DAVID MCDYSAN DAVE PAW

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DAVID MCDYSAN DAVE PAW

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iii

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The Accelerating Bandwidth Principle . . . . 21

Worldwide Cooperation for Standards . . . . 22

Review . . . . 24

▼ ³ ATM- and MPLS-Related Standards Bodies . . . . 25

ATM- and MPLS-Related Standards Bodies . . . . 26

International Telecommunications Union (ITU) . . . . 27

ATM Forum . . . . 27

Internet Engineering Task Force (IETF) . . . . 28

Frame Relay Forum . . . . 29

MPLS Forum . . . . 29

DSL Forum . . . . 30

Other B-ISDN/ATM Standards Bodies . . . . 30

Creating Standards: The Players . . . . 30

Vendors . . . . 30

Users . . . . 31

Network Service Providers . . . . 31

Creating Standards: The Process . . . . 32

Charter and Work Plan . . . . 33

Meetings and Contributions . . . . 33

Drafting and Review . . . . 33

Approval and Consensus . . . . 34

User Acceptance and Interoperability . . . . 34

Other Aspects of Standards . . . . 35

Business and Politics . . . . 35

Measures of Success and Proven Approaches . . . . 35

Predicting the Future of Standardization . . . . 36

Review . . . . 36

Part II Networking and Protocol Fundamentals ▼ ⁴ Networks, Circuits, Multiplexing, and Switching . . . . 39

General Network Topologies . . . . 40

Point-to-Point . . . . 41

Multipoint and Broadcast . . . . 42

Star . . . . 44

Ring . . . . 45

Mesh . . . . 46

Data Communications and Private Lines . . . . 47

Simplex, Half-Duplex, and Full-Duplex Transmission . . . . 47

DTE-to-DCE Connections . . . . 48

Private Lines . . . . 50

Data Transmission Methods . . . . 50

Asynchronous and Synchronous Data Transmission . . . . 51

Asynchronous Versus Synchronous Transfer Modes . . . . 52

Principles of Multiplexing and Switching . . . . 53

Multiplexing Methods Summarized . . . . 54

Space Division Multiplexing (SDM) . . . . 54

Frequency Division Multiplexing (FDM) . . . . 54

Time Division Multiplexing (TDM) . . . . 55

Address or Label Multiplexing . . . . 55

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ATM & MPLS Theory & Application: Foundations of Multi-Service Networking

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Examples of Multiplexing . . . . 57

Examples of Switching . . . . 62

Review . . . . 67

▼ ⁵ Basic Protocol Concepts . . . . 69

A Brief History of Packet Switching . . . . 70

Early Reasons for Packet Switching . . . . 71

Principles of Packet Switching . . . . 71

Darwin’s Theory and Packet-Switching Evolution . . . . 73

Basic Protocol Layering Concepts . . . . 75

Open Systems Interconnection Reference Model . . . . 77

Layers of the OSI Reference Model . . . . 81

Physical Layer . . . . 81

Data Link Layer . . . . 82

Network Layer . . . . 83

Transport Layer . . . . 83

Session Layer . . . . 84

Presentation Layer . . . . 84

Application Layer . . . . 84

Mapping of Generic Devices to OSI Layers . . . . 84

Layered Data Communication Architectures . . . . 85

Internet Protocol (IP) Architecture . . . . 85

IBM’s Systems Network Architecture (SNA) . . . . 86

IEEE 802.X Series (LAN/MAN/WAN) . . . . 87

Integrated Services Digital Network Protocol Architecture . . . . 89

Network Service Paradigms . . . . 91

Connection-Oriented Network Service (CONS) . . . . 91

Connectionless Network Services (CLNS) . . . . 92

Connection-Oriented Versus Connectionless Services Analogy . . . . 94

Review . . . . 94

▼ ⁶ Time Division Multiplexing and the Narrowband Integrated Services Digital Network 95 Circuit Switching . . . . 96

History of Circuit Switching . . . . 96

Digitized Voice Transmission and Switching . . . . 97

Digital Data Circuit Switching . . . . 98

Private-Line Networks . . . . 100

Private (Leased)–Line Characteristics . . . . 100

Private-Line Networking . . . . 100

Permanent Versus Switched Circuits . . . . 103

Digital Time Division Multiplexing (TDM) . . . . 104

Plesiochronous Digital Hierarchy (PDH) . . . . 104

SONET and the Synchronous Digital Hierarchy (SDH) . . . . 106

Basic SONET Frame Format . . . . 110

Basics and History of Narrowband ISDN (N-ISDN) . . . . 113

Narrowband ISDN Basics . . . . 113

BRI and PRI Service and Protocol Structures . . . . 115

ISDN D-Channel Signaling . . . . 117

Review . . . . 119

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▼ ⁷ Connection-Oriented Protocols—X.25 and Frame Relay . . . . 121

Packet Switching . . . . 122

Origins of X.25 . . . . 122

Protocol Structure . . . . 123

Networking Context . . . . 124

SDLC, HDLC, and X.25’s Link Layer Protocol . . . . 125

Packet Layer Format and Protocol . . . . 131

Control Functions . . . . 133

Example of X.25 Operation . . . . 133

Traffic and Congestion Control Aspects of X.25 . . . . 135

Service Aspects of X.25 . . . . 137

Frame Relay—Overview and User Plane . . . . 137

Origins of Frame Relay . . . . 137

Frame Relay Protocol Structure . . . . 138

Frame Relay Networking Context . . . . 139

Frame Format . . . . 140

Frame Relay Functions . . . . 142

Example of Frame Relay Operation . . . . 143

Traffic and Congestion Control Aspects of Frame Relay . . . . 144

Service Aspects of Frame Relay . . . . 147

Frame Relay—Control Plane . . . . 149

Frame Relay Control Protocol Networking Context . . . . 149

Frame Relay Standards and Specifications . . . . 150

Frame Relay PVC Status Signaling . . . . 152

Frame Relay PVC Status Signaling Example . . . . 155

Multilink Frame Relay . . . . 157

Frame Relay Service Level Agreements (SLAs) . . . . 159

Frame Relay Operations, Administration, and Maintenance . . . . 161

Frame Relay Fragmentation and Compression . . . . 164

Frame Relay Privacy . . . . 166

Frame Relay Switched Virtual Connections (SVCs) . . . . 168

Example of Frame Relay SVC Operation . . . . 168

Frame Relay Signaling Message Information Elements . . . . 169

Review . . . . 174

▼ ⁸ Connectionless Protocols—IP and SMDS . . . . 175

The Internet Protocol SUITE, TCP/IP . . . . 176

Origins of TCP/IP . . . . 176

TCP/IP Protocol Structure . . . . 177

TCP/IP Networking Context . . . . 178

Generic Link Layer Protocols for IP . . . . 180

IP Version 4 (IPv4) Packet Format . . . . 182

Internet Protocol (IP) Addressing . . . . 183

Next Generation IP—IPv6 . . . . 184

Quality of Service in IP Networks . . . . 186

Transmission Control Protocol (TCP) . . . . 190

User Datagram Protocol (UDP) . . . . 196

Real-Time Transport Protocol (RTP) . . . . 196

Service Aspects of TCP/IP . . . . 198

Switched Multimegabit Data Service (SMDS) . . . . 198

Origins of SMDS . . . . 198

SMDS/IEEE 802.6 Protocol Structure . . . . 199

SMDS/802.6 Protocol Data Unit (PDU) Formats . . . . 199

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Service Aspects of SMDS . . . . 205

