IP over WDM

Kevin H. LiuQOptics Inc, Oregon, USA

JOHN WILEY & SONS, LTD

Innodata0470855290.jpg

IP over WDM

IP over WDM

Kevin H. LiuQOptics Inc, Oregon, USA

JOHN WILEY & SONS, LTD

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Contents

List of Figures xi

List of Tables xvii

About the Author

Preface xxi

Acknowledgements xxv

1 Introduction 11.1 What is a WDM-enabled Optical Network 1

1.1.1 TDM vs. WDM 21.1.2 WDM Optical Network Evolution 4

1.2 Why IP over WDM 61.3 What is IP over WDM 71.4 Next-generation Internet 111.5 IP/WDM Standardisation 141.6 Summary and Subject Overview 16

2 Review 192.1 Telecommunication Networks 192.2 Optical Communications 21

2.2.1 Optical Communication Impairments 232.2.2 Optical Switching 252.2.3 Opaque vs. Transparent Switching 28

2.3 WDM Network Testbed and Product Comparison 292.3.1 WDM Network Testbeds 292.3.2 Product Comparison 32

2.4 Communication Protocols 322.5 Internet Architecture 352.6 IPv4 Addressing 36

2.6.1 Subnetting 38

xix

2.6.2 Unnumbered Addresses 392.6.3 Secondary Addresses 392.6.4 Classless Inter-Domain Routing (CIDR) 40

2.7 Gigabit Ethernet 402.7.1 Gigabit Ethernet Architecture 422.7.2 Gigabit Ethernet Applications 43

2.8 Multiprotocol Label Switching (MPLS) 442.8.1 Label Distribution 462.8.2 Traffic Engineering 482.8.3 Quality of Service (QoS) 492.8.4 Virtual Private Network (VPN) 51

2.9 Distributed Systems 522.9.1 Design Objectives 532.9.2 Architectural Models 542.9.3 Clustering 552.9.4 API for Distributed Applications 55

3 Characteristics of the Internet and IP Routing 573.1 IP Router Overview 57

3.1.1 IPv4 Datagram 583.1.2 QoS Queuing Models 61

3.2 Internet Traffic Engineering 623.2.1 Shortest Path Routing 623.2.2 Equal Cost Multi-Path (ECMP) 633.2.3 Optimised Multi-Path (OMP) 633.2.4 MPLS OMP 64

3.3 TCP Traffic Policing 643.3.1 TCP Flow Control 653.3.2 TCP Congestion Control 67

3.4 Internet Traffic Characteristics and Models 693.4.1 Internet Traffic Statistics 703.4.2 Traffic Models and Long Range Dependence 79

3.5 Internet Routing 833.6 Open Shortest Path First Protocol (OSPF) 85

3.6.1 OSPF Messages 863.6.2 Link State Advertisement (LSA) 873.6.3 Routing in OSPF 88

3.7 Border Gateway Protocol (BGP) 903.7.1 Internal and External BGP 903.7.2 BGP Messages 913.7.3 Path Attributes 933.7.4 Policy Filtering 943.7.5 BGP Routing 94

3.8 IPv6 95

CONTENTSvi

4 WDM Optical Networks 994.1 Optical Modulation 994.2 Optical Switching Components and Technology 101

4.2.1 Optical Amplifier (OAMP) and Repeater 1014.2.2 Optical Add/Drop Multiplexer (OADM) 1024.2.3 Optical Crossconnect (OXC) 1024.2.4 Transponder 1044.2.5 Switching Fabric 1054.2.6 Optical Switch/Router 111

4.3 WDM NC&M Framework 1134.3.1 TMN Framework 1134.3.2 WDM Network Management and Visualisation Framework 116

4.4 WDM Network Information Model 1194.4.1 WDM Object Model 1204.4.2 An Example of WDM Network and Connection MIB 123

4.5 WDM NC&M Functionality 1264.5.1 Connection Management 1264.5.2 Connection Discovery 1394.5.3 WDM Client Topology Reconfiguration 1404.5.4 Signal Quality Monitoring 1414.5.5 Fault Management 142

4.6 WDM NE Management 1434.6.1 NE MIB 1454.6.2 NE Interfaces 147

4.7 WDM Signalling 1474.7.1 Wavelength Signalling and Routing 1474.7.2 Circuit Switching vs. Just-In-Time (JIT) Burst Switching 148

