Optical Network Infrastructure Research Articles

Converged Optical Network Infrastructures in Support of Future Internet and Grid Services Using IaaS to Reduce GHG Emissions

With the rapid and growing volume of green house gas (GHG) we may soon cross a tipping point where there may be dramatic climatic catastrophes such that governments will be forced to order the shutdown of coal powered electrical production or mandate carbon neutrality across all sectors of society. On the other hand, in the event of such a development, the future Internet and Grid infrastructure may become absolutely essential for communications and a replacement for travel and for the delivery of critical services such as health, education, research, etc. Information and Communication Technologies (ICT) produce 2%-3% of the world's GHG emissions through the consumption of electricity largely produced by coal plants. This rate of GHG is expected to double in the next few years and is clearly unsustainable. Therefore it is critical that any future Internet and Grid infrastructure be designed not only to survive, but also be sustained, through an age where no additional GHG emissions will be allowed. Converged optical networks, Grid and cloud services hosted at zero carbon renewable energy sites using Infrastructure as a Service (IaaS) where each network and computer element is represented to a user as a configurable virtual service will allow for the deployment of what are often referred to as ldquofollow the sun or follow the windrdquo optical network and Grid architectures where the network and Grid topology and Grid resources availability and location are constantly changing depending on local availability states of the wind or sun.

Spectrally efficient hybrid multiplexing and demultiplexing schemes toward the integration of microwave and millimeter-wave radio-over-fiber systems in a WDM-PON infrastructure

Hybrid multiplexing and demultiplexing schemes with the capability to integrate microwave and millimeter-wave frequency radio-over-fiber signals in a wavelength division multiplexed passive optical network (WDM-PON) infrastructure are proposed. The proposed schemes exploit the benefits of a spectrally efficient wavelength-interleaving technique and enhance the performance of optical millimeter-wave signals without employing an additional device. The schemes are demonstrated experimentally with simultaneous transport of 1 Gbit/s baseband, 2.5 GHz microwave, and 37.5 GHz millimeter-wave signals that have the potential to converge last-mile optical and wireless technologies, leading to an integrated dense WDM network in the access and metro domains.

Architecture to integrate multiple PONs with long reach DWDM backhaul

This paper demonstrates the feasibility of an architecture that consolidates a number of deployed Passive Optical Network (PON) infrastructures into a long-reach, high-split ratio system which further increases equipment sharing between users. The demonstrated system allows the use of uncooled lasers with possible wavelength drift across a CWDM band (20 nm) with optical amplification and narrow optical filtering with no performance degradation. A complete study of potential implementations was performed with experimental results showing that a target performance of 10-10 could be achieved over 120 km of standard fiber with transmitter wavelengths from 1542 to 1558 nm and DWDM backhaul wavelengths from 1520 to 1535 nm. This gives the potential to support up to 2560 users.

Performance Comparison of Directly Modulated VCSEL and DFB Lasers in Wired-Wireless Networks

We compare the RF power conversion efficiency using our analytical model for optical links composed of distributed feedback (DFB) and vertical-cavity surface-emitting laser (VCSEL) optical sources. We then experimentally compare RF power consumption and present link transmission performance for a directly modulated DFB laser-based and VCSEL-based hybrid access network overlaid on an ethernet passive optical network infrastructure for the distribution of wired and wireless services.

Evolving the Optical Transport Network Management to Integrate Multiple Technologies and Services

Optical networks are evolving at a fast pace from traditional synchronous digital hierarchy/synchronous optical network (SDH/SONET) and wavelength division multiplexing (WDM) infrastructures, used by client network layers in overlay mode, to a converged multi-service and multi-technology network able to transport traditional time division multiplexing (TDM) traffic and new packet traffic in a flexible way. Alcatel-Lucent is leading the network transformation required by network providers to offer data transport while guaranteeing the same quality and reliability typical of classical transport services. The introduction of new data communication services requires an evolution of the network management platform that needs to integrate new management applications associated with the new technologies and services. The resulting network has to be integrated from service provisioning and management system viewpoints to optimize its use and to reduce the in-field modifications of the transport network. This article describes specificities in the management of multi-service networks, identifying the management architecture able to support the rapid evolution of such environment.