Review . . . . 206

▼ ⁹ LANS, Bridging, and Routing . . . . 207

Bridging, Routing, and Internetworking . . . . 208

Basic Terminology . . . . 208

Address Assignment and Resolution . . . . 210

Routing, Restoration, and Reconfiguration . . . . 211

IEEE Local Area Networking (LAN) Standards . . . . 212

Layered LAN Protocol Model . . . . 213

Typical LLC and MAC Sublayer Implementations . . . . 213

The Logical Link Control (LLC) Sublayer . . . . 214

The Media Access Control (MAC) Sublayer . . . . 215

Ethernet and the CSMA/CD 802.3 MAC Sublayer . . . . 217

Ethernet User Priority and VLANs . . . . 219

Token Ring . . . . 220

100 Mbps Fast Ethernet . . . . 222

100VG-AnyLAN . . . . 223

Gigabit and 10 Gbps Ethernet . . . . 224

Fiber Distributed Data Interface (FDDI) . . . . 224

Basic Fiber Distributed Data Interface (FDDI) . . . . 225

Hybrid Ring Control (FDDI-II) . . . . 228

Bridging Concepts, Systems, and Protocols . . . . 229

Bridging Context . . . . 230

A Taxonomy of Bridges . . . . 231

Spanning Tree Protocol . . . . 232

Source Routing Protocol . . . . 233

Bridge Network Design . . . . 234

Routing Concepts, Systems, and Protocols . . . . 235

Packet-Forwarding and Routing Protocol Functions . . . . 235

Link-State Routing Protocols Defined . . . . 238

Routing and Logical IP Subnetworks (LISs) . . . . 242

Address Resolution Protocol (ARP) . . . . 245

Bridging and Routing Systems Design . . . . 247

Review . . . . 249

Part III Foundations of ATM and MPLS: Protocol and Structure ▼ ¹⁰ Introduction to ATM and MPLS . . . . 253

Introduction to ATM and B-ISDN . . . . 254

B-ISDN Protocol Reference Model . . . . 254

B-ISDN Architecture . . . . 255

Overview of the Application of ATM . . . . 256

ATM as a Technology . . . . 257

ATM as a Protocol . . . . 257

ATM as an Interface . . . . 258

ATM as Integrated Access . . . . 259

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ATM as an End-to-End Service . . . . 261

ATM as a Scalable Infrastructure . . . . 261

Origins of MPLS: Reinventing IP over ATM . . . . 263

Ipsilon’s IP Switching . . . . 265

Toshiba’s Cell Switching Router (CSR) . . . . 267

Cisco’s Tag Switching . . . . 267

IBM’s Aggregate Route-Based IP Switching (ARIS) . . . . 270

Early IETF Multiprotocol Label Switching (MPLS) . . . . 272

Introduction to MPLS . . . . 274

Traffic Engineering of IP Networks . . . . 275

Network-Based IP VPN using MPLS Tunneling . . . . 276

Multi-Service MPLS Tunneling . . . . 276

Considerations in the Choice of Cells Versus Frames . . . . 277

Effect of Link Speed on Packet Performance . . . . 277

Rationale for the Choice of ATM Cell Size . . . . 278

Hardware Price-Performance Trade-offs . . . . 279

Review . . . . 280

▼ 11 ATM and MPLS: Physical Layer and Label Switching Functions . . . . 281

Overview of Physical, ATM, and AAL Layer Functions . . . . 282

B-ISDN Protocol Layer Structure . . . . 283

Hardware and Software Implementations of B-ISDN Layers . . . . 284

ATM Physical Layer . . . . 285

Physical Medium–Dependent Sublayer . . . . 285

Transmission Convergence (TC) Sublayer . . . . 287

TC Header Error Check (HEC) Functions . . . . 288

TC Cell Rate Decoupling . . . . 290

Inverse Multiplexing over ATM . . . . 290

xDSL Physical Layer for ATM . . . . 292

ATM Layer . . . . 296

ATM UNI and NNI Defined . . . . 296

ATM Virtual Paths and Channels (VPs and VCs) . . . . 297

The ATM Cell . . . . 302

ATM-Layer QoS and Service Categories . . . . 306

Multiprotocol Label Switching (MPLS) . . . . 308

IP over MPLS Architecture and Terminology . . . . 308

MPLS Forwarding Operations . . . . 309

Example of MPLS Forwarding of IP Packets . . . . 312

MPLS Encapsulation Standards . . . . 312

MPLS Shim Header . . . . 312

MPLS over ATM . . . . 315

MPLS over Frame Relay . . . . 317

Review . . . . 318

▼ ¹² ATM Adaptation and MPLS Tunneling Protocols . . . . 319

ATM Adaptation Layer (AAL) . . . . 320

ATM Adaptation Layer (AAL)—Protocol Model . . . . 320

AAL Protocol Structure Defined . . . . 321

Key AAL Attributes . . . . 322

ATM Adaptation Layer 1 (AAL1) . . . . 323

AAL1 Segmentation and Reassembly (SAR) Sublayer . . . . 324

AAL1 Convergence Sublayer Functions . . . . 325

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AAL2 Protocol Structure and PDU Formats . . . . 333