4.8 WDM DCN 1514.9 WDM Network Views 1524.10 Discussion 154

5 IP over WDM 1555.1 IP over WDM Networking Architectures 155

5.1.1 What is Optical Burst Switching 1565.1.2 What is Optical Packet Switching 1575.1.3 Three IP/WDM Networking Architectures 158

5.2 IP/WDM Internetworking Models 1625.2.1 IP over Reconfigurable WDM 1625.2.2 IP over Switched WDM 166

5.3 IP/WDM Service Models 1695.3.1 Domain Service Model 1695.3.2 Unified Service Model 1715.3.3 Services 171

5.4 Summary 172

CONTENTS vii

6 IP/WDM Network Control 1756.1 IP/WDM Network Addressing 177

6.1.1 Overlay Addressing 1786.1.2 Peer Addressing 180

6.2 Topology Discovery 1816.2.1 OSPF Hello Message 1826.2.2 Link Management Protocol (LMP) 184

6.3 IP/WDM Routing 1876.3.1 Routing Information Base Construction and Maintenance 1876.3.2 Route Computation and WDM Switching Constraints 1896.3.3 OSPF Extensions 1936.3.4 Routing Behaviour 1996.3.5 Routing Scalability 202

6.4 IP/WDM Signalling 2046.4.1 RSVP Overview 2046.4.2 RSVP Extension for Optical Networks 2066.4.3 RSVP Extension Implementation Architecture 2076.4.4 RSVP Message Extensions 2086.4.5 Hybrid Label Allocation Scheme for Optical Networks 2126.4.6 Discussion 214

6.5 WDM Network Access Control 2146.6 GMPLS 216

6.6.1 Discussion 2176.7 IP/WDM Restoration 218

6.7.1 Provisioning Case Study 2216.7.2 Restoration Case Study 222

6.8 Inter-domain Network Control 2236.8.1 IP/WDM Network Reachability vs. Availability 2256.8.2 Inter-domain Routing Information Exchange 226

6.9 WDM Network Element Control and Management Protocol 2326.9.1 Simple Network Management Protocol (SNMP) 2326.9.2 General Switch Management Protocol (GSMP) 2336.9.3 Optical Switch Control Protocol (OSCP) 239

6.10 Summary 2436.10.1 Network Control vs. Network Management 243

7 IP/WDM Traffic Engineering 2457.1 What is IP over WDM Traffic Engineering 2457.2 Modelling of IP over WDM Traffic Engineering 246

7.2.1 Overlay Traffic Engineering 2467.2.2 Integrated Traffic Engineering 2487.2.3 Comparison of the Two Models 248

7.3 IP over WDM Traffic Engineering Functional Framework 2497.3.1 IP/WDM Network State Information Database 2517.3.2 IP to WDM Interface Management 2537.3.3 Examples of Reconfiguration Triggers 253

CONTENTSviii

7.3.4 Traffic Monitoring and Measurements 2547.3.5 Optical Signal Performance Monitoring 260

7.4 Teletraffic Modelling 2617.4.1 Classical Telephone and Data Traffic Model 2617.4.2 Novel Data Traffic Models 2627.4.3 A Bandwidth Projection Model 263

7.5 MPLS Traffic Engineering 2687.5.1 Load Balancing 2687.5.2 Network Provisioning 272

7.6 Lightpath Virtual Topology Reconfiguration 2737.6.1 Regular vs. Irregular Virtual Topology 2747.6.2 Topology Design Problem Formulation 2757.6.3 Heuristic Algorithms 2767.6.4 Virtual Topology Migration 281

7.7 Reconfiguration for Packet Switched WDM Networks 2847.7.1 Packet Switched WDM Reconfiguration Overview 2847.7.2 Reconfiguration Conditions 2867.7.3 A Case Study 2877.7.4 Heuristic Algorithm Description 2887.7.5 Heuristic Discussion 2937.7.6 Lightpath Reconfiguration Migration 294

7.8 Simulation Study of IP over WDM Reconfiguration 2957.8.1 Traffic Generation 2967.8.2 Simulation Results 297

7.9 IP/WDM Traffic Engineering Software Design 3037.9.1 Software Architecture for Overlay Traffic Engineering 3037.9.2 Software Architecture for Integrated Traffic Engineering 3067.9.3 IP Traffic Engineering to Network Control Protocol