Optimization for Optical Network Designs Based on Existing Power Grids

In a power grid used to distribute electricity, optical fibers can be inserted inside overhead ground wires to form an optical network infrastructure for data communications. Dense wavelength division multiplexing (DWDM)-based optical networks present a promising approach to achieve a scalable backbone network for power grids. This paper proposes a complete optimization procedure for optical network designs based on an existing power grid. We design a network as a subgraph of the power grid and divide the network topology into two layers: backbone and access networks. The design procedure includes physical topology design, routing and wavelength assignment (RWA) and optical amplifier placement. We formulate the problem of topology design into two steps: selecting the concentrator nodes and their node members, and finding the connections among concentrators subject to the two-connectivity constraint on the backbone topology. Selection and connection of concentrators are done using integer linear programming (ILP). For RWA and optical amplifier placement problem, we solve these two problems together since they are closely related. Since the ILP for solving these two problems becomes intractable with increasing network size, we propose a simulated annealing approach. We choose a neighborhood structure based on path-switching operations using k shortest paths for each source and destination pair. The optimal number of optical amplifiers is solved based on local search among these neighbors. We solve and present some numerical results for several randomly generated power grid topologies.

Admission control in data transfers over lightpaths

The availability of optical network infrastructure and appropriate user control software has recently made it possible for scientists to establish end-to-end circuits across multiple management domains in support of large data transfers. These high-performance data paths are typically provisioned over 10 Gigabit optical links, and accessed using ethernet encapsulation at Gigabit and 10 Gigabit rates. The resulting mixture of circuit sizes gives rise to resource conflicts whereby requests to allocate bandwidth partitions are blocked despite vast underutilization of the optical link. In an attempt to remedy this problem, we investigate intelligent admission control policies that consider the long-term effects of admission decisions. Using analytic techniques we show that the greedy policy, which accepts requests to allocate bandwidth partitions whenever sufficient bandwidth exists, is suboptimal in a pertinent scenario. We then consider dynamic online computation of the optimal admission control policy and show that the acceptance ratio of requests to establish end-to-end circuits can be improved by up to 19% on a fifteen-node network where the behaviour of each link is governed by a local optimization effort.

Future Optical Networks

This paper presents views on the future of optical networking. A historical look at the emergence of optical networking is first taken, followed by a discussion on the drivers pushing for a new and pervasive network, which is based on photonics and can satisfy the needs of a broadening base of residential, business, and scientific users. Regional plans and targets for optical networking are reviewed to understand which current approaches are judged important. Today, two thrusts are driving separate optical network infrastructure models, namely 1) the need by nations to provide a ubiquitous network infrastructure to support all the future services and telecommunication needs of residential and business users and 2) increasing demands by the scientific community for networks to support their requirements with respect to large-scale data transport and processing. This paper discusses these network models together with the key enabling technologies currently being considered for future implementation, including optical circuit, burst and packet switching, and optical code-division multiplexing. Critical subsystem functionalities are also reviewed. The discussion considers how these separate models might eventually merge to form a global optical network infrastructure

Algorithms for multicast traffic grooming in WDM mesh networks

Several of the new applications in high-performance networks are of the multicast traffic type. Since such networks employ an optical network infrastructure, and since most of these applications require subwavelength bandwidth, several streams are usually groomed on the same wavelength. This article presents an account of recent advances in the design of optical networks for multicast traffic grooming in WDM mesh networks. The article addresses network design and session provisioning under both static and dynamic multicast traffic. Under static traffic conditions, the objective is to accommodate a given set of multicast traffic demands, while minimizing the implementation cost. Optimal and heuristic solution techniques for mesh network topologies are presented. Under dynamic traffic conditions, techniques for dynamic routing and session provisioning of multicast sessions whose objective is to minimize session blocking probabilities are explained. The article also presents a number of open research issues

