基于OPS与OXC的标签交换光网络

先进的光分组交换(OPS)技术与多协议标签交换(MPLS)技术强大控制能力的结合,产生了一种灵活紧凑的IP/DWDM集成模型基于标签的光分组交换(LOPS)技术。它充分发挥了OPS的灵活性和光交叉连接(OXC)的大容量优势,是未来核心光交换网络的理想解决方案。文章从OPS节点结构开始,分析了LOPS的网络结构和功能模型,简述了MPLS的控制能力。     

空分交换型OPS节点技术

光分组交换(OPS:Optical Packet Switching)核心交换节点结构的设计直接影响着光分组交换网络的性能.文章以空分交换型OPS核心交换节点结构为研究对象,对光分组交换节点结构中的竞争解决技术进行深入探讨.此外,还总结归纳了5种空分交换型OPS节点结构,即输出缓存型、反馈缓存型、共享缓存型、混合缓存型和无缓存型.     

OPS光网络简介

光子器件技术的迅速发展使光分组交换网络的研究不断完善。文章讨论光分组交换(OPS)的关键技术,介绍具有较大发展潜力的异步光网络变长光分组交换技术。     

光传送网向光分组交换网演进的策略探讨

光分组交换(OPS)是分组交换技术向光层的渗透和延伸,OPS网是未来光网络中承栽话音和数据等多种业务的理想平台.受IP业务的拉动以及目前不断发展的光交换技术的推动,OPS网络必将有着非常广阔的应用前景.文章描述了OPS传送网的分层结构以及网络组成结构,给出了近期、中期和远期3个发展阶段OPS传送网的分层参考模型,基于该参考模型,探讨了现有光传送网在3个发展阶段向OPS传送网演进的策略.     

基于标签的光分组交换网络

先进的光分组交换（OPS）技术和多协议标签交换（MPLS）的强大控制能力的结合产生了一种灵活紧凑的IP/DWDM集成模型LOPS。它充分发挥了OPS的灵活性和OXC大容量优势,是未来核心光交换网络的理想解决方案。从OPS节点结构开始,分析了LOPS的网络结构和功能模型,简述了MPLS的控制能力。     

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.     

光分组交换网络中的光缓存技术研究

论述了全光缓存技术在光分组交换(OPS)网络中的应用,以及光缓存器在分组交换节点的各种配置结构,实现全光缓存的关键技术等。最后对全光缓存器的发展方向作了展望。     

基于光标签的光分组交换系统研究

光码分复用(OCDM)系统在光域对各路信号进行光编/解码,对用户数据进行全光信号处理,但是用户数目受到光标签数量的限制.光分组交换技术具有高速率、对数据速率和格式透明等优点,更能适应快速变化的网络环境,但存在光标签的提取、更新和竞争的难题.介绍了一种新型的基于WDM(波分复用)和OCDM的光分组交换系统,结合了光码分多址(OCDMA)技术和光分组交换(OPS)技术的优点,既扩展了系统用户容量又避免了对标签进行电域的处理,实现了数据的全光交换.     

光分组交换网络结构

光分组交换技术日益成为世界各国研究的重点，光交换的结构设计是光分组交换技术的关键。文中详细介绍了目前正在研究的空间光开关、广播选择和波长路由三种光分组交换结构。随着光网络、光器件和光系统技术的发展，光分组交换必会走向实用化。     

基于OPS技术的超高速光孤子通信实现方案

通过对光分组交换(OPS)技术的讨论,实现了多交换节点的超高速光孤子通信传输方案.在详细阐述光孤子通信系统中光分组形式和OPS节点结构的基础上,进一步分析了传输方案实现的可行性,最后对该技术的优劣进行分析.指出,基于OPS技术的光孤子通信是实现未来全光网的首选.     

Optical packet switching in core networks: between vision andreality

The research on optical packet switching (OPS) has witnessed considerable progress in the 1990s. We examine the future potential of OPS in the core network by discussing this switching approach and the current status of a number of its enabling technologies. Many of these technologies are still in the stage of research and experimentation. We see that optical packet switching may be deployed in the long-term future subject to satisfaction of three main conditions/developments. First, additional technological developments have to take place to overcome remaining implementation challenges while making OPS cost-effective to deploy. Second, a rational migration scenario of the network toward gradual deployment of packet-based optical switching approaches should exist. Finally, carriers have to become more interested in packet-based optical switching solutions     

On the design of asynchronous optical packet switch architectures with shared delay lines and converters

