A comprehensive introduction to optical networking: current solutions and emerging breakthroughs.
In Optical Networks: Third Generation Transport Systems, leading telecom consultant Uyless Black presents an authoritative introduction to the emerging technologies that will drive the next communications revolution. From MPLS to Optical-over-IP to the new Optical Link Management Protocol (OLMP), Black's expert explanations and practical insight will be invaluable to every professional building, deploying, or managing optical networks. Engineers new to the field will especially appreciate his review of current fiber systems, signaling, SONET/SDH standards, and how these technologies lay the foundation for tomorrow's 3G advances.
Optical Networks: Third Generation Transport Systems is the first book to cover every key optical technology for building networks of unprecedented power, flexibility, and manageability.
Three Generations of Digital Transport Networks. All Features Are Not Yet Available. Optical Fiber Capacity. A Brief Introduction to WDM and TDM. Combining WDM and TDM. The Optical Marketplace. The Local Loop Bottleneck Must Be Solved. Expansion of Network Capacity. Wireless Optical Systems. Key Optical Nodes. Key Terms for the Cross-connect. Other Key Terms. Another Look at the Optical Node. Evolution of Optical Systems. Key Attributes of Optical Fiber. Summary.
The Local Connections. The Backbone Connections. The Digital Multiplexing Hierarchy. The Digital Signaling Hierarchies. T1 or DS1; T3 or DS3? The Layered Protocol Model in the Transport Network. Considerations for Interworking Layer 1, Layer 2, and Layer 3 Networks. Summary.
The Basics. The Wavelength. The Basic Components. The Source of the Signal. The Detector. Structure of the Fiber. Angles. Fiber Types. Key Performance Properties of Fiber. Attenuation. Amplifier Spontaneous Emission (ASE). Chromatic Dispersion. Polarization-mode Dispersion (PMD). Lasers. Summary.
Timing and Synchronization in Digital Networks. Effect of a Timing Error. The Clocking Signal. Types of Timing in Networks. The Synchronous Clock Hierarchy. Timing Variations. Frequency Accuracy. Methods of Clock Exchange. Free-Running. Line-Timed. Loop-Timed. External. Through-Timed. Distribution of Timing Using SONET and DS1. Timing Downstream Devices. The Building Integrated Timing Supply (BITS). Synchronization Status Messages (SSMs) and Timing Loops. Summary.
How SONET and SDH Came into Being. Participation by ITU-T. Reasons for Success of SONET/SDH. The SONET Multiplexing Hierarchy. SONET and SDH Multiplexing Structure. The SONET/SDH Frame Structure. Rationale for the 51.840 Mbit/s Envelope. Overhead and User Areas in the Envelope. SONET and SDH Functional Components. SONET and SDH Problem Detection. Locating and Adjusting Payload with Pointers. Virtual Tributaries in More Detail. Virtual Tributaries and Virtual Containers. The Overhead Bytes. SONET and SDH Concatenation. Summary.
The Digital Wrapper. Control Planes. In-band and Out-of-band Control Signaling. An In-band Signal on an O/O/O PXC. Importance of Multiplexing and Multiplexing Hierarchies. Current Digital Transport Hierarchy. SONET Multiplexing Hierarchy. SDH Multiplexing Hierarchy. Revised SDH Transport Hierarchy. Key Indexes and Other Terms. The New Optical Transport and Digital Transport Hierarchy. ODUk Mapping and Multiplexing. The OTN Layered Model. Another View. Full Functionality Stack: OTM-n.m. Reduced Functionality Stack: OTM-nr.m and OTM-0.r. Encapsulation and Decapsulation Operations. Generic Framing Procedure (GFP). Summary.
The WDM Operation. Dense Wave Division Multiplexing (DWDM). TDM and WDM Topologies. Relationship of WDM to SONET/SDH. Erbium-doped Fiber (EDF). WDM Amplifiers. Gain Flatness. Add-Drop Multiplexers. WADM Input and Output Ports. WDM Cross-connects. Wavelength Continuity Property. Example of DWDM Wavelength Plan. Average Versus Maximum Span Loss and Chromatic Dispersion. Higher Dispersion for DWDM. Tunable DWDM Lasers. Summary.