Example of AAL2 Operation . . . . 335

ATM Adaptation Layer 3/4 (AAL3/4) . . . . 337

AAL3/4 SAR Sublayer . . . . 337

AAL3/4 CPCS Sublayer . . . . 338

Example of AAL3/4 Operation . . . . 339

AAL3/4 Multiplexing Example . . . . 340

AAL5 Segmentation and Reassembly (SAR) Sublayer . . . . 342

AAL5 Common Part Convergence (CPCS) Sublayer . . . . 342

Example of AAL5 Operation . . . . 343

AAL5 Multiplexing Example . . . . 344

Multi-Service Tunneling over MPLS (and Other Protocols) . . . . 346

General Concept of Protocol Tunneling . . . . 346

ATM Forum’s ATM over MPLS Network Interworking . . . . 348

IETF Pseudo Wire Emulation Edge to Edge (PWE3) . . . . 350

“Martini” Multi-Service Encapsulation . . . . 351

Review . . . . 352

▼ ¹³ Higher-Level User and Control Plane Protocols . . . . 353

Overview of Higher-Layer ATM and MPLS Protocols . . . . 354

Circuit Emulation Voice, Video, and WAN Data Protocols . . . . . 354

Local Area Networking and IP-Based Applications . . . . 356

ATM Service Category and AAL Support for Applications . . . . . 358

Overview of ATM and MPLS Control Plane Protocols . . . . 358

Generic Control Plane Functions . . . . 359

Switched and Permanent ATM Virtual Connections . . . . 359

ATM Control Plane Protocols . . . . 360

MPLS Control Plane Protocols . . . . 361

ATM Control Plane Structure and AAL . . . . 361

ITU-T B-ISDN Signaling Protocols . . . . 362

Types of Signaling Channel Association . . . . 363

Layered Signaling AAL Model . . . . 365

Service Specific Coordination Function (SSCF) . . . . 365

Service Specific Connection-Oriented Protocol (SSCOP) . . . . 366

ATM User-Network Interface (UNI) Signaling . . . . 368

Base Signaling Functions: Q.2931 and UNI 3.1 . . . . 368

ATM Forum UNI Signaling 4.0 and ITU-T Standards . . . . 368

ATM Forum UNI Signaling 4.1 and ITU-T Standards . . . . 370

UNI 4.1 Signaling Message Types . . . . 371

Signaling Message Information Elements . . . . 372

Examples of ATM Signaling Procedures . . . . 373

ATM Control Plane Addressing . . . . 378

Control Plane Addressing Levels . . . . 378

ATM Level Addressing . . . . 379

ATM Addressing Formats . . . . 379

ATM Forum ATM End System Address (AESA) Formats . . . . 381

Group Addresses and Anycast . . . . 382

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ILMI Address Registration . . . . 383

Bi-Level Addressing . . . . 384

ATM Name Service (ANS) . . . . 384

Review . . . . 385

▼ 14 MPLS Signaling and Routing Protocols . . . . 387

MPLS Control Plane Architecture . . . . 388

MPLS Control and Forwarding Plane Model . . . . 388

Motivation for Constraint-Based Routing . . . . 389

MPLS Label Distribution Control Protocol Attributes . . . . 391

MPLS Label Distribution Signaling Protocols . . . . 397

Label Distribution Protocol (LDP) . . . . 397

RSVP Traffic Engineering (RSVP-TE) . . . . 400

Constraint-Based Routing LDP (CR-LDP) Extensions . . . . 404

Use of BGP for Label Distribution . . . . 405

IGP Traffic Engineering Extensions: OSPF and IS-IS . . . . 407

General Modifications for Traffic Engineering . . . . 407

Specific Modifications for IS-IS TE . . . . 408

Specific Modifications for OSPF-TE . . . . 408

Open Issues and Challenges Ahead . . . . 409

Example Applications of MPLS in IP Networks . . . . 409

Traffic Engineering in an IP Backbone . . . . 409

Label Distribution in Support of Other Services . . . . 411

MPLS Connectivity Across Multiple Providers . . . . 412

Review . . . . 413

▼ ¹⁵ ATM NNI Signalinag and Routing Protocols . . . . 415

Interim Interswitch Signaling Protocol (IISP) . . . . 416

Private Network-Network Interface (PNNI) . . . . 416

Architecture and Requirements . . . . 417

Network Addressing Philosophy . . . . 418

A Tale of Two Protocols . . . . 419

PNNI Routing Hierarchy and Topology Aggregation . . . . 420

Beyond Connectivity to Quality and Bandwidth . . . . 427

Soft Permanent Virtual Connections (SPVCs) . . . . 431

Minimum Interoperable PNNI 1.1 Subset . . . . 432

Broadband InterCarrier Interface (B-ICI) . . . . 433

B-ISDN User Services Part (BISUP) . . . . 433

B-ICI’s Replacement: ATM Inter-Network Interface (AINI) . . . . 434

Extended PNNI and AINI Routing and Signaling Capabilities . . . 436

Review . . . . 439

Part IV ATM and MPLS Support for Networking Applications ▼ ¹⁶ Enabling Voice, TDM, and Video Over ATM and MPLS . . . . 443

Packet Voice Networking . . . . 444

General Network Architecture . . . . 445

Media Gateway Functions . . . . 446

Packet Voice Encoding Standards . . . . 446

Quality Considerations . . . . 448

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Broadband Local Loop Emulation Using AAL2 . . . . 459

Circuit Emulation Using ATM and MPLS . . . . 463

AAL1-Based Circuit Emulation Service (CES) . . . . 463

Circuit Emulation over MPLS . . . . 466

Video over ATM and Packet Networks . . . . 467

Commonly Used Video Coding Standards . . . . 467

MPEG-2 Video Over ATM and Packet Networks . . . . 468

QoS Considerations Related to Video . . . . 471

Review . . . . 472

▼ ¹⁷ Connection-Oriented Protocol Support . . . . 473

Interworking, Access, and Trunking . . . . 474

Overview of Frame Relay/ATM Interworking . . . . 477

Frame Relay/ATM Network Interworking . . . . 478

FR Service-Specific Convergence Sublayer (FR-SSCS) . . . . 479

Status Signaling Conversion . . . . 480

Congestion Control and Traffic Parameter Mapping . . . . 480

Frame Relay/ATM Service Interworking . . . . 481

Status Signaling Interworking . . . . 482

Address Resolution Protocol Interworking . . . . 483

FR/ATM SVC Service Interworking . . . . 484

FR/ATM Interworking Applied . . . . 486

ATM Access to SMDS . . . . 488

Frame-Based Interfaces Supporting ATM . . . . 489

ATM Data Exchange Interface (DXI) . . . . 489

Frame-Based User-Network Interface (FUNI) . . . . 493

Frame-Based ATM over SONET/SDH Transport (FAST) . . . . 496

Frame-Based ATM Transport over Ethernet (FATE) . . . . 497

MPLS-Based Support for Link Layer Protocols . . . . 498

Pseudo-Wire and Service Emulation Considerations . . . . 499

Martini Encapsulation and Transport of FR, AAL5, ATM, and HDLC . . . . 500

FR over MPLS Network Interworking . . . . 502

Review . . . . 503

▼ 18 ATM and MPLS Support for LAN Protocols . . . . 505

Multiprotocol Encapsulation over AAL5 . . . . 506

Protocol Encapsulation . . . . 506

VC-Based Multiplexing . . . . 508

Considerations in the Selection of Multiplexing Method . . . . 510

ATM Forum LAN Emulation (LANE) . . . . 511

Hardware and Software in an Emulated LAN . . . . 511

LANE Components and Connection Types . . . . 514

Summary of LANE Operation . . . . 514

LANE and Spanning Tree . . . . 518

LANE Implementation Considerations . . . . 519

Ethernet over MPLS . . . . 520

Martini Encapsulation of Ethernet over MPLS . . . . 520

Virtual Private LAN Service (VPLS) . . . . 521

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VPLS and Access to the Internet . . . . 525

