Optical Packet Switching Networks With Binary Multiwavelength Labels

We propose a network structure for routing optical packets based on binary multiwavelength labels. We resolve the main drawbacks of previously proposed optical label switching scenarios: high splitting loss and complex, expensive hardware. In our scheme, the label is mapped bit-by-bit to a selection of wavelength bins. Variable-length packets are self-forwarded via a multistage switch. This structure is scalable, high-speed, simple, practical, and low-cost, exploiting the workhorses of today's optical communications systems: arrayed waveguide gratings, distributed feedback lasers, ${rm LiNbO}_{3}$ switches, and low-speed photodiodes and electronics ($sim {hbox {100}},{hbox {MHz}}$). We also propose a solution to alleviate the sophisticated label swapping processing required in generalized multiprotocol label switching (GMPLS) networks. We time-multiplex the binary multiwavelength labels for the entire optical label switching path. We examine the performance of both schemes experimentally by verifying successful routing and error-free transmission.      

High-capacity multiservice optical label switching for the next-generation Internet

This article presents an optical label switching technology geared toward the next-generation Internet, and highlights its promising potential to accommodate packet, burst, and circuit traffic in a unified optical layer. In particular, we provide detailed discussions on an architecture design for a high capacity optical label switching router by considering enabling optical technologies. In pursuit of an effective contention resolution scheme, we investigate an end-to-end solution by incorporating a traffic shaping function at the network edge with wavelength, time, and space dimensions contention resolution in the core network. Experimental results indicate that this scheme is capable of achieving very low packet loss rates. Furthermore, due to its natural compatibility with GMPLS architecture, optical label switching has great potential for a seamless upgrade of today's optical networks toward the next generation Internet.     

On Architecture and Limitation of Optical Multiprotocol Label Switching (MPLS) Networks Using Optical-Orthogonal-Code (OOC)/Wavelength Label

To accommodate the explosive packet-based data traffic in WDM networks, intelligent optical routing and switching are required in optical transport networks. Optical multiprotocol label switching networks emerged to meet this demand. In this paper, different schemes for implementing an OMPLS network are introduced. An optical MPLS network using OOC/wavelengths as labels is proposed. Based on an all-optical code converter, the architecture of the optical core router is demonstrated. The fundamental limits on scalability of the proposed core router, namely the label capacity, and the blocking probability of the label switched path setup are investigated, and closed-form solutions are derived.     

Field Trial of All-Optical Networking Controlled by Intelligent Control Plane With Assistance of Optical Performance Monitors

A field trial of all-optical networking by an intelligent control plane based on generalized multiprotocol label switching (GMPLS) technologies was successfully conducted with the assistance of optical performance monitors (OPMs) capable of monitoring the in-band optical signal-to-noise ratio (OSNR). In the field trial, the GMPLS control plane was applied to not only fast provisioning of all-optical paths but also to end-to-end restoration of optical paths triggered by OPMs. Reliable and stable network operation was achieved as a result of applying the GMPLS control plane and OPMs.      

Wavelength Routing Algorithm of All Optical Network Based on Traffic Engineering

General multi-protocol label switching （GMPLS） based on traffic engineering is one of the possible methods to implement all-optical network. This method implements the network with IP technique and guarantees the quality of service with traffic engineering. Based on the establishment of selecting schemes of optical path and methods of traffic calculation, the wavelength routing algorithm of all-optical network based on traffic engineering is presented by combining with prior route of shortest path and traffic engineering, the algorithm procedures are given, and the actual examples are introduced as well as the analysis on simulation calculation. This research results have certain significance for the achievement of optical switching technique of all-optical network.     

通用多协议标签交换技术研究

通用多协议标签交换技术(GMPLS)在光交换网中具有广阔的应用前景,但对它的研究还不够深入.首先指出GMPLS与传统的标签交换技术(MPLS)在7个方面的区别,然后刻画GMPLS光网络的一般结构,对特点进行了分析,指出光IP包交换的实质是光标记的转发与交换.设计了GMPLS光网络的技术方案,对关键技术进行分析,提出了一...     

An experimental switching-aware GMPLS-based lightpath provisioning protocol in wavelength-routed networks

In wavelength-routed optical networks, the high-delay introduced by the optical switching fabric for resource reservation increases critically the lightpath setup delay. In order to minimize the setup delay, Generalized Multi-protocol Label Switching (GMPLS) introduced the concept of Suggested Label Object (SL), which allows to start reserving and configuring the hardware with a proposed wavelength from the source node to the destination node. This solution is not optimal in wavelength selective networks (WSN) (i.e., without wavelengths converters). The need of guaranteeing the wavelength continuity constraint for end-to-end optical connections, combined with the lack of global wavelength-based link information (the source node is not aware of which wavelengths are available on each link), makes that the likelihood of establishing a lightpath using the proposed suggested label may be minimum. In this article, we propose an enhancement to the current GMPLS RSVP-TE signaling protocol with offset time-based provisioning that minimizes the lightpath setup, improving the overall network performance in terms of blocking probability and setup delay. Experimental performance evaluation has been carried out in ADRENALINE testbed, a GMPLS-based intelligent all-optical transport network.     

