光突发交换资源预留过程分析和排队模型

光突发交换集合了光电路交换和光分组交换的优点。资源预留过程对OBS至关重要。本文讨论分析了OBS资派预留的重要参数以及它们对资源预留性能的影响，并用排队论的模型详细研究了资源预留过程。     

光突发交换中波长预留协议及其比较

光突发交换(OBS)方案中，源节点突发数据一旦产生，沿源节点到目的节点之间就要有专门的波长预留。为此介绍了几种波长常见的波长预留协议。并从阻塞率、平均建立时间、平均控制分组数的角度来比较几种协议的性能。     

基于模拟光突发交换结构的星载光网络资源预留机制研究

为了适应可实现性强、稳健性高的卫星光交换网络,选择模拟偏置时间光突发交换(E-OBS)作为转发卫星的激光通信架构,并结合现有的地面光交换资源预留方法,提出了一种偏置时间固定的资源预留机制。通过流量估计把突发数据按照目的地址和服务质量(Qo S)区分为单个突发和突发流,按照分类对卫星光网络资源进行了成功预留,并建立了平均端-端时延、吞吐量、链路利用率、丢包率数学分析模型。理论分析与仿真证明,该资源预留方法通过突发流机制降低了光交换矩阵的重置时间和交换时延,通过E-OBS架构降低了核心节点控制复杂度和对边缘节点的缓存需求,提高了网络吞吐量,适用于星载光交换网络。     

下一代光互联网交换技术——光突发交换的关键技术

本文阐述了光突发交换技术的基本原理，并对OBS中资源预留协议、流量等级、资源竞争、预约机制和偏置时间确定等关键技术进行了介绍。简要指出了OBS网面临的瓶颈以及未来主要研究方向。     

光突发交换与下一代互联网

光突发交换与交换粒度介于光电路交换（即波长交换）和光分组交换之间的一种光交换模式，因为它克服了光电路交换和光分组交换的缺点，具有很大的技术优势，很有可能成为下一代互联网骨干网络的核心技术，真正实现光子互联网。本介绍光突发交换技术的基本原理，讨论了光突发交换的协议，突发封装和在IP骨干网中的应用等问题，并指出在这项技术得到应用之前需要解决的诸多课题。     

光突发交换技术

介绍了一种很有发展潜力的新交换模式－－光突发交换。对其基本概念、交换原理、网络结构、节点结构进行了简明的阐述,通过与另外两种典型交换模式－波长路由与光分组交换的比较,总结了光突发交换的优势,并指出了光突发交换尚待解决的问题。     

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.     

基于下一代光互联网的光突发交换技术研究

文章首先讨论了与光突发交换（OBS）相关的一些问题。接着讨论了OBS如何应用于下一代光互联网中，特别是偏置时间和延迟预留协议有助于避免使用光缓存，能在波分复用（WDM）层支持服务质量（QoS)服务。     

光突发交换中的冲突解决协议

文章介绍了适合于在当前技术条件下的新交换技术-光突发交换，并对光突发交换中的各种冲突解决协议进行了阐述和对比．     

光突发交换关键技术

因特网流量呈指数增长，到2005年时，有望达到话音流量的10倍。这种形势，促使研究们加快对波分复用(WDM)传输和光交换技术深入研究，以便适应因特网流量的爆炸式增长、业务的多样性和业务突发性。考虑到IP网络的发展趋势和光技术的先进性，下一代因特网必然是以WDM网络为基础、以因特网业务流量为主的优化IP光网络(即IP over DWDM)。     

Soft‐State Bandwidth Reservation Mechanism for Slotted Optical Burst Switching Networks

This paper proposes a novel transport network architecture for the next generation network (NGN) based on the optical burst switching technology. The proposed architecture aims to provide efficient delivery of various types of network traffic by satisfying their quality‐of‐service constraints. To this end, we have developed a soft‐state bandwidth reservation mechanism, which enables NGN transport nodes to dynamically reserve bandwidth needed for active data burst flows. The performance of the proposed mechanism is evaluated by means of numerical analysis and NS2 simulation. Our results show that the packet delay is kept within the constraint for each traffic flow and the burst loss rate is remarkably improved.     

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.     

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.     

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.     

Fair Bandwidth Allocation in Optical Burst Switching Networks

Optical burst switching (OBS) is a promising switching technology for next-generation Internet backbone networks. One of the design challenges is how to provide fair bandwidth allocation in OBS networks; the schemes proposed for general store-and-forward IP switching networks can not be used because of the non-buffering and un-fully utilized bandwidth characteristics of OBS networks. We propose a rate fairness preemption (RFP) scheme to achieve approximately weighted max-min fair bandwidth allocation in OBS networks. We present an analysis of the burst loss probability in RFP-based OBS networks. The analysis and simulation results show that the RFP scheme provides fair bandwidth allocation in OBS networks.      

光突发交换网络中一种基于负载平衡的路由机制

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.     

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…