Optical packet switching (OPS) is a promising technology to enable next-generation high-speed IP networks. A major issue in OPS is packet contention that occurs when two or more packets attempt to access the same output fiber. In such a case, packets may be dropped, leading to degraded overall switching performance. Several contention resolution techniques have been investigated in the literature including the use of fiber delay lines (FDLs), wavelength converters (WCs), and deflection routing. These solution typically induce extra complexity to the switch design. Accordingly, a key design objective for OPS is to reduce packet loss without increasing switching complexity and delay. In this paper, we investigate the performance of contention resolution in asynchronous OPS architectures with shared FDLs and WCs in terms of packet loss and average switching delay. In particular, an enhanced FDL-based and a novel Hybrid architecture with shared FLDs and WCs are proposed, and their packet scheduling algorithms are presented and evaluated. Extensive simulation studies show that the performance of proposed FDL-based architecture outperforms typical OPS architectures reported in the literature. In addition, it shown that, for the same packet loss ratio, the proposed hybrid architecture can achieve up to 30% reduction in the total number of ports and around 80% reduction in the overall length of fiber as compared to the FDL-based architectures.     

光突发交换中的路由技术

光突发交换是面向下一代因特网的光交换模式,是光电路交换和光分组交换的有效折衷方案,避免了各自的缺点.它使用的带宽粒度介于光电路交换和光分组交换之间,比光电路交换灵活,带宽利用率高,比光分组交换易于实现,是很有发展前途的光交换技术.路由技术在光突发交换中起重要作用,在很大程度上影响着光突发交换网络的性能.本文首先介绍了光突发交换技术的原理,然后分析了光突发交换技术的现状及存在的问题,最后探讨了光突发交换中的路由技术及其发展.     

Novel virtual OCS in OPS data center networks

This paper considers a novel virtual optical circuit switching (VOCS) scheme for data center networks where short flows are transmitted via optical packet switching (OPS), while long flows with reliability requirement are transmitted via VOCS. VOCS preserves the advantage of optical circuit switching (OCS) for reliable communication, while it overcomes the disadvantage of OCS in terms of low link utilization. In the VOCS/OPS scheme, idle periods of the virtual circuits can be used by OPS, which thus enhances the overall performance. Simulations on a six-dimensional torus topology data center network with 4096 (=4\(^6\)) nodes are conducted for the performance evaluation. We have observed that, compared to OCS, VOCS has much less adverse impact on the performance of OPS. Furthermore, quite a large number (i.e., 2048) of virtual circuits can be set up with little affect on the OPS performance.     

On the performance of different node configurations in multi-fiber optical packet-switched networks

With the development of optical packet-switching (OPS) technologies, multi-fiber OPS networks will play an important role in the future data transmissions. In such networks, instead of constructing some extremely expensive node configurations with strictly non-blocking switching function, a more practical solution is multi-board switches that contain a number of small-sized switching boards. In this article, we have evaluated the performance of several different multi-board switches, based on the following two main objectives: (i) better understanding the effects of different connection schemes between switching boards and optical buffers and (ii) investigating possible schemes for achieving comparable performance to that of the ideal, strictly non-blocking switches. Extensive simulation results have shown that unlike circuit-switched net- works, multi-board OPS cannot easily perform comparably to the strictly non-blocking switch by having slightly more fibers per link. Also, such a problem can be tackled by several different approaches. The most efficient one is to equip the switch with more buffers rather than to increase the switching-board size or to enhance the buffer sharing between different switching boards.     

Demonstration of bufferless optical packet switch with recursive stages of parametric wavelength converter

We demonstrate in an experiment an optical packet switching (OPS) using recursive parametric wavelength converters (PWCs) which uses the combination of two or more PWCs for wavelength conversions. The PWCs, which are based on four-wave mixing in highly nonlinear fibers, are possible for multiple wavelength conversion, allowing a share-per-node switching scheme, and thus significantly reducing the number of wavelength converters. Detailed demonstration of a developed OPS prototype using the joint of two PWCs indicates the generation of various wavelength conversion patterns which play an important role for OPS performance. The converted signals after two stages of PWC are obtained with error-free operations and low power penalties (BER=10^?9) of about 2.0 dB. Numerical results also show significant improvement in packet blocking probability by the proposed recursive PWC-based OPS in comparison with the previous non-recursive schemes.     