Interworking Network Layer Protocols over MPLS . . . . 526

Metropolitan and Wide Area Ethernet over MPLS Networking . . . . 528

Review . . . . 530

▼ ¹⁹ ATM and MPLS Support of Enterprise-Level IP Networks . . . . 531

IP over ATM Virtual Private Networks . . . . 533

Classical IP over ATM . . . . 533

Multiprotocol over ATM (MPOA) . . . . 537

IP Multicast over ATM . . . . 542

IP Virtual Private Networks (VPN) over MPLS or IP Tunnels . . . . 545

General Virtual Private Network (VPN) Terminology and Concepts . . . . 545

Network-Based IP VPN Concepts . . . . 548

Aggregated Routing Network-Based VPNs Using Tunnels . . . . 550

Virtual Router Network-Based VPNs using Tunnels . . . . 554

Considerations and Trade-offs with Network-Based IP VPNs . . . . 556

Considerations Regarding Choice of Tunnel Type . . . . 557

VPN Representations and Configuration Complexity . . . . 558

IP Path Maximum Transfer Unit (MTU) Discovery . . . . 560

MTU Path Discovery over AAL5 . . . . 560

MTU Path Discovery over MPLS . . . . 561

Review . . . . 562

Part V Quality of Service, Traffic Management, and Congestion Control ▼ ²⁰ The Traffic Contract and Quality of Service (QoS) . . . . 565

The Traffic Contract . . . . 566

Reference Models . . . . 567

Generic Allocation of Impairments Model . . . . 567

ATM Equivalent Terminal Model . . . . 568

Diffserv Per-Hop and Per-Domain Behavior Models . . . . 569

Quality Of Service . . . . 571

Application QoS Requirements . . . . 571

ATM QoS Parameters . . . . 573

IP Performance Metrics (IPPM) . . . . 578

Traffic Parameters and Conformance Definitions . . . . 579

ATM Traffic Descriptor . . . . 579

IP Traffic Descriptor . . . . 582

ATM Conformance Definitions . . . . 583

IP Traffic Conformance Definitions . . . . 585

Classes of Service . . . . 586

ATM Forum QoS Classes and Service Categories . . . . 586

ITU-T ATM QoS Classes . . . . 588

Mapping Between ATM Forum and ITU-T QoS Definitions . . . . 591

Diffserv Per-Hop Behaviors (PHBs) . . . . 594

MPLS Support for Diffserv . . . . 595

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Switch Modifications to Support GFR . . . . 601

UBR with BSC and MDCR . . . . 603

Use of Differentiated UBR to Support Diffserv . . . . 604

Use of Differentiated UBR to Support IEEE 802.x . . . . 605

UBR Service Category with Optional MDCR Parameter . . . . 605

Review . . . . 607

▼ 21 Traffic Control, QoS Mechanisms, and Resource Management . . . . 609

Achieving Conformance . . . . 610

Checking Conformance: Policing . . . . 612

ATM Policing . . . . 613

Examples of Leaky Bucket Policing . . . . 613

Generic Cell Rate Algorithm (GCRA) and Virtual Scheduling . . . . 619

IP and MPLS Policing . . . . 620

Ensuring Conformance: Shaping . . . . 624

Overview of Possible Shaping Methods . . . . 625

Leaky Bucket Buffering . . . . 626

Token Bucket Shaping . . . . 627

Delivering QoS: Prioritization, Queuing, and Scheduling . . . . 630

Prioritized Queuing and Scheduling . . . . 630

Priority Discard Thresholds . . . . 631

Performance Implications of Priority Control . . . . 632

Overview of Weighted Scheduling Algorithms . . . . 633

Meeting the Traffic Contract: Resource Management . . . . 634

Admission Control . . . . 634

ATM VPs and Label Stacked MPLS LSPs . . . . 638

Review . . . . 640

▼ 22 Congestion Control . . . . 641

Congestion: A Familiar Phenomenon . . . . 642

The Nature of Congestion . . . . 642

Busy Seasons, Days, and Hours . . . . 643

Impact of Congestion . . . . 644

Examples of Congestion in a Network . . . . 644

Congestion Control: A Range of Solutions . . . . 645

Open- and Closed-Loop Congestion Control . . . . 645

Impact of Congestion on Performance . . . . 646

Categorization of Congestion Control Approaches . . . . 649

Congestion Management . . . . 652

Resource Allocation . . . . 652

Network Engineering . . . . 652

Congestion Avoidance . . . . 653

Congestion Indication . . . . 653

Policing and Tagging . . . . 654

Connection Blocking . . . . 654

Closed-Loop Flow Control . . . . 654

Generic Closed-Loop Flow Control Methods . . . . 655

ATM Generic Flow Control (GFC) . . . . 656

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Available Bit Rate . . . . 657

The Great Rate Versus Credit Debate . . . . 659

Congestion Recovery . . . . 667

Selective Discard . . . . 667

Early/Partial Packet Discard (EPD/PPD) . . . . 668

Dynamic Usage Parameter Control (UPC) . . . . 670

Disconnection and/or Rerouting . . . . 670

Operational Procedures . . . . 671

Review . . . . 671

Part VI Communications Engineering, Traffic Engineering, and Design Considerations ▼ 23 Basic Communications Engineering . . . . 675

Philosophy . . . . 676

Communications Channel Model . . . . 676

Deterministic Versus Random Modeling . . . . 677

Probability Theory . . . . 677

Randomness in Communications Networks . . . . 677

Random Trials and Bernoulli Processes . . . . 678

The Normal/Gaussian Distribution . . . . 678

Common Digital Signals and Their Spectra . . . . 679

The Telegraph Pulse: Binary On/Off Keying . . . . 680

A Better Way: Pulse Shaping . . . . 681

Pushing the Envelope: Quadrature Amplitude Modulation . . . . . 681

Error Models and Channel Capacity . . . . 685

Typical Communications Channel Error Models . . . . 685

Shannon’s Channel Capacity . . . . 686

Error Performance of Common Modulation Methods . . . . 688

Error-Detecting and -Correcting Codes . . . . 689

Simple Parity Check Schemes . . . . 689

Cyclical Redundancy Check (CRC) Codes . . . . 690

Performance of ATM’s HEC . . . . 691

Undetected Error Performance of HDLC and AAL5 . . . . 694

Data Compression . . . . 694

Review . . . . 696

▼ 24 Traffic Engineering . . . . 697

Philosophy . . . . 698

Source Model Traffic Parameter Characteristics . . . . 698

Modeling Accuracy . . . . 699

Overview of Queuing Theory . . . . 699

General Source Model Parameters . . . . 699

Poisson Arrivals and Markov Processes . . . . 702

Queuing System Models . . . . 705

Call Attempt Rates, Blocking, and Queuing . . . . 708

Statistical Model for Call Attempts . . . . 708

Erlang’s Blocked Calls Cleared Formula . . . . 709

Erlang’s Blocked Calls Held Formula . . . . 711

Performance of Buffering Methods . . . . 713

Input Versus Output Queuing Performance . . . . 713

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Equivalent Capacity . . . . 720