(IP TECP) 3077.9.4 IP/WDM User to Network Interface (UNI) 3127.9.5 WDM Traffic Engineering to Network Control Protocol

(WDM TECP) 3187.9.6 IP/WDM Traffic Engineering Tools 326

7.10 Feedback-Based Closed-Loop Traffic Engineering 3277.10.1 Network Topology Implementation Process 3297.10.2 Network Convergence 3307.10.3 A Testbed Study on IP/WDM Traffic Engineering 330

7.11 Summary 334

8 Other IP/WDM Specific Issues 3398.1 IP/WDM Group Communication 339

8.1.1 IP Multicasting 3398.1.2 IP Multicasting in Presence of GMPLS 3418.1.3 IP over WDM Multicasting 342

8.2 IP/WDM Network and Service Management 343

CONTENTS ix

8.2.1 CORBA Reference Model and Telecom Facility 3448.2.2 Connection and Service Management Information

Modelling (CaSMIM) 3488.2.3 Optical Network Service Management 349

8.3 TCP over Optical Networks 350

9 Concluding Remarks 3539.1 Book Summary 3539.2 IP/WDM Network Applications 354

9.2.1 MAN and WAN Network Transport 3549.2.2 Layer 2 or Layer 3 VPN, VLAN, Leased Fibre Line or

Wavelenth Channel 3549.2.3 Optical Interconnect 3559.2.4 Bandwidth Brokers and Traders 356

9.3 Future Research 3569.3.1 Scalable Common Control Plane for Optical Networks 3579.3.2 Next Generation of TCP/IP 3579.3.3 TCP/IP Performance Studies in Presence of a Number

of Parallel Paths and Unidirectional LSPs 3579.3.4 Optical Packet Switching 3589.3.5 Service Protection and Restoration 3589.3.6 Optical Network Applications 3589.3.7 Optical MIB Development 358

Bibliography 359

Web Site List 367

Acronym List 371

Index 381

CONTENTSx

List of Figures

Figure 1.1 TDM vs WDM 2Figure 1.2 WDM-enabled optical networks 3Figure 1.3 WDM network evolution 5Figure 1.4 Transporting IP packets over wavelengths 8Figure 1.5 Three approaches for IP over WDM (data plane) 9Figure 1.6 Data and control traffic in IP and WDM networks 11Figure 1.7 NGI SuperNet testbed (source SuperNet www.ngi-super.org) 12Figure 1.8 NGI SuperNet delayering 13Figure 1.9 Conceptual view of this book 16Figure 2.1 A telecom network 20Figure 2.2 Fibre bandwidth regions with low attenuation for WDM

transmission 22Figure 2.3 Asin(2p ft 1 w ) 22Figure 2.4 A Square Wave (A, f, w ) 23Figure 2.5 Grooming and concatenation 27Figure 2.6 AWDM system as defined in ITU optical transport network layer

model 27Figure 2.7 WDM network testbeds 31Figure 2.8 TCP FSM 34Figure 2.9 Internet architecture 37Figure 2.10 IPv4 class addresses 37Figure 2.11 An example (128.196.0.0) of IP subnetting 38Figure 2.12 IP unnumbered link 39Figure 2.13 Gigabit Ethernet evolution 41Figure 2.14 Ethernet frame format 41Figure 2.15 Gigabit Ethernet protocol architecture 42Figure 2.16 Gigabit Ethernet networks 44Figure 2.17 10 Gigabit Ethernet applications 45Figure 2.18 MPLS header 45Figure 2.19 MPLS concepts 46Figure 2.20 Signalling with RSVP 47Figure 2.21 Constraint-based routing 48Figure 2.22 E-LSP vs L-LSP 50