Demonstration of 100 Gbps optical packet switching using header processor based on 48-bit longest prefix matching

Wire-rate packet processing and its energy saving for over 100 Gbps speed of line are major issues to be resolved in optical packet switching (OPS) networks. For that purpose, we newly develop a high-speed, deterministic-latency electronic header processor based on longest prefix matching (LPM) for searching optical packet destination addresses (OP-DAs). This paper reports the successful experimental results of electronic header processing based on LPM search of up to 48 bits and optical switching of 100 Gbps optical packets by the use of the header processor. We demonstrate 48-bit LPM-capable optical packet switching. We also demonstrate IP packet transfer and 32-bit LPM-capable optical packet switching. In the latter demonstration, the 32-bit OP-DA of optical packets is directly copied from the 32-bit destination address of Internet Protocol version 4 (IPv4) packets. This result indicates that OPS networks can be deployed with electronic IP networks by the use of integrated network operation between OPS and IP networks.     

The study of QoS guarantee in the optical burst switching internet backbone

Optical switching technology can be categorized into optical circuit switching (OCS), optical packet switching (OPS) and optical burst switching (OBS). OCS is suitable for large amounts of data transmission; however, the channel utilization is inefficient when the traffic flows are intermittent. OPS can be easily adapted to any higher layer and is suitable for bursty traffic, but it requires a highly complex technology and optical buffer. The new switching paradigm, OBS, can provide higher bandwidth utilization and meanwhile avoid the complexity in OPS technology.In this paper, we investigate how the quality of service (QoS) can be guaranteed and reliable transmission can be supported in the OBS-based Internet backbone. We propose the adjustable-time-counter-based (ATCB) burst assembly and the non-real time packet retransmission mechanisms and apply them in the ingress router of the OBS Internet backbone to guarantee the quality of real time applications and lossless requirement of non-real time services. Moreover, traffic shaped is performed for real time packets in the egress router so that the real time property is preserved with a low jitter. Simulation results show that the burst blocking probability using the ATCB burst assembly is improved, compared with the time-counter-based (TCB) and burst-length-threshold-based (BLTB) mechanisms. The delay, loss and jitter of real time service conform to the QoS requirement. Meanwhile, the delay of non-real time service also falls in the acceptable range.     

High-Performance Hybrid-Switching Optical Router for IP over WDM Integration

Because pure electrical routers with their bandwidth limitations can hardly keep up with the tremendous traffic growth in the Internet, optical routers based on various optical switching techniques including optical wavelength switching (OWS), optical burst switching (OBS), and optical packet switching (OPS) have been suggested to cope with this problem. However, because OBS and OPS are both in their early experimental phase and OWS only provides coarse granularity switching, a hybrid-switching optical router with combined OWS and electrical packet switching is a necessity in order to accommodate the entire multi-granularity traffic with multi-service requirements in a cost-effective manner. Its coordination capability of optical circuit switching and electrical packet switching enables efficient/intelligent usage of network resources. In this paper, we first review research and developments of such IP routers employing optical switching/interconnection techniques and examine how these techniques can be used inside routers to scale node capacity and to improve optical Internet performance. We also present and study the performance of a terabit optical router with an optical-electrical hybrid-switching fabric. The node architecture is based on the idea of IP over WDM integration with Generalized Multi-Protocol Label Switching (GMPLS). The network-level performance evaluations show that the proposed hybrid-switching optical router is a cost-effective solution for building the next generation GMPLS-based multi-granularity optical Internet.     

Analytical MMAP-Based Bounds for Packet Loss in Optical Packet Switching with Recirculating FDL Buffers

The major goal of optical packet switching (OPS) is to match switching technology to the huge capacities provided by (D)WDM. A crucial issue in packet switched networks is the avoidance of packet losses stemming from contention. In OPS, contention can be solved using a combination of exploitation of the wavelength domain (through wavelength conversion) and buffering. To provide optical buffering, fiber delay lines (FDLs) are used. In this paper, we focus on an optical packet switch with recirculating FDL buffers and wavelength converters. We introduce the Markovian arrival process with marked transitions (MMAP), which has very desirable properties as a traffic model for OPS performance assessment. Using this model, we determine lower and upper bounds for the packet loss rate (PLR) achieved by the aforementioned switch. The calculation of the PLR bounds through matrix analytical methods is repeated for a wide range of traffic conditions, including highly non-uniform traffic, both in space (i.e., packet destinations) and time (bursty traffic). The quality of these bounds is verified through comparison with simulation results.