Fluid Flow Approximation . . . . 721

Statistical Multiplex Gain Model . . . . 722

Equivalent Capacity Approximation . . . . 726

Priority Queuing Performance . . . . 728

Review . . . . 730

▼ 25 Design Considerations . . . . 731

Impacts of Delay, Loss, and Delay Variation . . . . 732

Impact of Delay . . . . 732

Impact of Loss . . . . 735

Impact of Delay Variation . . . . 738

TCP Performance Considerations . . . . 742

TCP Window Size Impact on Throughput . . . . 742

TCP over ATM: UBR and ABR . . . . 742

TCP/IP Performance in a Congested Scenario . . . . 743

Voice and Data Integration . . . . 745

Voice Traffic Model . . . . 745

Statistically Multiplexing Voice Conversations . . . . 746

Voice/Data Integration Savings . . . . 747

Overview of the Network Planning and Design Process . . . . 748

Network Design Approaches and Modeling Philosophy . . . . 749

Measuring Traffic and Performance Data . . . . 750

Analyzing and Simulating Candidate Networks and Technology . . . . 751

Practice Makes Perfect . . . . 752

Network Design and Modeling Tools . . . . 753

Design Tool Graphical User Interface (GUI) . . . . 753

Specifying Design Scenarios . . . . 754

Modeling Network-Specific Capabilities . . . . 755

Displaying and Comparing Results . . . . 755

Review . . . . 756

Part VII Operations and Network Management for ATM and MPLS ▼ 26 Operational Philosophy and Network Management Architectures . . . . 759

OAM&P Philosophy . . . . 760

Administration . . . . 760

Provisioning . . . . 761

Operations . . . . 762

Maintenance . . . . 762

Unique Challenges Created by ATM . . . . 763

Unique Challenges Created by MPLS . . . . 763

Network Management Architectures . . . . 764

Centralized Versus Distributed Network Management . . . . 764

OSI Network Management Functional Model . . . . 765

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ITU Telecommunications Management Network (TMN) . . . . 766

ITU-T Generic Transport Network Architecture . . . . 769

ATM Forum Network Management Architecture . . . . 772

Review . . . . 773

▼ 27 Network Management Protocols and Management Information Bases (MIBs) . . 775 Network Management Protocols . . . . 776

IETF Simple Network Management Protocol (SNMP) . . . . 776

ITU-T Common Management Interface Protocol (CMIP) . . . . 780

Proprietary Network Management Protocols . . . . 781

Considerations on Choice of Network Management Protocol . . . . 782

ATM Management Information Bases (MIBs) . . . . 782

ATM Forum Integrated Local Management Interface (ILMI) . . . . 783

IETF AToM MIBs . . . . 786

Other ATM MIBs . . . . 787

MPLS Management Information Bases (MIBs) . . . . 787

Label Switch Router (LSR) and Related MIBs . . . . 788

Traffic Engineering (TE) MIBs . . . . 789

Multiservice PPVPN and PWE3 MIBs . . . . 789

IP-Based Management Tools for MPLS . . . . 790

ICMP PING and Traceroute . . . . 790

Vendor-Proprietary ICMP Extensions for MPLS . . . . 791

IETF Direction for IP-Based MPLS Management . . . . 792

Review . . . . 793

▼ 28 ATM and MPLS Management and Performance Measurement . . . . 795

ATM OAM Flow Reference Architecture . . . . 796

ATM OAM Cell Formats . . . . 798

ATM OAM Fault Management . . . . 800

AIS and RDI Theory and Operation . . . . 800

Loopback Operation and Diagnostic Usage . . . . 802

Continuity Check (CC) . . . . 806

ATM Protection Switching . . . . 806

ATM Performance Specification and Measurement . . . . 810

Network Performance and Quality of Service . . . . 810

ATM Performance Measurement (PM) . . . . 810

NP/QoS Parameter Estimation . . . . 814

MPLS OAM Status and Direction . . . . 819

Overview of ITU Direction for MPLS OAM . . . . 819

MPLS Protection Switching and Fast Rerouting . . . . 820

Review . . . . 820

Part VIII Design Considerations and Future Directions Involving ATM and MPLS ▼ 29 Design Considerations for ATM and MPLS Networks . . . . 825

Efficiency Analysis . . . . 826

Circuit Emulation Efficiency . . . . 826

Packetized Voice Efficiency . . . . 828

Efficiency of Cells Versus Frames for Packet Switching . . . . 829

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Scalability Analysis . . . . 837

Addressing and Hierarchy . . . . 837

Supported User and Routing Table Growth . . . . 838

Packet Forwarding and Moore’s Law . . . . 839

Connection-Oriented Versus Connectionless Paradigms . . . . 840

Support for a Wide Range of Interfaces and Speeds . . . . 841

Capacity Bottlenecks . . . . 842

Complexity Analysis . . . . 842

To Switch or Not to Switch? An Answer to This Question . . . . 842

Keep It Simple to Succeed . . . . 843

Hardware Is Hard, but Software Is Harder . . . . 843

Are QoS and Bandwidth Reservation Really Necessary? . . . . 844

Reliability, Availability, and Stability . . . . 846

Supportability and Operability . . . . 847

Security . . . . 847

Review . . . . 848

▼ 30 Future Directions and Applications Involving MPLS and ATM . . . . 851

Future Directions and Applications of ATM . . . . 852

Multiservice Backbone Network Infrastructure . . . . 852

Convergence and Integrated Access . . . . 853

Lessons Learned from ATM for Multiservice Networking . . . . 853

Don’t Operate at the Per-Flow Level . . . . 853

Use Basic QoS and Traffic Management on Aggregates . . . . 854

Use Bandwidth Reservation for Constraint-Based Routing . . . . . 854

Assume a Heterogeneous Underlying Network . . . . 854

Future Applications and Directions of MPLS (and IP) . . . . 855

Next Generation Multiservice Network Infrastructure . . . . 855

Optical Networking for Scalability . . . . 855

Generalized MPLS (GMPLS) . . . . 857

Separation of Forwarding and Control . . . . 860

Possible Future of Multiservice Networking . . . . 861

What Will Continue the Internet’s Explosive Growth? . . . . 861

Will MPLS Become the Ubiquitous Multiservice Network? . . . . . 862

Will GMPLS Effectively Control Next-Generation Backbones?. . . . 863

What Will Happen to ATM? . . . . 863

Review . . . . 863

▼ ^A Acronyms and Abbreviations . . . . 865

▼ ^B References . . . . 881

▼ ^Index . . . . 913

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ABOUT THE AUTHORS

Dr. David E. McDysanis a fellow at WorldCom in the Internet architecture & technology department. He specializes in network cost optimization, next generation edge and core router technology, IP QoS, network-based VPNs, Voice over IP, and Internet standards. Prior to this assignment, he led an architectural planning group for next-generation switched networks at MCI and MCI WorldCom. During the mid-1990s, he designed and managed the commercial ATM network for MCI. David is currently active in the Internet Engineering Task Force (IETF). He has held leadershiproles in the Multiservice Switching Forum and the ATM Forum. He has authored books on VPNs, QoS and traffic management, and coauthored three books on ATM.