Figure 2.23 MPLS and BGP 52Figure 2.24 Distributed system service model taxonomy 54Figure 2.25 Socket APIs and high-level APIs 56Figure 3.1 Router functionality 58Figure 3.2 IPv4 datagram format 58Figure 3.3 Fragmentation and reassembly 60Figure 3.4 Router packet queuing 61Figure 3.5 TCP segment header format 65Figure 3.6 TCP flow control 66Figure 3.7 NCREN data network topology 71Figure 3.8 Link NCREN-UNCG traffic statistics 72Figure 3.9 Link NCREN-ECU traffic statistics 73Figure 3.10 Link NCREN-Abilene traffic statistics 75Figure 3.11 Abilene network traffic map (October 2001) 76Figure 3.12 Link Abilene-NYC-Cleveland traffic statistics 77Figure 3.13 Link Abilene-Cleveland-Indianapolis traffic statistics 78Figure 3.14 Link Abilene-Denver-Sunnyvale traffic statistics 79Figure 3.15 Link Abilene-Sunnyvale-Seattle traffic statistics 80Figure 3.16 Internet routing 84Figure 3.17 Routing vs forwarding 84Figure 3.18 OSPF header format 86Figure 3.19 OSPF messages exchange during initialisation 87Figure 3.20 LSA header format 88Figure 3.21 Routing in OSPF 89Figure 3.22 IBGP and EBGP peering 91Figure 3.23 BGP header format 92Figure 3.24 BGP routing flows 95Figure 3.25 IPv6 datagram header format 96Figure 3.26 IPv6 extension header 97Figure 4.1 Optical modulation formats 100Figure 4.2 Optical modulation methods 100Figure 4.3 Erbium-Doped Fibre Amplifier (EDFA) 102Figure 4.4 OADM 103Figure 4.5 OXC 104Figure 4.6 Optical transponder 105Figure 4.7 Switching fabric taxonomy 105Figure 4.8 Grooming/Non-Grooming opaque fabric 107Figure 4.9 MEMS technology (source Lucent) 108Figure 4.10 Bubble switch (source Agilent) 109Figure 4.11 Thermo-Optical switch (source NTT Electronics Corporation) 110Figure 4.12 TMN logical model hierarchy 114Figure 4.13 TMN function blocks (Functional Architecture) 115Figure 4.14 An example of WDM optical network 117Figure 4.15 WDM NC&M system architecture framework 118Figure 4.16 A Point-Multipoint trail in a WDM layer network 119Figure 4.17 An object model for WDM optical network management 121

LIST OF FIGURESxii

Figure 4.18 Sample network and connection example 124Figure 4.19 Network-Level MIB for sample network 124Figure 4.20 Network-Level resource and connection information base for

sample network 125Figure 4.21 WDM information model browser and link configuration

(source MONET NC&M) 126Figure 4.22 WDM wavelength routing 129Figure 4.23 WDM node colouring 132Figure 4.24 Connection request (source MONET NC&M) 134Figure 4.25 Wavelength scheduling 135Figure 4.26 Reconfiguration in WDM network 141Figure 4.27 Wavelength SNR and power monitoring and threshold setting

(source MONET NC&M) 142Figure 4.28 Software architecture of management agent 144Figure 4.29 NE fabric view (source MONET NC&M) 145Figure 4.30 Optical circuit switching vs Just-In-Time switching 148Figure 4.31 Circuit vs Just-In-Time signalling process 149Figure 4.32 MONET DCN Subsystem 150Figure 4.33 MONET NC&M GUI (source MONET NC&M) 152Figure 4.34 Connection route view (source MONET NC&M) 153Figure 5.1 Optical burst switching 156Figure 5.2 Optical packet switching 158Figure 5.3 IP over point-to-point WDM 159Figure 5.4 IP over reconfigurable WDM 160Figure 5.5 IP over switched WDM 161Figure 5.6 NMS overlay control model 163Figure 5.7 UNI overlay control model 164Figure 5.8 Augmented control model 165Figure 5.9 Peer control model 166Figure 5.10 IP over OLSR 167Figure 5.11 IP over OPR 169Figure 5.12 IP/WDM service model 170Figure 6.1 IP/WDM network control and traffic engineering 176Figure 6.2 Software architecture for network control 177Figure 6.3 IP layer addressing in an IP over reconfigurable WDM network 179Figure 6.4 WDM layer addressing 180Figure 6.5 OSPF hello message format 183Figure 6.6 LMP header format 185Figure 6.7 LMP hello message format 186Figure 6.8 OSPF reliable flooding 188Figure 6.9 Dynamic Routing and Wavelength Assignment 199Figure 6.10 Network control process interactions 194Figure 6.11 Opaque LSA header format 194Figure 6.12 Capacity opaque LSA payload 195Figure 6.13 Connection opaque LSA payload 197Figure 6.14 Optical traffic engineering NE opaque LSA payload 198

