基于定长光突发数据的OBS网络性能分析

光突发交换(OBS)技术是下一代全光分组交换技术的典型代表.本文主要研究并分析了基于固定长度光突发数据的OBS网络平均时延、突发数据数量等性能,给出了各参量随信道负荷量变化时的变化规律.     

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。     

OBS光网络技术及最新进展

光纤传输技术和光网络技术的发展使得光网络成为现代高速宽带网络的基础骨干网。光突发交换是一种介于光路交换和光分组交换之间的很有发展潜力的交换模式,它结合了两者的优势又克服了两者的缺点。重点阐述了光突发交换的概念和关键技术,并介绍了光突发交换目前的研究进展。     

OBS网络中的虚拟突发交换技术

针对由于网络复杂度提高,突发数据在预留时冲突可能性增大,导致OBS网络性能下降的情况,提出OBS网络中的虚拟突发交换技术和相应的实现技术。其汇聚机制是基于服务类别的虚拟汇聚,调度策略对应有两种：非抢占调度策略和抢占调度策略。利用虚拟突发交换技术有利于减少信道碎片,提高链路利用率,提供可靠的QOS保证。用OPNET系统仿真工具进行验证,结果表明：虚拟突发交换与OBS传统交换方式相比有较高网络链路的利用率,较少的控制分组和数据突发的丢包率,增加了整个网络的吞吐量。     

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。     

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.     

OBS网络数据信道调度算法性能比较与分析

光突发交换(0BS)网络中的数据信道调度算法是提高0BS网络性能的关键技术之一.首先介绍和分析了LAUC、LAUC-VF和0DBR基本原理和性能,结合国内外最新研究成果,介绍了四种支持QoS的数据信道调度算法,最后对其应用场合做出总结.     

光突发数据包整合技术的研究

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。介绍了控制分组结构。重点研究了光突发交换的关键技术—突发数据包整合技术的各种方法，指出突发数据包整合技术在很大程度上影响着光突发交换网的性能。     

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.     

光分组交换网的TCP性能研究

与传统光网络相比,光分组交换(OPS)网络具有高速、大吞吐量、低时延和能高效地承载IP业务等突出优点.而作为支撑下一代Internet发展的最有希望的骨干光网络,OPS网与传输控制协议/互联网协议(TCP/IP)的兼容性和支持度是一个值得深入研究的课题.文章以光突发交换(OBS)网为模型,对OPS网络中的TCP传输性能进行了研究.     

Performance analysis of OBS networks using the effective bandwidth method

This article provides a new scheme for the blocking probability evaluation for optical burst switching networks. While several previous articles used mainly links as servers, we consider switches as servers. In order to evaluate the blocking probability at switches, we use the effective bandwidth method. The method shows more accurate results and the accuracy of the method is proven by simulation and numerical analyses.     

Performance analysis of asynchronous best-effort traffic coexisting with TDM reservations in polymorphous OBS networks

The in-advance reservation of bandwidth capacity philosophy of Optical Burst Switching architectures via Burst-Control Packets brings high flexibility in the separation of network resources for services with different quality-of-service requirements. In this light, real-time applications can periodically be guaranteed a certain amount of bandwidth reservation for the transmission of traffic with Constant Bit Rate requirements (for instance IP television, VoIP, etc), whilst the remaining capacity may be used for transmission of best-effort traffic of the so-called elastic applications (e-mailing, web browsing, etc). The Polymorphous, Agile and Transparent Optical Networks (PATON) architecture (Qiao et al. IEEE Commu Mag 44(12):104–114 2006) proposes periodic reservation of time-slots over one or several wavelengths of an optical fibre, yet remaining gaps in between them for transmission of best-effort traffic. This work presents a novel analysis of the performance perceived by best-effort traffic which are given full access to optical switching only during a portion of the total time. The following analyses the non-blocking probability among best-effort data bursts that share such available gaps in between the periods of CBR traffic. An exact expression of the non-blocking probability is derived when a single wavelength is used for CBR traffic, along with a lower bound for the case when CBR traffic is transmitted using multiple wavelengths. These results can be of further interest in the optimal design of OBS architectures where the transmission of high-priority real-time traffic and best-effort data coexist over the same wavelength.

Performance comparison of OBS and SONET in metropolitan ring networks

This paper explores the feasibility of deploying optical burst switching (OBS) in metropolitan area networks (MANs) as an alternative to synchronous optical network (SONET), over wavelength-division multiplexing. We present a comparison between two OBS architectures (with centralized and distributed scheduling schemes), SONET, and next-generation SONET (NG-SONET), respectively. We quantify some of the performance metrics such as end-to-end delay and loss rate when supporting Ethernet traffic in metro ring networks. Our simulation results show that OBS offers significant performance improvement over SONET and NG-SONET. In general, the OBS architecture with distributed scheduling has a superior delay performance, whereas the OBS architecture with centralized scheduling has a better loss metric.     

OBS网络中突发重传和IP包重传的性能比较

文章分别分析了将基于优先级的突发重传和基于分段的IP包重传方式引入光突发交换(OBS)网络后的性能,并对这两个机制进行了分析比较.通过分析比较发现,采用基于优先级的突发重传可以有效地减少重传次数、所需缓存和重传延迟,提高网络吞吐量,是OBS网络中的一种理想的重传选择方案.     

光突发交换网络中突发模式发射机设计

分析了光突发交换(OBS)网络中突发模式光发射的关键技术,提出了采用外调制技术实现突发模式光发射机的设计方案.其核心部件是多量子阱电吸收调制器(MQW-EAM),并对其驱动电路和整体电路进行了仿真,论证了实现突发模式光发射机的调制方式及其主要技术指标.     

Performance analysis of limited-range wavelength conversion in an OBS switch

We compute analytically burst blocking probabilities in an OBS switch when limited-range wavelength conversion is employed. Two separate queueing models are proposed and analyzed approximately; one for the case where the degree of conversion d is 1 or 2, another for large values of d. The arrival process of bursts is assumed to be an IDLE-ON process. The accuracy of these queueing models was tested against simulation. We show numerically that in order to keep the burst blocking probability within an acceptable level, the utilization of each wavelength has to be low.     

OBS网络核心节点冲突性能分析

对光突发交换(OBS)核心节点中突发数据包的冲突问题进行了性能分析,比以往同类研究改进之处在于,不仅给出了包阻塞率情况,还给出了OBS系统数据通过能力以及系统被占用均值等性能,结果对0BS冲突领域的研究进行了有益的补充和完善.     

配备光缓存的OBS核心路由器性能分析

光突发交换(Optical Burst Switching,OBS)网络是下一代IP over WDM全光网络的发展趋势.文章主要研究并分析了OBS网络中配备有光缓存的核心路由器性能,给出了突发数据分组阻塞率、输出端口占用率、排队时延等性能参数.所得结果对0BS网络理论研究进行了一定的补充.     

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。