光码分多址全光网络实现方案

本文提出一种利用时域编码的光码分多址(OCDMA)技术构造全光通信网络的实现方案.给出了OCDMA全光接入网,OCDMA光交叉连接、光交换、光上下路、光复用的具体实现方法,给出了OCDMA全光网络体系结构.     

OCDMA技术的研究现状及发展

OCDMA技术是新一代的全光技术,可以广泛用于光信道多路复用、光网络多址接入、光码标记交换核心网、光信号安全传输、光纤传感以及光栽无线系统等.概述了光码分多址(OCDMA)技术的研究现状、主要关键技术,并展望其发展趋势和应用前景.     

All-Optical Switches in Optical Time-Division Multiplexing Technology: Theory, Experience and Application

All-Optical Switches in Optical Time-Division Multiplexing Technology: Theory, Experience and Application     

GMPLS协议中的路由和波长分配技术

因特网工程工作组（IETF）制定的通用多协议标签交换协议（GMPLS）,作为光网络的控制平面协议,推动了光网络的智能化进程。路由和波长分配问题（RWA）是光网络智能化的核心问题之一。在介绍RWA算法和GMPLS协议的基础上,分析了不同RWA算法、不同RWA机制对网络信息的需求,描述了GMPLS协议为解决RWA问题所做的标准化工作,并分析了与RWA相关的网络信息分发格式。     

Design and experimental demonstration of a variable-length optical packet routing system with unified contention resolution

This paper presents theoretical design, network simulation, implementation, and experimental studies of optical packet routing systems supporting variable-length packets. The optical packet switching network exploits unified contention resolution in core routers in three optical domains (wavelength, time, and space) and in edge routers by traffic shaping. The optical router controller and lookup table, implemented in a field-programmable gate array (FPGA), effectively incorporates the contention resolution scheme with pipelined arbitration of asynchronously arriving variable-length packets. In addition, real-time performance monitoring based on the strong correlation between the bit-error rates of the optical label and those of the data payload indicates its application in optical time-to-live detection for loop mitigations. Successful systems integration resulted in experimental demonstration of the all-optical packet switching system with contention resolution for variable-size packets.     

All-optical wavelength-path service with quality assurance by multilayer integration system

In the future all-optical network controlled by generalized multiprotocol label switching (GMPLS), the wavelength path between end nodes will change dynamically. This inevitably means that the fiber parameters along the wavelength path will also vary. This variation in fiber parameters influences the signal quality of high-speed-transmission system (bit rates over 40 Gb/s). Therefore, at a path setup, the fiber-parameter effect should be adequately compensated. Moreover, the path setup must be completed fast enough to meet the network-application demands. To realize the rapid setup of adequate paths, a multilayer integration system for all-optical wavelength-path quality assurance is proposed. This multilayer integration system is evaluated in a field trial. In the trial, the GMPLS control plane, measurement plane, and data plane coordinated to maintain the quality of a 40-Gb/s wavelength path that would otherwise be degraded by the influence of chromatic dispersion. It is also demonstrated that the multilayer integration system can assure the signal quality in the face of not only chromatic dispersion but also degradation in the optical signal-to-noise ratio by the use of a 2R regeneration system. Our experiments confirm that the proposed multilayer integration system is an essential part of future all-optical networks.     

STOLAS: switching technologies for optically labeled signals

GMPLS-based labeled optical burst switching (LOBS) networks are being considered as the next-generation optical Internet. GMPLS includes wavelength switching next to label and fiber (space) switching. We present a new concept of optically labeling bursts of packets suitable for LOBS networks supported by GMPLS. It is based on angle modulation, which enables control information to modulate the phase or frequency of the optical carrier, while payload data are transmitted via intensity modulation (IM). In particular, the optical label is orthogonally modulated, with respect to the payload, using either frequency shift keying or differential phase shift keying. We present a performance analysis of the modulation schemes by means of simulations where the influence of the payload IM extinction ratio and laser linewidth are investigated. In addition, the transmission performance of an IM/FSK combined modulated signal is experimentally validated at 10 Gb/s, demonstrating at the same time an FSK label swapping operation. Finally, a suitable optical label-controlled switch design is proposed that takes advantage of these novel labeling techniques, and efficiently combines widely tunable, fast switching lasers and SOA-MZI wavelength converters with an arrayed waveguide grating router.     