LIST OF FIGURES xiii

Figure 6.15 Optical traffic engineering link opaque LSA payload 199Figure 6.16 Routing loops 200Figure 6.17 Routing oscillation 201Figure 6.18 Routing scalability 203Figure 6.19 RSVP tunneling 206Figure 6.20 An example WDM network for optical RSVP 207Figure 6.21 RSVP software architecture 208Figure 6.22 PATH message label request object format 209Figure 6.23 PATH message label request object format for explicit path

setup and local wavelength assignment 210Figure 6.24 RESV message label object format 211Figure 6.25 Hybrid label allocation scheme 213Figure 6.26 A WDM metropolitan area network 215Figure 6.27 Packet to wavelength mapping function 215Figure 6.28 GMPLS hierarchy 216Figure 6.29 IP/WDM restoration 218Figure 6.30 Lightpath protection vs link protection 221Figure 6.31 Subnet segment restoration vs network restoration 222Figure 6.32 IP/WDM inter-domain network control 224Figure 6.33 GSMP adjacency protocol message format 235Figure 6.34 GSMP Request-Response message format 236Figure 6.35 Process flow for GSMP QoS model 239Figure 7.1 IP/WDM traffic engineering (TE) 246Figure 7.2 Overlay traffic engineering 247Figure 7.3 Integrated traffic engineering 248Figure 7.4 IP/WDM traffic engineering functional framework 250Figure 7.5 Reconfiguration in IP/WDM networks 254Figure 7.6 The ‘fish’ problem 269Figure 7.7 OSPF-OMP 271Figure 7.8 MPLS-OMP 271Figure 7.9 Virtual topology design and routing 273Figure 7.10 Packet switched WDM network reconfiguration 285Figure 7.11 Using lightpath reconfiguration to accommodate more LSPs 287Figure 7.12 An example where an extended heuristic algorithm can be

applied 291Figure 7.13 LSP healing after lightpath break 295Figure 7.14 Simulation topology (i.e. the fixed topology) and topology

design examples using heuristic algorithms for the trafficpattern shown in Table 7.2 296

Figure 7.15 Normalised network throughput comparison for differentnetworks under a number of traffic patterns 297

Figure 7.16 Weighted hop-distance comparison for different networksunder a number of traffic patterns 299

Figure 7.17 Traffic patterns with different skewness 299Figure 7.18 Network throughput gain (NTG) and average weighted hop

LIST OF FIGURESxiv

distance gain (AWHG) using shortest path routing; every pointplotted using the average over 100 trails 301

Figure 7.19 Network throughput gain (NTG) and average weightedhop-distance gain (AWHG) using equal cost multi-pathrouting; every point plotted using the average over 100 trails 302

Figure 7.20 Software architecture for overlay traffic engineering in IP/WDMnetworks 304

Figure 7.21 Software architecture for integrated traffic engineering in IP/WDM networks 306

Figure 7.22 Traffic engineering modules and interactions for the IP layer 308Figure 7.23 TECP common header format 309Figure 7.24 Message format for inventory response messages 310Figure 7.25 Message format for traffic statistics request messages 311Figure 7.26 Message format for traffic statistics response messages 312Figure 7.27 Message format for current virtual connection status response

messages 313Figure 7.28 IP/WDM UNI message format 314Figure 7.29 Message format for create and update trail request messages 320Figure 7.30 Message format for explicit route trail request messages 322Figure 7.31 Message format for trail response messages 323Figure 7.32 Message format for event notification messages 324Figure 7.33 Example of traffic engineering tools GUI 327Figure 7.34 A feedback control system in control engineering 328Figure 7.35 Feedback-based closed-loop network traffic engineering 328Figure 7.36 An IP over reconfigurable WDM network testbed 331Figure 7.37 Testbed experimentation workflows 332Figure 7.38 A feedback-based closed-loop traffic engineering experiment 333Figure 8.1 IP unicasting vs multicasting 340Figure 8.2 IP multicasting with LSPs 341Figure 8.3 Multicasting for a data-plane overlay IP/WDM network 342Figure 8.4 MTNM NMS-EMS architecture 344Figure 8.5 CORBA reference model 345Figure 8.6 Telecom notification service 345Figure 8.7 Telecom log service 347Figure 8.8 CaSMIM interface layout 349Figure 8.9 TCP over buffered conventional IP networks 351Figure 8.10 TCP over IP/WDM networks 352Figure 9.1 WDM WAN and MAN 355