The Non-negotiable Requirement: Robust Networks. Diversity in the Network: Which Control Plane? Line and Path Protection Switching. Types of Topologies. Working and Protection Fibers. Point-to-Point Topology. 1:N Protection Channel Sharing. Optical Channel Concatenation. Bi-directional Line-Switched Ring (BLSR). Protection Switching on Four-Fiber BLSR. Meshed Topologies. Passive Optical Networks (PONs). Optical Ethernets and Ethernet PONs. Ethernet in the Wide Area Backbone? Metro Optical Networking. Summary.
What IS Label Switching? Reasons for Using Label Switching. The Forwarding Equivalence Class (FEC). Scalability and Granularity: Labels and Wavelengths. Types of MPLS Nodes. Label Distribution and Binding. Methods for Label Distribution. Label Swapping and Traffic Forwarding. MPLS Support of Virtual Private Networks (VPNs). MPLS Traffic Engineering (TE). Traffic Oriented or Resource Oriented Performance. Traffic Trunks, Traffic Flows, and Label Switched Paths. LDP, CR-LDP, RSVP-TE, and OSPF (Extensions) for TE Support. Multiprotocol Lambda Switching (MPlS). Relationships of OXC and MPLS Operations. MPLS and Optical Wavelength Correlation. Failure of the Optical Connection. MPLS and Optical TE Similarities. Possibilities for the MPlS Network. Control and Data Planes Interworking. Summary.
IP, MPLS, and Optical Control Planes. The Internet Control and Data Planes. The MPLS Control and Data Planes. The Optical Control and Data Planes. Interworking the Three Control Planes. Management of the Planes. Diverse Views on Control Planes' Interworkings. A Framework for IP over Optical Networks. Two General Models. Domain Services Model. Unified Service Model. Interconnections for IP over Optical. An Opposing View. Which Approaches to Use? Generalized MPLS (GMPLS) Use in Optical Networks. Considerations for Interworking Layer 1 Lambdas and Layer 2 Labels. Examples of GMPLS Operations. Suggested Labels for the Wavelengths. Bi-directional LSPs in Optical Networks. Link Protection. The Next Horizon: GMPLS Extensions for G.709. Technology Independent Part. Technology Dependent Part. OTM Overhead Signal (OOS). Transparency. G.709 Label Space. OCh Label Space. Applications. ODUk General Communication Channel (GCC). A More Immediate Horizon: GMPLS with SONET and SDH. Traffic Parameters. Summary.
Keep the Optical Link Up and Running. What is Managed. Data-bearing Links. Clarification of Terms. Basic Functions of LMP. LMP Messages. LMP Message Header. LMP TLVs. The Fields in the LMP Messages. Control Channel Management. Parameter Negotiation. The Hello Protocol. Link Property Correlation. Link Connectivity Verification. Fault Management. Extending LMP Operations for Optical Link Systems (OLSs). Link Summarization. Fault Management. Trace Monitoring. Summary.
The State of the Art in Optical Switching. Order of Preferences in Switching Implementations. Clarification of Key Terms. One Aftermath of September 11: Increasing Load on the Transport Networks. Evolution of Switching Technologies. The Speeds of Electronics and Photonics. An Optical Router. The Control Element. Optical Switching Technologies. Optical Resources. MicroElectroMechanical Systems (MEMS). Protecting the Label Switched Path. Protection of the Optical Switched Path (OSP). Correlating the Wavelength OSP with the MPLS LSP. Setting up the OSPs and LSPs Between Nodes H, I, and J. Setting Up a Protection Path Between Nodes H, G, and J. Recovery and Use of Protection Path. Expanding the Roles of Nodes G and I. Nesting the LSPs and OSPs. Topology Choices for a Node Failure. Plane Coupling and De-coupling. Some End-to-End Wavelengths and Some Node-to-Node Wavelengths. Granularity of Labels vs. Wavelength Support. Approach to the Problem of LSP and OSP Interworking. MEMS and Optical Switching Re-examined. Thermo-optic Switches. Bubble Switches. Summary.