Hybrid DWDM-TDM long-reach PON for next-generation optical access

A novel long-reach passive optical network (PON) architecture based on hybrid dense wavelength-division multiplexing (DWDM) and time-division multiplexing (TDM) is presented as a possible candidate for the next generation of optical access networks. The approach combines access and backhaul functions in a single optical network infrastructure that links end customers directly to core networks without the need for intermediate electronic conversions. A centralized optical carrier distribution and wavelength-independent remote modulation scheme is employed to avoid the potential inventory and deployment costs associated with the use of wavelength-specific lasers in the customer transmitter (TX). The customer TX is based on an electroabsorption modulator (EAM) monolithically integrated with two semiconductor optical amplifiers (SOAs), providing sufficient net gain and bandwidth to support large splitting factors and upstream bit rates up to 10 Gb/s. The experimental results reported show that the network, with a total reach of 100 km and an upstream bit rate of 10 Gb/s, can potentially support 17 TDM PONs operating at different wavelengths each with up to 256 customers, giving an aggregate number of 4352 customers in total.

Signaling architectures and recovery time scaling for grid applications in IST Project MUPBED

It is now evident to the research community that local computational resources cannot keep up in an economical way with the demands generated by some users/applications. Therefore, distributed computing and the concept of a computational grid are now emerging. Novel transport network concepts are needed to support such visions, and high-speed intelligent optical networking may be the required infrastructure that will enable global grids. Emerging utility grid applications like business continuity and disaster recovery have strong requirements on the dynamic optical networks connecting the distributed grid resources. Supporting grid networking with an intelligent optical network (ION) infrastructure will allow utility grid applications the necessary flexibility with the required QoS (e.g., high bandwidth, reliability, limited delay). Emerging QoS requirements, such as scalable recovery time, highly depend on the ION's signaling architecture. This article gives simple analytical models for the implementation options of optical control plane signaling, shows simulation models for different resilience strategies, and offers some illustrative numerical comparisons to support the aforementioned efforts. This research area is also discussed, among others, in the European research project Multi-Partner European Testbeds for Research Networking (MUPBED).

Verizon experience with NG Ethernet services: evolution to a converged layer 1, 2 network

This article presents Verizon's experience with deploying metro Ethernet services and some of our laboratory activities related to the convergence of layer 2/1 networks. Such convergence leverages the existing SONET and optical transport network infrastructure, and integrates layer 1 and layer 2 transport, control, and management planes within the network. Integrated service provisioning is featured, including service logic and policy that controls the admission, path selection, and transport bandwidth adjustment requirements of provisioning an Ethernet virtual connection within the metro Ethernet network.

Distributed Route Computation and Provisioning in Shared Mesh Optical Networks

Optical mesh network infrastructure has emerged as the technology of choice for next-generation transport networks. At the same time, distributed, IP-based, control architecture has been proposed for intelligent optical networks, as a means to automate operations, enhance interoperability, and facilitate the deployment of new applications. While distributed control in general enhances scalability and flexibility, it has also been observed that the requisite network topology and link-state information summarization may result in suboptimal path computation, especially for shared mesh restored paths. This paper presents a distributed control plane for optical mesh networks, focusing on distributed path computation and provisioning mechanisms. It discusses the tradeoffs between the path computation efficiency for shared mesh restored paths and the amount of network topology and link-state information that is disseminated via routing protocols. We show that with appropriately aggregated link resource availability and sharing information, the proposed distributed path computation algorithms are able to determine the shareability of restoration links with remarkable accuracy. A local channel assignment scheme, which is used in conjunction with the distributed path computation algorithms to assign shared channels when provisioning restoration paths, is also proposed. The additional information that signaling messages are required to carry in order to perform the local channel assignment at each node along the restoration path is discussed. Furthermore, we specify the extensions to the open shortest-path first (OSPF) routing protocol in support of shared mesh restoration. We analyze the performance of the proposed distributed path computation algorithms and the local channel assignment scheme, as well as the overhead of OSPF extensions. In particular, we study the tradeoffs between network capacity utilization, restoration path computation complexity, OSPF extension overhead, and memory requirements for storing the modified link-state database.