LIST OF FIGURES xv

List of Tables

Table 1.1 IETF sub-IP workgroups 14Table 2.1 Circuit, packet, and cell switching 21Table 2.2 Opaque vs. transparent switching 28Table 2.3 WDM network testbed comparison 32Table 2.4 WDM product comparison 33Table 2.5 TCP/IP vs. OSI model 35Table 3.1 Protocol field encoding 60Table 3.2 Common path attributes 93Table 4.1 Switching fabric comparison 112Table 5.1 WDM networking technology comparisons 155Table 7.1 T.E. models implementation 249Table 7.2 A typical traffic pattern 298Table 7.3 IP/WDM access control mapping table 326Table 7.4 Reconfiguration time over the IP/WDM testbed 333

About the Author

Kevin H. Liu, Ph.D., is a lead software architect at QOptics, currently working onscalable common control plane for optical networks. He was a research scientist atInternet Architecture Research Lab, Telcordia Technologies (formerly Bell Commu-nications Research or Bellcore). Before joining Bellcore, he held research and teach-ing positions at Rutgers University, New Brunswick, New Jersey, and VictoriaUniversity of Technology, Melbourne, Victoria, Australia. He has worked on severalU.S. government DARPA-funded IP/WDM research projects such as the MONET(Multiwavelength Optical Networking) NC&M (Network Control and Management)project, the NGI (Next Generation Internet) SuperNet NC&M project, and the NGIOptical Label Switching project.He has published over thirty journal and conference papers in the areas of network

control and management, WDM optical networks, and distributed systems, andapplied patent in IP/WDM networks. Among the publications, his articles haveappeared in IEEE Transactions on Communications, IEEE Journal on Selected Areasin Communications, IEEE Journal of Lightwave Technology, IEEE Network Magazine,and IEICE Transactions on Communications.His biography has been included in the‘‘Who’s Who in the World’’ and the ‘‘International Who’s Who of Information Tech-nology’’.The author can be reached by email at kliu@ieee.org.

Preface

It is widely believed that Internet Protocol (IP) provides the only convergence layer inthe global and ubiquitous Internet. Above the IP layer, there are a great variety of IP-based services and appliances that are still evolving from its infancy. The inevitabledominance of IP traffic makes it apparent that the engineering practices of thenetwork infrastructure should be optimised for IP. On the other hand, fibre opticsas a dispersive technology revolutionises the telecom and networking industry byoffering enormous network capacity to sustain next-generation Internet growth.WDM (Wavelength Division Multiplexing) as a fibre bandwidth exploring technol-ogy is state-of-the-art. UsingWDM over existing fibre networks can increase networkbandwidth significantly as well as maintain the same network operational footprint. Ithas been proved as a cost-efficient solution for long-haul networks.As worldwide deployment of optical fibres and WDM technologies such as WDM

components and control systems mature, WDM-based optical networks have beendeployed not only in backbones but also in metro, regional, and access networks.WDM optical networks are no longer just point-to-point pipes providing physicaltransport services, but blend with a new level of network flexibility. Integrating IPandWDM to transport IP traffic over WDM-enabled optical networks efficiently andeffectively becomes an urgent yet important task. As the WDM and IP over WDMindustries emerge and grow, related industry forums have been established, such asOIF and ODSI, and a sub-IPArea including sevenworking groups has been formed inIETF, focusing on standardisation and IP/WDM inter-networking.To our knowledge, this book is the first to focus on IP over WDM optical networks

with in-depth discussion on IP/WDM network control and IP/WDM traffic engineer-ing. It not only summarises the fundamental mechanisms and the recent develop-ment and deployment of WDM optical networks but also details both the networkand the software architecture to implement WDM-enabled optical networksdesigned to transport IP traffic.The book is targeted for the following audiences:

† Technical engineers and network practitioners, network designers and analysts,network managers and technical management personnel interested in the recentdevelopment, implementation, and deployment of IP/WDM networks.

