光分组交换网

本文介绍了全光分组交换网的国内外研究状况，讨论了光分组交换节点的功能和结构及其实现光分组交换网的关键技术，对光分组交换网的研究具有重要的参考价值。     

光分组交换技术的研究

光分组交换技术的引入，改善了带宽的利用率和网络的灵活性，延伸了光的透明性。在光分组交换层中光分组的产生、同步、缓存、再生，分组头重写及分光组之间挑功率的均衡成为实现光分组产换的基本技术，而多波长方案并不是光分组交换的唯一模式，光时分分组交换、光标签交换、波分及混合分组交换、多协议标签交换、光突发分组交换等交换方式的出现必将对未来的通信网产生重要的影响。     

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(OBS)网络TCP性能改善

介绍光突发的基本原理及影响OBS网络TCP性能的一些因素，并针对TCP性能的改善的两种方法进行了详细说明，提出了一种改进策略。     

异步光分组交换网的流量建模

研究了异步光分组交换网的流量特性，提出了网络流量的解析模型和近似模型。研究表明，在采用计时门限光分组组装算法的情况下，如输入IP流具有短程相关特性(ShortRangeDependent)，则光分组的到达间隔时间呈负指数分布，光分组的长度趋于高斯分布。     

光突发交换网关键技术及发展

本主要介绍了光突发交换网的关键技术，并在同光波长交换网络和光分组交换网络相比较的基础上，对光突发交换的发展前景做了乐观的估计。     

基于可变长光突发数据分组的OBS网络性能分析

光突发交换(OBS)网络是迈向全光分组交换网络的典型代表.文章主要研究了基于可变长光突发数据分组的OBS网络性能,给出并分析了不同负荷量大小的情况下网络中的平均突发数据分组数量等参数.在设定网络速率为10和40 Gbit/s的情况下,给出了网络平均时延、突发数据分组负荷量及突发数据分组长度之间的关系.所得结果可作为对OBS网络理论研究的一种补充.     

光突发交换网络中TCP Reno 的性能分析

该文在分析光突发交换(OBS)网络对TCP性能影响的基础上,研究了单个突发所包含的属于同一TCP/ IP连接的分组数对TCP Reno吞吐量性能的影响,得到了一个吞吐量与突发丢失率、单个突发所包含分组数以及往返时延(RTT)的闭合表达式;并通过仿真验证了分析的正确性;分析和仿真结果表明,在接入链路带宽较大时,突发所包含的分组数存在一个最佳值,使TCP吞吐量达到最大。     

光分组交换网的新技术

首先概述通信网的发展进程。接着介绍全光的分组交换网。再说明其相关的光信号处理和光波长转换技术。最后简单介绍同步光时分多路应用。     

光分组交换网中的一种新模型

目前常用的网络理论模型如曼哈顿网络、洗牌网等均不能适应光分组网络研究的需要.文章提出了一种新的光网络模型———自相似环流网状网.该模型特别适合于光分组网络的研究.文章还研究了该模型的许多特性.     

Optical signal processing for optical packet switching networks

Optical packet switching promises to bring the flexibility and efficiency of the Internet to transparent optical networking with bit rates extending beyond that currently available with electronic router technologies. New optical signal processing techniques have been demonstrated that enable routing at bit rates from 10 Gb/s to beyond 40 Gb/s. We review these signal processing techniques and how all-optical-wavelength converter technology can be used to implement packet switching functions. Specific approaches that utilize-ultra-fast all-optical nonlinear fiber wavelength converters and monolithically integrated optical wavelength converters are discussed and research results presented.     