Dave Pawis currently a consultant for telecommunications network design. Prior to this, he was a senior engineer, developing architectural options for next-generation networks. His expertise encompasses multi-service ATM and Frame Relay solutions, metro access networks, and optical control networks. Dave provided PNNI and MPLS expertise in the Network Architecture and Advanced Technology organization at WorldCom, and was active in the ATM Forum. Before his involvement with data network architectures, he produced detailed specifications for the WorldCom SONET/SDH and Digital Cross Connects, and was part of the group that planned and developed WorldCom's first DWDM infrastructure. When he’s not working on network designs, Dave involves him- self with inter-cultural and inter-religious projects.

ABOUT THE TECHNICAL EDITORS

Richard Carrarais currently a senior network architect at Data Return, Inc., based in Irving, Texas. He is a CCIE and CISSP with more than eight years of information technology experience. He specializes in the design and architecture of secure, large-scale IP networks.

Lei Yaois a Ph.D. candidate in the department of Electrical and Computer Engineering at George Washington University. His research interests include IP-QoS, queuing theory, traffic control, and IP routing. He has published more than 10 papers on related topics. He got his M.S. in Computer Engineering from the Institute of Automation, Chinese Academy of Sciences, in 1996. From 1999 to 2002, he was a senior network engineer at WorldCom, where he was a lead engineer on various IP-QoS, MPLS and IP-VPN projects, and coauthored four Internet drafts and seven U.S. patent applications.

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THE PURPOSE OF THIS BOOK

W

hy did we decide to update this book on ATM once again? Mainly, because the publisher asked us to! Seriously, though, in the fast moving telecommunications industry, a lot has happened since the publication of the last edition in 1998. In case you have been asleep, Internet-based communication is clearlythekiller application for networking. Much effort is being expended for it to support an ever-broader range of communications applications in a more cost-effective manner. During the early part of the Internet growth spurt in the mid-1990s, ATM was an essential technology employed by Internet service providers to provide higher-speed switching than the routers of that time could support. However, since ATM was not designed specifically to support IP, and was actually somewhat inefficient in doing so, there arose a strong motivation to take the best parts of ATM and put them into a protocol specifically designed to provide a high performance, cost effective infrastructure for IP. The result of that effort has become known as Multiprotocol Label Switching (MPLS). This is the reason that this acronym now shares the title of this edition with ATM.

Therefore, we chose to add to this edition an extensive amount of new material on MPLS, which was in a formative stage back in 1998. Because of its heritage of providing better support for IP networks, MPLS shares some important characteristics with ATM, but also has some important differences. Similarities include support of traffic engineering, Quality of Service, and the use of signaling protocols to

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establish efficient switching using locally significant labels. However, ATM was envisioned at the outset with a multi-service mindset that would support any previously-con- ceived communication service, and hence has support for things like voice, circuit emulation, and support of Frame Relay designed into it from the ground up. On the other hand, MPLS was designed specifically to support IP, and hence has a unique set of functions here that ATM does not; for example, a time-to-live counter that helps avoid routing loops. Interestingly, the designers of MPLS have recently focused on a goal similar to the multi-service vision of ATM. These functions are now being added to the MPLS infrastructure, but also consider support of multiple services over IP and not just MPLS.

This book covers aspects of ATM and MPLS in parallel so that the reader can see these similarities and differences, and appreciate the impact they have on the practical application of these approaches in a network context. We now give a brief summary of how the contents of this book have changed from the previous edition, with Chapter 1 providing a more in depth overview of the book.

Part 1 of this edition removes much of the ATM marketing hype of the previous edition. Instead, it provides a more detailed outline of the book, along with more up-to-date motivation and a summary of the standards organizations that produce much of the technical content described in this book.

Part 2 of this edition retains the extensive background information on general communications technology and the historical development of voice and data protocols can be used as a introductory course to communications or as a practical reference guide for the practicing professional. It adds significant updates in the areas of Frame Relay, Ether- net, and IP, and removes some details for other protocols like X.25, FDDI, and SMDS that are in the sunset of application. Most commercial Frame Relay networks run over ATM, and therefore this is an area of focus of this edition. We chose to continue to dedicate many pages to these descriptions of services that were an integral part of the multi-service vision of ATM, which is now being adopted by MPLS and IP.

Part 3 covers the basics of ATM and MPLS, starting at the physical layer and moving up through the protocol stack to functions necessary to support a multi-service networking environment. This includes not only those functions necessary to forward ATM cells or MPLS packets, but also those necessary to determine the route and signal the association of labels to the path that these cells or packets follow. Support for higher-layer applications over ATM has seen somewhat limited application, and the coverage of these areas in Part 4 is reduced to make room for new material on how MPLS and IP networks could potentially achieve the multi-service vision originally envisioned by the designers of ATM.

Also expanded on in this edition in Part 5 are updates on the hallmark of ATM—traffic management and Quality of Service (QoS). This edition adds material on the initial application of these concepts in IP and MPLS networks. Part 6 contains an introduction to basic communications engineering as well as some updates to traffic engineering extended to apply to MPLS and IP as well as ATM networks. As is often the case in many communication technologies, network management is often the last subject addressed, and MPLS networks are no exception. Because ATM is relatively mature, the standards and approaches for managing ATM-based networks have also matured and Part 7 updates

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When the ancient Chinese said, “May you live in interesting times,” they meant it as a curse. Their bureaucratic society abhorred change, preferring the comfort of stability over the uncertainty of progress. Part 8 explores the current era of interesting times in communication and computer networking. This final part contains mostly new material.

Starting in the wide area network where efficient use of expensive WAN bandwidth is key, the text objectively studies the efficiency of voice, video, and data over ATM and MPLS or IP packet networks. We also consider the more difficult-to-quantify subjects of complexity, scalability, and reliability, moving into the local area network, where equipment price and simplicity are key considerations, because bandwidth is much less expensive in the local area when compared with the wide area. An interesting divide is the Metropolitan area network, where new applications of ATM and MPLS are being designed and deployed.

INTENDED AUDIENCE

This book can be used as an up-to-date comprehensive textbook on communications networking, since it covers much more than just ATM and MPLS. We have taken this ap- proach, since both ATM and MPLS have adopted the charter of supporting multiple services. In order to understand how this is done, a complete treatment must describe each of the multiple services that are supported. It focuses on protocols, operation, standards, technology, and services for use by the communications manager, network design engineer, practicing professional, or student of data networking. This book also captures important historical aspects of the development of these technologies. In general, we provide a summary augmented by an extensive list of technical references for the reader who wishes to further delve into a particular subject.

The reader should have some prior knowledge of telecommunications principles, al- though most of the basic concepts of communication networking are covered in Part 2.

Not only will the technical professional benefit from this book, but sales and marketing, end users of the technology, and executives will gain a more in-depth view of how ATM and MPLS technology and services can impact their businesses. This book should also help practicing engineers become well-versed in the principles and empower them to communicate these principles effectively to their management. While we strove to keep the text accurate upto the time of publication, the reader is urged to use the references provided to confirm information and obtain the latest published standards.

HOW TO USE THIS BOOK FOR COURSES

This book can be used to teach a single-semester course focused on MPLS and/or ATM, or as a two-semester course on data communications with a focus in the second semester on

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the details of MPLS and/or ATM. It can be used as an intermediate-level text for data communications, or can be used as a companion volume when used with an introductory book.