Extension of all-optical network-transparent domains based on normalized transmission sections

This paper presents a technique that significantly simplifies the design and operation of transparent optical wavelength-division-multiplexing (WDM) networks. Since most of the signal degradations arise due to the interaction of linear and nonlinear physical effects along the fiber links, a link design concept based on erbium-doped fiber amplification is developed and optimized such that originally degrading effects mutually compensate each other, leading to approximately noise-limited transmission. In extensive numerical simulations as well as laboratory experiments, an optimized modular link design is identified. Regenerator-free transmission of a single-channel 10-Gb/s nonreturn-to-zero signal over 4000 km is achieved in a recirculating loop experiment with less than a 3-dB penalty. Reliable WDM transmission is demonstrated over 1600 km, showing the high robustness of this concept. Finally the link design concept is applied in a WDM field trial using deployed standard single-mode fibers (S-SMFs) of the optical network infrastructure of Deutsche Telekom. Between the German cities of Berlin and Darmstadt, 10-Gb/s synchronous digital hierarchy (SDH)-based data, 10-Gb/s duobinary-encoded data, and a native Gigabit Ethernet signal have been transmitted error-free over a maximum distance of 1720 km, thus demonstrating the feasibility of the design concept under realistic field conditions. The presented design approach substantially supports link setup and rerouting procedures by supplying simple rules to identify the maximum number of dispersion-compensated S-SMF amplified spans which can be cascaded for a given tolerable penalty.

A practical vision for optical transport networking

Optical transport networks (OTNs) will quickly evolve from dense wavelength division multiplexed (DWDM) remedies for capacity exhaust to scalable and robust optical networking applications catering to a wide variety of client signals with equally varied service requirements. This paper presents a practical vision for OTN evolution, placing it in the context of other networking trends. It also provides a brief introduction to the papers presented in this issue, which together provide a view of Lucent Technologies' Network Vision for a cost-effective, survivable, and flexible broadband optical networking infrastructure.

Design of a cross-border optical core and access networking field trial: first outcomes of the ACTS-PELICAN project

A large advanced optical network was assembled and operated in the field, featuring access, metropolitan, and core optical networks with advanced functionality and technology in all parts of the network. It demonstrates the reliability and viability of photonic technologies, and management functions in a trial representative of a global network infrastructure. The core network is a transparent all-optical meshed network with wavelength crossconnects partly 2R-regenerating, operating at 2.5 and 10 Gb/s, and supporting various protection schemes including 1:N shared OCH protection. The metropolitan network is a ring composed of OADMs supporting OMS protection. The interconnection to the SuperPON access network is made through an ATM switch. The ATM-based SuperPON supports a dynamic medium access control (MAC) protocol. For the first time, a 10 Gb/s wavelength-converted connection was demonstrated in the field in a transparent all-optical managed network. The field trial has demonstrated many points of progress as compared to the previous state of the art: cascadability experiments in a real network with reasonable distances and low compensation, various node functions, interworking of various equipment types, new optical protection, and dynamic MAC protocol. The (transport) TMN/Q3 integrated management system played an important role to achieve the network experiments: it allowed us to provision and reconfigure the end-to-end optical paths very quickly (<3 s) from the centralized management platform. This trial is also the first one representative of an advanced global optical network infrastructure including core, metro, and access networks, supporting end-to-end multimedia services. This article reports the project results before the field deployment which took place in April 2000.

Optical data networking

We challenge current thinking about IP over WDM by outlining a path to optical data networking that includes multiple data networking protocols coupled with a protocol-neutral optical networking infrastructure. Included is a discussion of the diversity of data networking protocols and network architectures for optical data networking.

Wavelength-tolerant optical access architectures featuring N-dimensional addressing and cascaded arrayed waveguide gratings

This paper describes two- and three-stage wavelength routed optical access networks, which offer wavelength tolerance by using coarse passband-flattened arrayed waveguide grating routers. An N-dimensional addressing strategy enables 6912 customers to be bidirectionally accessed with multi-Gb/s data using only 24 wavelengths and 1.6 nm spacing. These architectures are designed to map onto standard access network topologies, allowing elegant upgradability from legacy passive optical network (PON) infrastructures at low cost.

SONET implementation

The status of the synchronous optical network (SONET) infrastructure development and deployment are examined to see whether or not they meet original expectations. Issues arising from deployment, such as the use of new features and the necessary support from operations systems, and future directions of SONET are discussed. These future trends include digital cross connect systems (DCSs), SONET ring architectures, and hybrid ring-DCS networks. New SONET services are also discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>