Objectives of the ASON. The UNI and the NNI. Managing the Optical Bandwidth in the ASON. The General Approach to Optical Bandwidth Management. IETF Optical Carrier Framework for the UNI. Focus on OC-48/STM-16 and Above. UNI-SR (Subrates). Types of Connections. Connection Attributes. Identification Attributes. Connection Characteristic Attributes. Routing Constraints Attributes. The Network-to-Network Interface (NNI). NNI Signaling Requirements. Neighbor Discovery. NNI Topology and Resource Distribution Protocol. NNI Protocol Mechanisms. UNI and NNI Signaling Services. Summary.
IP over ATM over SONET. The OSI and Internet Layered Models. Placement of Core Protocols. PPP and L2TP. ATM in the SONET/SDH Payload Envelope. PPP in the SONET Payload Envelope. Prevalent Approach in Today's Internets. Encapsulation/Framing Rules. ATM and Frame Relay Framing Formats. Encapsulation Field Values. Encapsulation Options with SNAP. The PPP Packet. The ATM vs. IP Debate. Overhead of IP and ATM. Is the ATM Overhead Tolerable? Three Encapsulation Methods. Method 1: Conventional Approach. Method 2: Lightweight PPP. Method 3: Eliminating ATM. Summary.
Migration to IP Optical Networking. IP and the Optical Backbone. Example of IP and l Forwarding. IP Subnets. Support of Non-optical Nodes. Placing MPLS into the Picture. Putting It Together. IP Routing Table. MPLS Cross-connect Table: Interface A. Optical Cross-connect Table: Interface A. Optical Cross-connect Table: Interface B.
This book describes third generation digital carrier transport networks. The primary focus of the book is on the role of optical fiber and optical routers in these networks, with the emphasis on wave division multiplexing (WDM). Third generation transport networks also entail considerable interworking with Multiprotocol Label Switching (MPLS), and this topic is covered in several chapters. As well, the ITU and the IETF are defining new multiplexing hierarchies for the third generation transport network, and these efforts are described in this book.
You might be wondering what are first and second generation transport networks? I classify first generation systems, introduced in the 1960s, as those that were/are built with predominately T1 and E1 architectures. I classify second generation systems, introduced in the 1980s, as those that were/are built with SONET and SDH architectures. Although these topics are covered in this book, the emphasis is on networks that go beyond these older technologies.
The emphasis of this book is on newer technologies, being introduced as you read this preface, with the focus on optical internets: those dealing with IP over optical; label switching with WDM; optical cross-connects; optical routers; optical bandwidth on demand; and the emerging Optical Transport Network (OTN), published by ITU-T and amplified by the IETF. For the newcomer, Chapter 3 provides tutorials on the basics of optical technology, including the operations of optical fiber and lasers.
I want to emphasize that this book has only one chapter on the technology of optical fiber itself. Scores of books are available on this subject, and my intent is to move beyond the descriptions of a light signal on a fiber. I think Chapter 3 will be sufficient for the newcomer on the subject of optical fiber, and I provide you with some excellent references if you wish to delve into more details about the subject.Internet Drafts: Work In Progess
A considerable portion of this book is devoted to explaining many Internet-based specifications pertaining to IP-based optical networks.
Keep in mind that the Internet drafts are works in progress, and should be viewed as such. You should not use the drafts with the expectation that they will not change. Notwithstanding, if used as general tutorials, the drafts discussed in this book are "final enough" to warrant their explanations. Indeed, many of my clients use these drafts in their product planning and design.
For all the Internet standards and drafts the following applies:
Copyright © The Internet Society (1998). All Rights Reserved.
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