If the subject matter is to be taught over two semesters, we recommend that the text be broken into two parts. Material for use in a first-semester course on a introduction to data communications and basic architectures, protocols, technologies, and services could include Parts 1, 2, 3, and 4. Chapters of focus for a second-semester course on advanced MPLS and ATM protocols and technologies could cover Parts 5, 6, 7 and a recap of Part 4, with either selected outside reading or a research assignment.

A single-semester course dedicated to data communications services (circuit switching, Frame Relay, Ethernet, IP, ATM and MPLS) focusing on MPLS and/or ATM should consider selections from Parts 1, 2, 3, 4 and 5. The student should have a minimum working knowledge of the material contained in Part 2 if this book is used in a single-semester course.

Labs should contain design problems based on the cumulative knowledge gained from the class readings and outside reading assignments (e.g., recent technology updates or application notes from vendor Web sites). Assigned exercises should involve multiple end-system and intermediate-system design problems. Because of the fluid nature of emerging standards, students should be encouraged to use the text as a working docu- ment, noting any changes as the standards from the sources listed in the appendices are revised and updated. This is your book—write in it!

AUTHORS’ DISCLAIMER

Accurate and timely information as of the date of publication was provided. Some of the standards we’ve used were merely drafts at the time of writing, and we assumed that they would become approved standards by the time of publication. At times, we present material that is practical for a large-scale design, but must be scaled down for a smaller enterprise environment. Many data communications networks will operate and continue to run quite well on a dedicated private line network, but eventually the economics of switched technologies and services, even on the smallest scale, are worth investigating.

Please excuse the assumption that the user is ready for these advanced technologies—in some cases it may take some time before these technologies can be implemented.

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Overview, Introduction, Background, Motivation, and Standards

T

he first chapter provides a brief introduction to ATM and MPLS, summarizing the various aspects of the technology, including protocols, multi-service support, and network design and operation.

We then provide an overview in the form of a summary outline of the remainder of the book so that the reader can use this as a guide from which to continue reading, as well as make use of it as a reference for finding material on a particular subject. Chapter 2 then provides additional background and motivation for ATM and MPLS networking, and the

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multiple services for which they provide infrastructure. Finally, Chapter 3 summarizes the standards bodies active in the specification of ATM and MPLS protocols, along with other protocols that state how they support other services and applications. Knowing how to get standards and what the respective roles are of the various organizations is essential background for further study.

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Introduction to ATM and MPLS and Overview of the Book

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W

hat the heck are ATM and MPLS, and why should I care? In short, the answer is that ATM and MPLS are usually infrastructure and not a service for end users or applications. This means that a residential user will probably never have di- rect access to these protocols as an end-to-end service. Furthermore, only larger enter- prises will make use of them as either purchased from a service provider or as infrastructure within a privately owned and managed network. Electronic equipment (e.g., a switch or a router) implements ATM and MPLS functions on interfaces that connect to transmission systems. A network is a set of ATM or MPLS nodes containing such equipment connected by transmission links, like that shown in Figure 1-1. These nodes exchange digitally encoded messages over these lines, either for the purpose of forwarding packets of information to a specific destination, or for internal control and management purposes. These nodes may also have external interfaces that provide other services to end users or customers. As shown in the upper left-hand corner of the figure, each ATM cell or MPLS packet of information has a header that has an identifier, or label, that determines what packet forwarding action the next node should take. In the example of the figure, originating node 1 prepends the label A to some information and sends it to node 2. This node has an entry in its forwarding table that indicates that packets received with label A are to be sent to node 4, and that the label should be changed to B before doing so. In ATM and MPLS, control protocols form an association of a sequence of label forwarding actions along a sequence of nodes between a source and a destination, form- ing what is called an ATM Virtual Connection (VC) or an MPLS label switched path (LSP), as shown at the top of the figure.

Okay, if we just told you what ATM and MPLS are in a paragraph and one drawing, then why is there an entire huge book on the subject? The answer is that actually imple- menting the relatively simple networking concept just described turns out to have a rather intricate and complex solution. Why is the solution so complicated, you ask. The answer has several dimensions, all related to the addition of complexity in order to

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Figure 1-1. Generalized communication network concept and terminology

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challenging electro-optical design problem. In order to keep costs in line, engineers must define incredibly detailed standards for interfaces between nodes (and even interfaces between chips within the same node) to allow manufacturers to specialize in developing certain components and systems and achieve certain economies of scale.

But this isn’t even the really hard part. Unless one is careful in designing a data communications network, the costs of paying for people to operate the network and/or developing software just to maintain it can be greater than the cost of the ATM or MPLS nodes and the transmission links that connect them. Designers have addressed this problem by developing control protocols that automate many of the tasks involved in operat- ing a network. For ATM, many of these protocols are derived from the telephone network, while for MPLS, many of the protocols are based upon those originally developed to run the Internet. For example, questions of how to automate discovering what the other nodes and links are in a large network, determining the best path for labeled packets to traverse, and signaling the configuration of this path are all complicated algo- rithmic problems. Add to this the fact that these algorithms are implemented as computer communication protocols in software, which must have voluminous specifications such that nodes manufactured by different companies and/or networks operated by different organizations can understand each other. And as history has taught us, a large computer program is an incredibly complex thing to develop, maintain, and operate. Progress is continually made in the area of protocol development, since a large number of vendors and service providers have a compelling interest to make it all work automatically, because automation achieves a tremendous cost savings as compared with manual configuration. And in fact, automation is essential for networks beyond even a modest size in order to implement packet-switched communication at all.

Unfortunately, the drivers for adding complexity don’t stop there. Since ATM and MPLS are usually an infrastructure, and not a native service meaningful to an end-user device, engineers must precisely agree on how to adapt a native service protocol (e.g., IP) to a specific configuration of ATM or MPLS. Often this adaptation is itself also another form of infrastructure within a service provider or enterprise network. Inside a network, there are often many ATM or MPLS paths that can compete for resources at a node or transmission line. Therefore, a whole science of applied algorithms has been defined to route traffic to achieve a desired performance level, or Quality of Service (QoS). This can be quite important, because some applications need a certain level of QoS in order to function properly. There is also a driver to have complex routing algorithms to minimize cost of expensive interfaces on ATM or MPLS nodes and the transmission links that connect them. And once we’ve defined the solution to all of these problems, there is always a need to do some amount of configuration, and based upon similar motivations there is a strong desire to automate such activities to a certain extent to reduce ongoing operational costs. Finally, within such a complex networking environment, it is inevitable that at some point something will go wrong. Therefore, a whole suite of management approaches and protocols have been defined so that organizations can operate, manage, and diagnose problems in ATM and MPLS networks.

