Advances in Optical Networks and Components

Partha Pratim Sahu

• Publisher: CRC Press
• Year: 2020
• eBook ISBN: 9781000060645
• Edition: 1
• Topic: Computer Science
• Subtopic: Optical Data Processing
• Index: Computer Science

This book is intended as a graduate/post graduate level textbook for courses on high-speed optical networks as well as computer networks. The ten chapters cover basic principles of the technology as well as latest developments and further discuss network security, survivability, and reliability of optical networks and priority schemes used in wavelength routing. This book also goes on to examine Fiber To The Home (FTTH) standards and their deployment and research issues and includes examples in all the chapters to aid the understanding of problems and solutions.

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• Presents advanced concepts of optical network devices

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• Includes examples and exercises inall the chapters of the book to aid the understanding of basic problems and solutions for undergraduate and postgraduate students

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• Discusses optical ring metropolitan area networks and queuing system and its interconnection with other networks

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• Discusses routing and wavelength assignment

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• Examines restoration schemes in the survivability of optical networks

1 Optical Ring Metropolitan Area Networks

Communications networks are represented as three-tier hierarchical networks having access to a long-haul wide area network. At the bottom of the hierarchy, there is an access network connecting to customers/users within close proximity averaging regions between 10–100 km and interconnecting the access and long-haul networks. The access networks have already been discussed in Chapter 9 of volume 1. Long-haul optical backbone networks provide a coverage of interregional/global distances (2000 km or more) for transmission of signals. Metropolitan area networks (MANs) use synchronous digital hierarchy (SDH)/synchronous optical network (SONET) architecture [1–3] (as discussed in Chapter 1 of volume 1) and are placed in between the access network and long-haul optical backbone [4–29]. For example, the smaller rings having OC-3/STM-l (155 Mbps) or OC-12/STM-4 (622 Mbps) traffic are combined into larger core inter-office (IOF) rings that interconnect central office (CO) locations at higher bit rates; e.g., OC-48/STM-16 (2.5 Gbps) Synchronous Transport Signal (STS) uses transmission of frame structure in electrical domain wave for end-user connectivity, namely voice. Internet data traffic growth is basically considered for metropolitan optical network. As the number of users and traffic/services increases, the networks require higher bandwidth for the Internet users using optical wavelength division multiplexing (WDM) technology.

1.1 Different MANs

WDM technology is used in the backbone networks to enhance the capacity to the range of terabits. The access technology does the sharing of a large number of signals. Residential and digital subscriber line (DSL) modems provide access rates ranging from kbps to Mbps and other advanced technologies such as passive optical networks (PONs) (Chapter 9 of volume 1). Also, customers employ advanced switching/routing capable of direct line-rate inputs to the metro core having OC-48/192 and 10 Gbps Ethernet interfaces. Many SONET/SDH rings operate with the capacities of OC-48/192 rates. These backbones comprise IP (Internet Protocol), ATM (Asynchronous Transfer Mode), SONETISDH, Ethernet (10/100 Mbps, 1.0/10 Gbps), multiplexed time division multiplexers (TDMs) voice, and other more specialized data protocols such as ESCON (Enterprise System Connectivity), FICON (Fiber Connectivity Channel) [4], Fiber Channel, cable video, etc.

The new MANs offer alternative networks for wide areas using SONET/SDH expansion [3]. The MANs should provide high bandwidth capability and use multiple protocols over a common infrastructure to increase link utilization. Intelligent service provisioning and survivability [1] are essential for advanced service-level agreements (SLAs) [5]. Moreover, new schemes offer backward compatibility for a more cost-effective network. Tunable optical sources, optical fibers, receivers, and tunable switches are required for enabling network-level wavelength routing and protection over rings or meshes. These capabilities with intelligent control architectures make the operators provide more capacity to a large number of services [6].

