光突发交换技术

光突发换是近几年出现的一种光交换技术 ,它交换的单元粒度介于电路交换和分组交换之间 ,比电路交换灵活 ,带宽利用率高 ,又比光分组交换易于实现 ;全面介绍了这种交换技术 ,并对它与电路交换和光分组交换性能进行了比较。另外 ,还对光突发交换的关键技术进行了讨论 ,结合下一代互联网的技术趋势 ,对光突发交换的前景进行了评价。     

光突发交换技术

文章介绍了光子交换的发展情况,着重介绍了光突发交换的原理、网络和节点的结构、突发封装技术、协议以及发展方向.     

利用GMPLS实现光突发交换

DWDM技术虽然可以实现较大的传输容量，但是在对信息进行处理的过程中，却存在着电子瓶颈，传统网络仍然需要在交换节点处对数据进行电的交换处理，从而降低了网络的交换处理速度。为了实现在光网络上直接传送数据业务，人们提出三种IP over DWDM网络方案：波长路由交换光网络、突发交换光网络和分组交换光网络。     

基于标签的光突发交换网络

先进的OBS(optical burst switching)技术和MPLS的强大控制能力结合产生了一种灵活紧凑的IP/DWDM集成模型LOBS.(labeled optical burst switching).它充分发挥了电子处理的高智能和光子交换的大容量优势,是未来数据网络的理想光交换方案.文中从OBS技术的优越性开始,分析了LOBS实现的网络结构和控制协议,探讨了LOBS流量工程和网络生存性.     

光通信网对数据信息的Burst交换

说明通信网交换方式从电路交换至分组交换和Burst交换的演变以适应全光通信网的发展趋势。解释了通信网利用Burst交换所需的网络边缘设备和核心结点设备。     

Congestion-Controlled Optical Burst Switching Network With Connection Guarantee: Design and Demonstration

A congestion-controlled optical burst switching network that offers connection guarantees was designed to handle bursts as short as 100 ms with switching within 10 ms in networks less than 200 km long. Its optical burst switching (OBS) is based on circuit switching, and transport is by optical burst paths. Five metrics are proposed for evaluating OBS network performance. The application area to be laid and the data application were determined in accordance with the design target. Given a reasonable burst block probability requirement, design criteria are developed on the basis of wavelength switching and conversion implementation. OBS network performance is tested in field trials on the Japan Gigabit Network II testbed. Fast congestion control through the use of precalculated detour routes is demonstrated.      

光突发交换网络中的突发分组组装策略

光突发交换(OBS)技术集成光电路交换和光分组交换的优势,能满足现有大容量、高速率的多媒体信息交换与传输,将成为下一代光IP骨干网的核心技术。本文详细论述了OBS网络中的关键技术———突发分组的组装技术的各种策略与实现方式,指出具有良好QoS保证又可降低可操控性的突发组装策略将成为最佳选择。     

光突发交换网络边缘节点突发装配方案

介绍了光突发交换网络边缘节点突发装配的关键技术，详细论述了IP分组到达入口边缘节点后进入缓存的不同排队策略，重点研究了目前已经提出的各种突发装配策略，并对不同的突发装配策略进行分类比较。     

A Data Burst Assembly Algorithm in Optical Burst Switching Networks

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.     

Performance Evaluation of Slotted Optical Burst Switching Systems With Quality of Service Differentiation

Slotted optical burst switching (SOBS) has recently caught the attention of the optical networking community due to performance gains achievable with synchronous infrastructures. In this paper, we study the loss probabilities in a slotted optical burst switching node fed with Poisson burst traffic where the fixed burst size is an integer multiple of the slot length. We develop a discrete-time Markov chain (DTMC) based framework to obtain the loss probabilities in systems with and without quality of service (QoS) differentiation. In particular, we focus on analytical modeling of priority scheduling and offset-based QoS differentiation mechanisms for SOBS networks. The latter problem suffers from the curse of dimensionality which we address by a discrete phase type distribution approximation for the discrete Poisson distribution leading to an accurate approximation for the loss probabilities. A hybrid QoS mechanism which jointly utilizes offset-based differentiation together with priority scheduling is also analyzed.      

光突发交换网络中服务质量保证机制的研究

如何在光突发交换(OBS)网络中为承载的业务提供服务质量(QoS)保证,已经成为当前OBS领域的一个研究热点.从算法思想、QoS保证性能等方面,对当前几种主要的服务质量保证机制进行了研究:基于偏置时间的QoS机制、分段型QoS机制、比例型QoS机制、抢占式QoS机制、IP DiffServ over OBS的QoS机制以及基于数据信道分组的QoS机制.探讨了在设计一个有效的QoS保证机制时应考虑的因素以及今后的研究方向.     

