光突发交换研究综述与应用展望

介绍了OBS概念与网络结构,总结了国内外研究OBS的热点问题,给出实现OBS的关键技术与方法。通过讨论OBS在Grid网络环境中的潜在应用,给出了相应的模型结构。最后对光突发交换的发展前景做了初步展望。     

业务驱动的光子网格关键技术研究

通过对光子网格资源管理新机制、光子网格中间件和光子网格用户网络接口等关键技术的研究，建立业务驱动的光资源动态调度方法，给出大块数据传输及视频点播（VOD）服务在可控光路与基于OBS的网格（Grid over OBS）模式下的业务应用模式。理论与实验证明业务驱动的光子网格关键技术的实现，使得光子网格能很好地为密集数据业务服务。     

全光网络中一种基于完全图的分组调度算法

在无缓存的全光OBS网络中由于相互竞争而被丢弃的数据突发是造成其高丢包率的主要原因,而分组调度策略可以从整体上改善OBS网络的这种缺点。本文建立了一种改进的分组调度映射模型,并提出了一种基于完全图的分组调度算法,该算法相对简单且容易实现,能够较好地解决OBS网络中由于数据突发的无序竞争所致的丢包问题,从而进一步提高网络的服务质量及其信道利用率。     

一种改进的OBS/GMPLS网络通路建立机制

OBS/GMPLS网络可以很好的实现传统OBS网络不具备的自动发现、流量工程、良好的保护恢复等功能。基于重叠模型的OBS/GMPLS网络架构,针对GMPLS信令执行资源预留时存在的链路资源部分闲置状态,提出了两种改进策略,包括宿结点的上游结点提前回送Resv消息和对BHP消息设置偏置时间以控制BHP的发送。理论分析表明改进方案可以缩短链路的建立时间,提高资源利用率。     

一种非循环的光突发交换网络偏射路由算法

文章提出了一种非循环的应用于光突发交换(OBS)网络的偏射路由算法．它基于各网络节点的路径度和平均跳转数来确定偏射路径．通过建立OBS网络仿真模型。从数据突发的丢失率、平均跳转次数和端到端延时等方面来对其进行评价．仿真结果表明，该算法能确定有效的非循环偏射路径，为OBS网络提供了公平的网络资源利用．     

光突发交换网络管理的研究与实现

讨论了OBS网络管理的需求和网管信令的传输方式,并且提出了基于SNMP的OBS网络管理体系结构及相关网管软件的设计方案。     

PON与OBS网络互连结构的研究

光突发交换(OBS)网络的城域网应用需要解决与接入网的互连问题。针对基于集成节点的PON与OBS网络互连方案,研究了集成节点的功能与组成结构,分析了模块之间的信息交互,给出了集成节点结构的一种设计方案,并简单讨论了基于这一方案的汇聚机制和动态带宽分配算法。     

光突发交换网络中的闭环竞争解析

为改善光突发交换网络(OBS)的性能,深入探讨了光突发交换网络中的闭环竞争解析,提出了OBS网络中的主动资源预留方案OBS—RED和显式竞争通知方案OBS—ECN。OBS—RED采用随机早期丢弃策略,即根据数据信道拥塞情况,随机早期地丢弃控制分组。OBS—ECN的实现需要OBS—RED的支持。在OBS—ECN中,不是随机丢弃控制分组,而是将这一信息显式地通知边缘节点,边缘节点再作相应的处理。OBS—RED与OBS—ECN的应用,有利于提高网络吞吐量和链路带宽资源利用率,大大减少数据突发的阻塞概率。     

基于GMPLS的光突发交换网络的研究

文章基于通用多协议标签交换(GMPLS)的光突发交换(OBS)网络的体系结构,研究了如何将GMPLS引入OBS,并使两者能够高效协调地工作.重点讨论了GMPLS与OBS技术相结合的网络(GMPLS-based OBS)的各种关键技术和解决机制.特别在处理突发数据包(BDP)冲突竞争机制上提出了新的方法.最后,指出了GMPLS-based OBS进一步研究的方向.     

TCP over OBS边缘节点重传机制的研究

使用传输控制协议(TCP)的拥塞控制机制在传统互联网技术中是解决问题的很好方法.然而在面对新型的光网络技术OBS网络,简单地采用TCP技术因受到OBS自身特性的影响,性能表现不佳,吞吐量低下.为此,通过对OBS技术和TCP拥塞控制机制深入的研究,提出一种基于OBS边缘节点的ACK重传机制来提升TCP over OBS性能的方法,提高OBS网络吞吐量.     

Architectural approaches for the integration of the service plane and control plane in optical networks

This paper presents some instantiations of novel application-aware network architectures for emerging IT services and future Internet applications. It proposes and analyses network architectures where the Control and Service Planes are closely and seamlessly interacting with the applications. One instantiation, the Grid-GMPLS (G²MPLS, as defined by the Phosphorus project) is presented, which implements the Network Control Plane (NCP) architecture for the support of Grid Network Services (GNS). The GNS allows the provisioning of network and HPC/Grid resources in a single-step through a set of seamlessly integrated procedures. In a second example of instantiation, a quite popular application in signalling, i.e. the Session Initiation Protocol (SIP), is integrated with the Optical Burst Switched (OBS) network technology. The SIP-enabled OBS network can be used to manage application sessions and provide network and IT services according to application requirements. This paper investigates the requirements that these new integrated architectures impose on supporting network Control and Service Planes, and technologies, and discusses their possible implementations.     