Performance Analysis of Infrastructure Service Provision with GMPLS-Based Traffic Engineering

Dynamic sharing of the common physical network is envisioned as a key enabler for the emerging Internet technologies. This paper addresses challenges related to resource sharing in the physical layer and analyzes the performance of infrastructure service provision with control plane mechanisms based on generalized multi protocol label switching (GMPLS). In our approach, the provisioning of infrastructure services is supported by two novel concepts for GMPLS traffic engineering (TE): resource visibility and inter-domain exchange. Resource visibility is a new network control plane concept, which defines the usage polices for transmission, multiplexing, and switching resources in multiple GMPLS layers. In our architecture, every network resource may exhibit different visibility to different services at different layers. The inter-domain exchange, here referred to as GMPLS exchange point (GXP), is the physical layer equivalent of the Internet exchange point (IXP). Just as how the IXP manages interconnections of autonomous systems (AS) in the Internet, the GXP manages dynamic interconnections of multiple provider domains and enables them to advertise their physical resources to other domains. We model the dynamic provisioning of infrastructure services using graph theory and deploy GMPLS traffic engineering (TE) to optimize the routing and resource yields. The results obtained demonstrate that traffic engineering with resource visibility and GXP brings significant performance benefits in resource utilization and infrastructure extensibility, especially when network providers set up LSPs as a result of collaborative and carrier-neutral traffic engineering where they share information about resource capabilities and utilization     

Resilience in GMPLS path management: model and mechanism

The recent advent of converging the IP and optical networks has necessitated the development of a generalized multiprotocol label switching framework. Resilience becomes more important than ever before in a GMPLS network since a single cut of an optical fiber may generate hundreds of link and node failures at high layers of the GMPLS architecture. In this article we briefly survey the current work regarding GMPLS recovery management, and present a new resilience-based dynamic GMPLS path management strategy. We present a simple model to represent the resilience requirements in GMPLS path management, and propose fast path management algorithms. The salient feature of the proposed approach is that it enables the paths to be dynamically selected under multiple simultaneous failure occurrences while satisfying the resilience requirement. Backup path design rules are developed, and the condition for backup path availability is derived for the special mesh-type GMPLS network. Finally, a simple example is shown to illustrate the effectiveness of the proposed resilience model and path management mechanism.     

Waveband grooming and IP aggregation in optical networks

An automatically switched optical network (ASON) can be used as the transport layer of generalized multiprotocol label switching (GMPLS) networks. The design of an ASON involves determining the number of optical cross-connects (OXC) in the network, the required number of ports per OXC, and the interconnection topology of the OXCs. Given the number of ports per OXC, we present a linear algorithm to find the number of OXCs and to identify a cost-effective topology. We then develop a scheme that can be used to perform waveband grooming for several different topologies of an ASON that uses single-layer multigranular OXCs. We identify the bottlenecks and investigate the effect of traffic grooming schemes in the design of an ASON as a function of the peak access rate per customer. We evaluate the topologies and architectures for a national trunk network.     

Optical burst switching: a viable solution for terabit IP backbone

Wavelength-division multiplexing has emerged as an important physical layer technology. Optical transmission provides a physical layer capable of carrying bits at the speed at the order of a gigabit per second. Optical burst switching is proposed to overcome the shortcomings of conventional WDM deployment, such as lack of fine bandwidth granularity in wavelength routing and electronic speed bottlenecks in SONET/SDH. We describe an architecture for IP network over the OBS WDM transmission core. The use of MPLS-type technique for forwarding data bursts and the inclusion of a medium access control layer between the optical (WDM) and IP layers are the key ingredients of the proposed architecture. In particular, the architecture is based on provisioning MPLS paths, also called label switched paths, of desired quality of service through the OBS WDM transmission core. The MAC layer performs various OBS-specific functions, such as burst assembly, burst scheduling, and offset setting/traffic shaping. While burst assembly and burst scheduling are relatively straightforward, we point out that the offset setting strategy has significant impact on the performance of IP network operating over OBS WDM core. We describe a shaping scheme to set the offset, an important system parameter for OBS, between the successive data bursts of a given data stream (label switched path) and their associated control packets. This scheme results in robust operation of the network and also facilitates traffic engineering. Guidelines are provided for implementing various IP QoS mechanisms in the optical backbone using OBS.     

Design of All-Optical Contention Detection and Resolution for 40-Gb/s Label-Switched Routers

We present a new scheme for all-optical contention detection and time-domain contention resolution of optical packets in label-switched routers that employ all-optical label recognition. The contention detection subsystem provides all the necessary control signals required to drive an optically controlled buffer which employs 1 times 2 optical switching elements and an optical fiber delay line. The state of the buffer is dynamically controlled on a per-packet basis with all the decisions and processing performed in the optical domain. Physical layer simulations show successful buffering and forwarding of 40-Gb/s optical packets with 2-dB power penalty     

基于GMPLS的OBS网络技术

GMPLS(通用多协议标签交换)是MPLS技术向光网络发展的产物。描述GMPLS和MPLS控制平台的区别,介绍引用GMPLS协议作为控制平面的OBS网络。提出的网络结构是在OBS的突发控制包中用通用标签代替源节点和目的节点地址,并使用GMPLS协议栈对路由协议、信令功能以及链路管理协议进行增强和扩展以便更好地支持OBS网络。