光突发交换网络中的传输控制协议性能

光突发交换(OBS)是IP over WDM核心网络采用的交换技术。在OBS网络中,送往同一边缘节点的IP分组汇聚成传输和交换的基本单元———数据突发(DB),DB丢弃会导致大量IP分组丢失,显著影响传输层的性能。文中分析OBS网络的参数对传输控制协议(TCP)吞吐量和时延的影响。仿真结果表明,DB丢包率越高,TCP性能越差。在低丢包率情况下,随着DB长度的增加,TCP吞吐量和端到端时延明显增加,高丢包率情况下则不明显;随着汇聚周期的增加,TCP吞吐量逐渐下降,端到端时延逐渐增加。     

光突发交换网络基于优先级与突发包分割的光缓存方法

为了保证光突发交换(OBS)网络中不同优先级业务的服务质量(Qos)和有效地降低突发包的丢失率,提出了一种基于优先级与突发包分割的光缓存方法.该方法通过在输出数据信道上设置光纤延迟线组来缓存被分割的冲突突发包.当冲突发生时,基于突发包的优先级进行"竞争突发包头部分割或者原突发包尾部分割,,处理;无冲突部分进行交换或者直...     

Burst Assembly Schemes and Performance Evaluation in Optical Burst Switching Networks

1　Introduction　TheopticalInternethasbeenemergedasanefficientsolutionforsupportingever increasingInternettrafficbytakingadvantageofpotentiallyhugebandwidthofWavelength DivisionMultiplex (WDM )opticalnet works.Tomeettheincreasingbandwidthdemandsandreducecosts ,severalopticalnetwork paradigmshavebeenunderintensiveresearch .Ofalltheseparadigms,OpticalCircuitSwitching (OCS[1～ 3] )isrelativelyeasytoimplementbutlacksflexibilitytocopewiththefluc tuatingtrafficandthechanginglinkstate ,andrequi…     

基于光突发交换的下一代光互联网技术

给出了基于光突发交换的下一代光互联网技术的体系结构,然后从光突发数据格式、光突发的装配、光突发交换节点与网络结构、资源预留协议,以及数据信道调度算法等方面讨论了其核心技术问题.最后,简要地指出了下一代光互联网技术的未来研究方向和主要研究内容.     

Comparative Account of Bandwidth Efficiency in Optical Burst Switching and Optical Circuit Switching Networks

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.     

Burstification Queue Management in Optical Burst Switching Networks

Among the various issues lying in optical burst switching (OBS) networks, burstification, i.e., assembling multiple IP packets into bursts, is an important one. Between the two important aspects related to burst assembly, the burst assembly algorithm aspect has been extensively studied in the literature. However, as far as we know, there is no research about the burstification queue management (BQM) aspect, which refers to how many burstification queues (BQ) we should set at each OBS edge node and how to manage these BQs. Suppose there are G destinations (egress edge nodes) and the OBS network provides S different quality of service (QoS) classes. Traditionally, it is simply regarded that each ingress edge node needs G· S queues to sort incoming packets, one for each possible destination and QoS class. For simplicity, we call this policy the static dedicate BQM (SDB) policy. The SDB policy, though simple, lacks scalability since we have to add S BQs at each OBS edge node if an extra OBS edge node is added to the OBS network. To solve this problem, we propose in this paper two BQM policies: quasi-static BQM (QSB) policy and dynamic BQM (DB) policy. For the QSB policy, we derive the packet loss probability due to lacking BQs based on a Markov chain, from which we can work out the employed number of BQs for a given packet loss probability. Based on these results, the scalability of the QSB policy is also studied. With the DB policy, we not only can dynamically assign BQs for incoming packets, but also can dynamically allocate buffer capacity for each BQ by using a least-mean-square (LMS)-based linear prediction filter. The performance of the DB policy is investigated by analysis and extensive simulations. We also compared the performance of the QSB policy and the DB policy. Results from analysis and simulation demonstrate that the DB policy is the best.     

LOBS技术研究

光突发交换技术(OBS)是一种新出现的光交换技术,它综合了光波长路由和光分组交换的优点。本文的LOBS又将MPLS 和OBS这两大技术结合在一起,利用MPLS强大的控制能力为OBS网络在QoS、流量工程和网络恢复等方面提供良好的支持。文章根据LOBS的基本原理,提出并详细阐述了它的网络构成和工作机制,最后指出了LOBS网络在流量工程和网络生存性方面相对其他光网络的优越性。     

光突发交换技术及其研究进展

随着全球范围内IP业务的迅猛增长,对传送网带宽和交换系统容量的需求正以前所未有的速度增加。目前,在光层利用DWDM技术,可以使一根光纤的可利用带宽达到10Tbit／s左右,可以满足较长时期内对传送网带宽的要求。然而,采用通常的电路交换技术(时分、空分及波长交换)的交换速率远低于这个数值。这样,两者的失配对交换技术的发展提出了新的要求。