† First-year graduate students or senior undergraduate students majoring innetworking and/or network control and management.

A modest background is required to understand the material presented in thisbook. The reader is expected to have a basic understanding of computer networksand computer systems. Example introductory materials can be found in ComputerNetwork [Tane96], Computer Architecture [Tane99], and Operating Systems[Nutt02].IP/WDM networking is designed for transporting IP traffic in a WDM-enabled

optical network, to leverage IP universal connectivity and the WDM massive band-width capacity. This book answers the following questions:

† What is a WDM network?† What is IP over WDM?† Why IP over WDM?† What is the recent (research and commercial) development on WDM optical

networks?† How to interconnect and/or inter-network IP and WDM?† How to control and manage IP/WDM networks?† What is IP/WDM traffic engineering?† What are the benefits of virtual topology reconfiguration?† What are the IP/WDM network applications?† What are the other specific issues related to IP/WDM networks?As communication and computer networks are quickly converging, the conven-

tional Telecom and IP network equipment, their control and management software,and their services and applications will inevitably interact and eventually integrate tosupport both data and voice traffic. On the one hand, the conventional telecomnetworks developed three switching modes: circuit switching such as the T1 trans-port network, packet switching such as X.25 and frame relay, and cell switching suchas ATM, and developed and deployed the control software such as SS7 for physicalcircuits and UNI, NNI, and PNNI for ATM virtual circuits. On the other hand, IPnetworks become widespread and captured nearly all the data traffic market due tothe popularity and the emergence of the Internet. IP follows a packet switchingparadigm, and with MPLS, IP can support different qualities of service. IP controlprotocols are widely accepted, deployed, and proved to be scalable.In a previous computer and communication networking integration attempt, IP

and ATM were connected. A classical IP over ATM approach forms a static clientserver networking system, where IP plays the role as the client network and ATMworks as the server transport network. This approach is complex since both IP andATM have complete network control and management systems such as routing andsignalling protocols. The IP network and the ATM network use different addressing sothey cannot interact with each other directly. As a result, address resolution betweenIPand ATM has to be provided. The classical IP over ATM approach is static and doesnot scale.To some extent, WDM networks can be treated as ATM networks with parallel

transmission technology. An ATM switch has fibre ports whereas a WDM switch haswavelength ports (multiple wavelength channels per fibre). In addition, a WDMswitch can be implemented in pure optical domain so that the latency is kept verylow. IP over WDM is the topic of this book. We present several IP/WDM networking

PREFACExxii

models such as overlay, augmented, or peer-to-peer. The selection for implementa-tion also depends on network ownership and administration authority. We willpresent IP/WDM traffic engineering for optimal resource allocation in IP/WDMnetworks.The book reviews the IP/WDM history as well as the international effort on the

next-generation Internet. It also surveys the current IP/WDM standardisation. Adetailed review on IP/WDM background information is provided. To assist the readerto understand the challenge posed in transporting IP traffic over WDM, we willpresent a chapter on the characteristics of the Internet and the IP routing (Chapter3), and a chapter on WDM optical networks (Chapter 4). Topics on IP/WDM areorganised into four chapters: IP over WDM internetworking models (Chapter 5), IP/WDM network control (Chapter 6), IP/WDM traffic engineering (Chapter 7), and IP/WDM specific issues (Chapter 8).

Kevin LiuNew Jersey

PREFACE xxiii

Acknowledgements

Writing this book has been an interesting experience in my life. I would like to thankall the people around me. In particular, I would like to thank my colleagues atBellcore/Telcordia. The information in this book originates from several projects:the MONET NC&M project, the NGI SuperNet NC&M project, and the NGI OLSproject.Some of the material in the book has appeared in my early publications [Liu00a],

[Liu00b], and [Liu02]. I would like to thank the coauthors of these papers in parti-cular Dr John Wei, Brian Wilson, and Dr Changdong Liu. I also would like to thankIEEE for generously assigning me the right and the publisher to use these publicationsin this book.I would like to thank the members of the MONET NC&M team in particular

Dr John Wei, Brian Wilson, Jorge Pastor, Dr Ned Stoffel, Dr Mike Post, Dr TsanchiLi, and Kenneth Walsh for many stimulating discussions. I also would like to thankcolleagues at the government agencies (DARPA, DIA, DISA, NASA, NRL, and NSA)for their help, support, and feedback during the course of the MONET NC&Mwork. Iwould like to thank DARPAMONET ProgramManager, Dr Burt Hui, for his guidanceand support.I would like to thank the members of the NGI SuperNet NC&M team in particular

