuing and shared queuing of packets to be switched. The performance improvements that can be obtained by deflection routing have been evaluated considering different methods for choosing the alternative paths where to deflect packets that cannot be transmitted onto the shortest path to the addressed destination.     

Packet scheduling algorithms and performance of a bufferedshufflenet with deflection routing

In a multihop network, packets go through a number of hops before they are absorbed at their destinations. In routing to its destination using minimum path, a packet at a node may have a preferential output link (the so-called “care” packet) or may not (the so-called “don't care” packet). Since each node in an optical multihop network may have limited buffer, when such buffer runs out, contention among packets for the same output link can be resolved by deflection. In this paper, we study packet scheduling algorithms and their performance in a buffered regular network with deflection routing. Using shufflenet as an example, we show that high performance (in terms of throughput and delay) can he achieved if “care” packets can be scheduled with higher priority than “don't care” packets. We then analyze the performance of a shufflenet with this priority scheduling given the buffer size per node. Traditionally, the deflection probability of a packet at a node is solved from a transcendental equation by numerical methods which quickly becomes very cumbersome when the buffer size is greater than one packet per node. By exploiting the special topological properties of the shufflenet, we are able to simplify the analysis greatly and obtain a simple closed-form approximation of the deflection probability. The expression allows us to extract analytically the performance trend of the shufflenet with respect to its buffer and network sizes. We show that a shufflenet indeed performs very well with only one buffer, and can achieve performance close to the store-and-forward case using a buffer size as small as four packets per node     

Performance Analysis of an Optical Switched Manhattan Street Network

Manhattan Street Networks (MSN) are bidimensional linear node sets arranged as the avenues and streets of Manhattan. Deflection routing is performed –either in the synchronous or in the asynchronous mode–by conveying incoming packets towards one of the two outputs. The simulation and analysis of all-optical MS networks is the central target of this paper. In order to avoid using complex electronics and/or optical domain buffers, the deflection routing and the asynchronism are taken into account in the analysis. The obtained results are compared and discussed with respect to some previously described analytic methodologies.     

移动自组网中基于部分网络编码的机会主义路由

完全网络编码可用以解决机会主义路由中空间重用及重复报文问题,但增大了报文平均延迟,且报文数据流表现出突发性特征,不利于目标节点解码.本文针对移动自组网提出基于部分网络编码的机会主义路由OR-PNC,采用任意长度部分网络编码方式对报文编码.实验表明OR-PNC可有效降低报文平均延迟达26%,目标节点应用层原始报文到达流更均衡.