Hybrid switching and p-routing for optical burst switching networks

One promising switching technology for wavelength-division multiplexing optical networks is optical burst switching (OBS). However, there are major deficiencies of OBS. (1) The delay offset between a control message and its corresponding data burst is based on the diameter of a network. This affects network efficiency, quality-of-service, and network scalability.( 2) OBS adopts one-way resource reservation scheme, which causes frequent burst collision and, thus, burst loss. We address the above two important issues in OBS. In particular, we study how to improve the performance of delay and loss in OBS. To reduce the end-to-end delay, we propose a hybrid switching scheme. The hybrid switching is a combination of lightpath switching and OBS switching. A virtual topology design algorithm based on simulated annealing to minimize the longest shortest path through the virtual topology is presented. To minimize burst collision and loss, we propose a new routing algorithm, namely, p-routing, for OBS network. The p-routing is based on the wavelength available probability. A path that has higher available probability is less likely to drop bursts due to collision. The probability-based p-routing can reduce the volatility, randomness, and uncertainty of one-way resource reservation. Our studies show that hybrid switching and p-routing are complementary and both can dramatically improve the performance of OBS networks.     

采用光突发交换技术组建动态光虚拟专用网

光突发交换是光路交换和光分组交换的一个有效折衷方案，避免了两者的缺点，能很好的适应未来业务量爆炸式增长及业务的多样性和多变性的要求。光虚拟专用网业务使得企业能够在公网内部灵活地组建自己的网络拓扑，避免支出建设专用网络的学生费用，同时使得运营商优化带宽的利用率，通过较少的投资获得更多的商业机会从而增加收入，把OBS技术应用于OVPN网络将使其具有更大的灵活性，安全性和可扩展性。这里介绍了OBS原理和功能，阐述了OVPN体系结构及参考模型，对采用OBS技术组建动态OVPN进行了探讨性研究。     

基于集成节点的PON与OBS网络互连技术研究

无源光网络(PON)与光突发交换(OBS)网的互连是光分组传送网络发展的必然.文章分析了PON与OBS网互连存在的主要问题及已有的解决方案,提出一种聚合PON与OBS边缘节点功能的集成节点结构,研究基于集成节点的PON与0BS网络互连技术方案,提出基于业务流量的三级汇聚机制,分析结果表明三级汇聚机制可以保证业务等级,减少业务延时.     

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。     

基于对象存储的Lustre文件系统的研究

随着高性能计算网络集群系统的高速发展，传统的网络存储架构——网络附加存储NAS和存储区域网SAN已越来越不能够满足系统对存储性能的要求。针对SAN和NAS的不足，新一代的网络存储技术——基于对象存储OBS成为了研究的热点。重点论述了基于对象存储的架构和特点，并针对基于对象存储的Luster文件系统进行了初步测试，通过和传统的NFS文件系统对比，分析了对象存储文件系统在可扩展性、性能、易用性和安全性等方面的优越性能。     

TCP over optical burst-switched networks with controlled burst retransmission

For optical burst-switched (OBS) networks in which TCP is implemented at a higher layer, the loss of bursts can lead to serious degradation of TCP performance. Due to the bufferless nature of OBS, random burst losses may occur, even at low traffic loads. Consequently, these random burst losses may be mistakenly interpreted by the TCP layer as congestion in the network. The TCP sender will then trigger congestion control mechanisms, thereby reducing TCP throughput unnecessarily. In this paper, we introduce a controlled retransmission scheme in which the bursts lost due to contention in the OBS network are retransmitted at the OBS layer. The OBS retransmission scheme can reduce the burst loss probability in the OBS core network. Also, the OBS retransmission scheme can reduce the probability that the TCP layer falsely detects congestion, thereby improving the TCP throughput. We develop an analytical model for evaluating the burst loss probability in an OBS network that uses a retransmission scheme, and we also analyze TCP throughput when the OBS layer implements burst retransmission. We develop a simulation model to validate the analytical results. Simulation and analytical results show that an OBS layer with controlled burst retransmission provides up to two to three orders of magnitude improvement in TCP throughput over an OBS layer without burst retransmission. This significant improvement is primarily because the TCP layer triggers fewer time-outs when the OBS retransmission scheme is used.     

基于保护资源的混合光交换网络

提出一种基于保护资源的混合光交换方案P_HyLABS。该方案利用光电路交换(OCS)网络中的保护资源(波长信道),构建光突发交换(OBS)网络层,与OCS工作光路组成的OCS网络层一起,组成OCS/OBS混合交换网络。仿真结果表明,由于将OCS传送的电路交换的优势与OBS传送的统计复用能力进行了较好的结合,与单一的OCS网络和OBS网络相比,P_HyLABS混合交换在保证数据高效传输的同时,可应对呈高突发性的数据传送,在多失效的网络环境下也能部分恢复数据传送。     

Analysis of blocking probability in optical burst switched networks

In this article, we study the blocking probability in a wavelength division multiplexing (WDM) based asynchronous bufferless optical burst switched (OBS) network, equipped with a bank of wavelength converters. Our analysis encloses two wavelength reservation schemes JIT (just-in-time) and JET (just-enough-time), and two-class data rate. The contribution of our work includes: (i) derivation of an accurate model for blocking probability of lower priority bursts in case of a non-preempted model; (ii) provision of the analytical model for blocking probability calculation in the OBS network, which includes these variables: two signaling schemes, partial wavelength conversion, two-class data, traffic intensity, cross-connect speed, number of wavelengths in WDM fiber, number of fibers in the node, number of wavelength converters, and number of nodes in the path; (iii) simulation results, which show that partial wavelength conversion provide quite satisfactory quality of service. We compare performance in a single OBS node, under various sets of parameter values. The OBS network shows great flexibility in terms of used multiclass data, and there is no dependence on the used higher layer protocol.