Dr Yukun Tsai, Dr Narayanan Natarajan, Dr Tsong-Ho Wu, Dr Changdong Liu,Dr Ramu S. Ramamurthy, and Arunendu Roy. I would like to thank the membersof the NGI OLS team in particular Dr Gee-Kung Chang, Dr Sung-Yong Park, BrianMeagher, Jeffery Young, and Dr George Ellinas. I would like to thank DARPA NGIProgramManager, Dr Mari Maeda, for her guidance and support during the course ofthe NGI projects.I would like to thank the editors at John Wiley & Sons, Ltd for their help and

support, and the reviewers of my book draft and the book proposal for valuablesuggestions.Finally, I would like to thank my family especially my wife, Guohua, for her love,

encouragement, and support throughout the writing of this book.

1Introduction

† What is a WDM-enabled optical network?† Why IP over WDM?† What is IP over WDM?† Next-generation Internet† IP/WDM standardisation† Summary and subject overview

1.1 What is a WDM-enabled Optical Network?

Conventional copper cables can only provide a bandwidth of 100 Mbps (106) over a1 Km distance before signal regeneration is required. In contrast, an optical fibreusing wavelength division multiplexing (WDM) technology can support a number ofwavelength channels, each of which can support a connection rate of 10 Gbps (109).Long-reach WDM transmitters and receivers can deliver good quality optical signalswithout regeneration over a distance of several tens of kilometres. Hence, opticalfibre can easily offer bandwidths of tens of Tbps (1012). (Note throughout the book weuse ‘b’ for bits and ‘B’ for bytes.) In addition to high bandwidth, fibre, made of glass(which is in turn made mainly from silica sand), is cheaper than other conventionaltransmission mediums such as coaxial cables.Glass fibre transmission has low attenuation. Fibre also has the advantage of not

being affected by electromagnetic interference and power surges or failures. In termsof installation, fibre is thin and lightweight, so it is easy to operate. An existingcopper-based transmission infrastructure can be (and has been) replaced with fibrecables. In the fibre infrastructure, WDM is considered as a parallel transmissiontechnology to exploit the fibre bandwidth using non-overlapping wavelength chan-nels.An individual optical transmission system consists of three components:

† the optical transmitter† the transmission medium† the optical receiver.

The transmitter uses a pulse of light to indicate the ‘1’ bit and the absence of light torepresent the ‘0’ bit. The receiver can generate an electrical pulse once light isdetected. A single-mode fibre transmission requires the light to propagate in a straightline along the centre of the fibre. The use of single-mode fibre results in a goodquality signal, so it is used for long-distance transmission.A light ray may enter the fibre at a particular angle and go through the fibre through

internal reflections. A fibre with this property is known as multimode fibre. The basicoptical transmission system is used in an optical network, which can be a localaccess network (LAN), a metropolitan local exchange network (MAN), or a long-haul inter-exchange network (also known as Wide Area Network, WAN).

1.1.1 TDM vs. WDM

There is a continuous demand for bandwidth in the construction of the Internet. It isalso relatively expensive to lay new fibres and furthermore to maintain them. Toexplore the existing fibre bandwidth, two multiplexing techniques have been devel-oped as shown in Figure 1.1.

Time Division Multiplexing (TDM) is achieved through multiplexing many lowerspeed data streams into a higher speed stream at a higher bit rate by means of non-overlapping time slots allocated to the original data streams.Wavelength Division Multiplexing (WDM) is used to transmit data simultaneously

at multiple carrier wavelengths through a single fibre, which is analogous to usingFrequency DivisionMultiplexing (FDM) to carry multiple radio and TV channels overair or cable. We focus our discussion on WDM optical networks since TDM tech-nology requires extremely high-speed electronics for high-speed data transmissionand commercial high-speed TDM development lags far behind WDM. However,TDM andWDM can be used together in such a way that TDM provides time-sharingof a wavelength channel, for example, through aggregating access network traffic forbackbone network transport.

INTRODUCTION2

Figure 1.1 TDM vs. WDM.