WDM technology offers many benefits with its deployment within MAN, but its use in a network is complex [7]. For WDM use in a larger metro area backbone, scalable “lambda” provisioning is required in Gbps range. In a MAN, operators interface with increased protocol heterogeneities, namely, interfaces and bit rates, and a MAN needs to cost-effectively handle finer “sub-wavelength” capacity increments. In long-haul networks, the input signals comprise a few protocols (SONET/SDH) [3] and interface bit rates (2.5, 10, and possibly 40 Gbps) which perform multi-protocol aggregation/grooming onto larger WDM branches, with a particular focus on data protocol efficiency. Various signal solutions are driven by advances in high-density electronic integrated circuit (IC) technology, e.g., SONET/SDH multi-service provisioning platforms (MSPPs) [8] and IP packet rings.

1.2 Metro WDM Networks

The growth of optical technology requires electronics for the MANs in case of bottlenecks in the network. WDM is used in long-haul backbones providing a high-speed/high-bandwidth network. The terms “transparent” and “all-optical” represent entities (nodes, networks). WDM evolves to support intelligent, rapid provisioning of large, interconnection capacities. Optics blends in with advanced IC technologies to form an intelligent, opto-electronic metro edge.

1.2.1 WDM Ring Networks for MAN

WDM rings are made with SONET/SDH concepts [8] making time slots within wavelengths and performing optically equivalent channel operations such as add-drop, pass-through, protection, etc. These rings provide very good bandwidth scalability, data transparency, and multiple data rates. Optical bypass removes the need for complicated electronic access to client signals and gives significant cost savings over traditional add–drop multiplexer (ADM)/optical cross-connect (OXC) nodes. WDM ring architectures contribute from simple static setups (i.e., fixed nodes) to advanced sharing schemes (i.e., dynamic nodes). The basic building blocks of an optical WDM are optical ADM (OADM) nodes. Fixed OADMs operate on static or pre-fixed tuned wavelengths used in static rings for static traffic. With increasing customer dynamics, static rings can provide services, but they require complex manual wavelength planning and yield reduced wavelength. Different optical WDM optical rings are mentioned later in this chapter.

Here, re-configurability is one of the key requirements apart from scalability, in dynamic OADM rings having reconfigurable OADMs (ROADMs).

1.2.2 Metro-Edge Technology

The edge technology in a metro network provides an integration of the core inter-office and the client access points [7]. In this direction, WDM with electronic multiplexing access for sub-gigabit line rates is required to collective diverse end-user protocols onto large-granularity optical (WDM) arms in metro-edge technology [9]. Many metro-edge solutions include next-generation SONET/multi-service provisioning and IP routing of packet rings.

Next-Generation SONET/Multi-Service Provisioning Paradigms

Although a hierarchical TDM device has many issues, it plays a significant role in the convergence of data and optical networks at the metro edge [7] because of short-haul SONET/SDH. A large part of it comprises of larger OC-48/STM-16 and OC-192/STM-64 systems, and at the same time, smaller OC-3/STM-1 and OC-12/STM-4 systems are also used for deployments in metro edge [1]. The network having existing routers/switches has SONET/SDH interfaces and requires a broader generic framing protocol (GFP) (for mapping “non-standard” data protocols). There are many reported approaches to enhance SONET/SDH suited to data traffic needs. All these have two main features: efficient data-tributa...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface
• Acknowledgments
• Author
• Chapter 1 Optical Ring Metropolitan Area Networks
• Chapter 2 Queuing System and Its Interconnection with Other Networks
• Chapter 3 Routing and Wavelength Assignment
• Chapter 4 Virtual Topology
• Chapter 5 Wavelength Conversion in WDM Networks
• Chapter 6 Traffic Grooming in Optical Networks
• Chapter 7 Survivability of Optical Networks
• Chapter 8 Restoration Schemes in the Survivability of Optical Networks
• Chapter 9 Network Reliability and Security
• Chapter 10 FTTH Standards, Deployments, and Issues
• Chapter 11 Math Lab Codes for Optical Fiber Communication System
• Index