光分组交换技术在未来通信网中的应用

随着带宽需求的日益增长,电信工业不得不把重心从传统的电话业务转向IP数据业务。在这种情形下,SDH/SONET的作用大大地减小了,而OTN（光传输网）将为IP数据业务提供一个全球的基础传输设施。采用了DWDM和OXC的光网络为传输IP业务提供了许多新的机会与挑战。该网络不仅可以在网络之间快速自动建立和拆除路由,而且还可以在路由上支持多种用户信号。因此,今天的光网络发展计划关键在于核心网络可以提供一个以快速OXC和适当的管理控制机制为基础的可重构的光传输层。在不久的将来,光传输网将能够支持大量的高容量的光信道,这…     

An in-band signaling protocol for optical packet switching networks

Advances in optical networking reveal that all optical networks offering a multigigabit rate per wavelength will soon become economical as the underlying backbone in wide-area networks, in which the optical switch plays a central role. One of the central issues is the design of efficient signaling protocols which can support diversified traffic types, in particular the bursty IP traffic. This paper introduces a novel signaling protocol called the sampling probe algorithm (or SPA) to be used in a class of optical packet switching systems based on wavelength division multiplexing (WDM). The proposed scheme takes a drastically different approach from all existing signaling protocols. The salient features are 1) the pretransmission coordination is using an in-band signaling protocol, and thus does not require separate control channel(s) for transmission coordination; 2) the protocol is based on a reservation (connection) scheme which is capable of supporting multimedia traffic; 3) a gated service is adopted in which each successful reservation allows multiple packets (train of packets) to be transmitted, which can significantly reduce the per packet overhead; 4) the scheduling algorithm is adaptive by allowing flexible assignment of bandwidth on-demand; 5) the channel status gathering is done in a distributed fashion, and uses a passive listening mechanism, which itself does not interfere with packet transmissions. The results demonstrate that the proposed in-band signaling protocol can achieve high throughput and stability under heavy traffic condition.     

An effective buffering architecture for optical packet switching networks

A novel optical buffering architecture for Optical Packet Switching (OPS) networks is proposed in this article. The architecture which adopts a fiber-sharing mechanism aims at solving the problem of using a large number of fiber delay lines that are used to solve resource contention in the core node in OPS networks. The new architecture employs fewer fiber delay lines compared to other simple architectures, but can achieve the same performance. Simulation results and analysis show that the new architecture can decrease packet loss probability effectively and achieve reasonable performance in average packet delay.

Impact of cumulative polarization-dependent gain on SOA-based optical packet switching networks

The physical layer scalability of multistage interconnection networks is determined by the maximum number of internal switching nodes that packets can traverse error-free. We show that for nodes based on commercial semiconductor optical amplifier switches with polarization-dependent gain of less than 0.35 dB, the maximum number of cascaded nodes could vary by as much as 20 nodes, depending both on the packet wavelength and its state of polarization. We explain such a dramatic effect by optical signal-to-noise ratio degradation due to accumulated amplified spontaneous emission noise with the number of nodes.     

光突发交换网络中冲突性能分析

光突发交换(OBS)被认为是下一代光纤通信网络的典型代表.文章研究了在OBS核心节点中突发数据包由于竞争相同的输出数据信道而发生的冲突问题,对冲突时的网络性能进行了分析,得出了在不同网络负荷情况下的包丢失率情况,研究结果对OBS网络的实际建设有一定的理论指导意义.     

折射路由法在光分组交换网络中的运用

就OTDM(光时分复用)光分组交换网络的交换节点功能和关键技术进行了分析和探讨。对无缓冲折射路由法在街区网络上的应用和路由算法进行了深入研究，并根据概率分析模型，求得在稳定状态下吞吐量和平均时延的计算公式，最后与有缓冲区的存储转发网络的性能进行了比较。     

Architectures and performance of optical packet switching nodes for IP networks

As new bandwidth-hungry Internet protocol (IP) services are demanding more and more capacity, transport networks are evolving to provide a reconfigurable optical layer in order to allow fast dynamic allocation of wavelength-division-multiplexing (WDM) channels. To achieve this goal, optical packet-switched systems seem to be strong candidates as they allow a high degree of statistical resource sharing, which leads to an efficient bandwidth utilization. In this paper, we propose an architecture for optical packet-switched transport networks, together with an innovative switching node structure based on the concept of per-packet wavelength routing. The traffic performance of such node when loaded by a typical IP traffic is evaluated through computer simulation; packet loss probability and average delay performance are shown for various load conditions.