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Therefore, the trick is to define just the right amount of complexity that gets the job done efficiently and reliably. The description of the various aspects of complexity in ATM and MPLS just given is essentially the outline of the book beginning at Part 3. The balanc- ing act between complexity and cost effectiveness is a challenging engineering trade-off and one that changes over time. Change has a number of sources. New science or designs can drive fundamental technological advances. Other changes occur as a result of market forces when the industry adopts a de facto standard set by some vendor or service provider. Also, regulation can play a role in changing the telecommunications geo-economic landscape. Therefore, there is also a natural evolution of packet-switching technology that is driven by these changes as well as the relentless human drive for ongoing innova- tion and improvement. Communications engineers have been working on refining the solution to the same basic problem of labeled packet switching for almost three decades, and just summarizing this history takes several hundred pages in Part 2 of this edition. In fact, many of the services supported in the multi-service vision of ATM and now MPLS are these legacy services. Continuing to support legacy services on next-generation infrastructure was an important tenet of ATM that is now being carried forward by MPLS.

So, we have a lot of material to cover to completely address the complexity defined to achieve a reasonable level of cost effectiveness just described. Since this is a large set of subjects, each with quite a bit of detail, the remainder of this chapter provides an overview of the contents of the rest of this book as a guide for the reader. This is useful to read over to get an understanding of the way we have organized the material to helpyou in deciding in what order to read these chapters. Furthermore, since many chapters cross-reference the material in other chapters, having an understanding of the outline should help you find information more easily.

OVERVIEW OF THIS BOOK

This book not only reviews highlights of standards, but it also applies the concepts through illustrations, examples, and real-world applications to make the transition from theory to application. It strives to teach the reader not only what the ATM- and MPLS-based technologies involve, but also why each subject is important. Since the Internet has become the de facto networking protocol standard, we focus a great deal of material on how ATM and MPLS apply to the Internet, as well as to intranets and extranets.

This text covers the three critical aspects of ATM and MPLS: drivers, technology, and practical, hands-on application. It interleaves descriptive material replete with many drawings with application notes along with the results of actual networking experience.

The book gives examples for network planners, development engineers, network designers, end users, and network managers. The text cites numerous references to complemen- tary texts and sources for the reader interested in more detail.

ATM and MPLS: Theory and Application: Foundations of Multi-Service Networkingis ar- ranged in eight parts, each with several chapters.

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Chapter 1provides a high-level introduction to ATM and MPLS, differentiating their role from other protocols as a foundational network infrastructure and not an end-user service. It also contains an overview, or roadmap, for this rather long book. Refer back here or to the table of contents if you are looking for specific information.

Chapter 2summarizes some of the motivations for ATM and MPLS. It summarizes the changing environment of computing and communication networking and how this af- fects the evolving corporate communications environment. The scope ranges from the desktopto the local area network and client/server networking domains, to the rapidly growing world of the Internet, intranets, and extranets. An important trend is that changing operational and competitive paradigms demand higher performance communications at reduced unit costs. Further benefits, such as integration savings, flexibility, and economies of scale of multi-service networking, are also important. There is also a set of technology trends that shape the development of solutions in response to these needs, including processor enhancements, modernized transmission networks, and decreasing switch and router costs.

Chapter 3describes the ATM and MPLS standards bodies and the manner in which they define the standards and specifications, complete with references to the major standards used in this book and how to acquire them. It summarizes the standards process and how standards affect real-world implementations and networks.

Part 2presents a comprehensive background on communications networking and protocols, and can be used for a course on these subjects. This includes the basic concepts of multiplexing and switching, an introduction to layered protocol models, and tutorials on the major communication networking techniques in use today in the networking envi- ronments.

Chapter 4covers basics of network topologies, circuit types and services, and asynchronous and synchronous transmission methods. The definitions of the terms asynchronous and synchronous are covered in detail. This chapter concludes with a comprehensive review of the principles of multiplexing and switching, with key points illustrated through examples.

Chapter 5begins with a brief history of packet switching. It then introduces the basic protocol layering concepts used throughout the book. The text then discusses several layered protocol architectures as applied examples of layered protocols, for example, open systems interconnection (OSI) and the Internet. It also presents a discussion of connectionless and connection-oriented data services.

Chapter 6then introduces the connection-oriented digital Time Division Multiplexing (TDM) communication technique widely used in contemporary voice and private line networks. The text then moves on to an in-depth review of one of ATM’s key ancestors:

the Narrowband Integrated Services Digital Network (N-ISDN) protocol stack. Here, the reader is introduced to the concept of multiple planes of layered protocols serving the user, control, and management functions.

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Chapter 7covers the key connection-oriented packet-switching protocols in use today:

X.25 and Frame Relay, with a focus on the latter. The text gives the origins of each protocol, their structure, and protocol details. Examples illustrate key points of operation for each protocol. The text separates the description of the user and control plane protocol stacks for Frame Relay as an introduction to a similar separation of function employed in ATM and MPLS.

Chapter 8describes the key connectionless packet switching protocols defined for use in communication networks. The focus is on the Internet Protocol (IP), with some historical information also provided for Switched Multimegabit Data Service (SMDS). This chapter traces the background of each protocol, details the packet formats, and illustrates key operational aspects through examples. The text not only covers IP, but summarizes the entire Internet protocol suite composed of transport and other major application protocols that support e-mail, the Web, and streaming media applications like voice and video.

Chapter 9presents a tutorial on bridging and routing as background for applications described in Part 4 that support these important services. The text first introduces basic terminology and concepts, some of which have been adopted in ATM and MPLS control protocols. It then describes commonly used LAN protocols like Ethernet, Token Ring, and FDDI. The text then introduces the concepts of routing and addressing.

Part 3covers the basics of the ATM and MPLS protocol landscape, providing a struc- tured introduction and reference to all terminology, protocols, and standards.

Chapter 10introduces the overall broadband ISDN (B-ISDN) protocol reference model in terms of the user, control, and management planes. The layers common to all of these planes are physical, ATM, and ATM Adaptation Layer (AAL). It then provides a high-level introduction to ATM. We then summarize the origins of MPLS as a method of improving on the traffic engineering of early IP over ATM networks. It then provides an introduction to MPLS. This chapter concludes with a discussion of consideration of the choice between fixed-length ATM cells and variable-length packets.

Chapter 11details the physical layer and ATM layer and corresponding MPLS protocols. The text describes how a single ATM layer operates over a number of physical media. It also introduces the concepts of the ATM traffic contract, ATM service categories, and Quality of Service (QoS), leaving further details to Part 5. This chapter covers the manner in which MPLS labels are encoded over various physical and logical networks. It particular, it describes how MPLS can run over SONET, ATM, Frame Relay, or Ethernet.

Chapter 12describes the ATM Adaptation Layer (AAL), which provides support for all higher-layer services, such as signaling, circuit emulation, Frame Relay, and IP. Since MPLS standards are not yet complete in this area, this chapter summarizes the current state and direction of MPLS infrastructure being defined with the aim of supporting multiple services. It describes a particular proposed encapsulation method as an example of the type of protocol that will likely be standardized at some point. We also summarize specific approaches proposed for supporting ATM over MPLS in this chapter.

Chapter 13introduces the higher layers in the user plane in the WAN, the LAN, and the internetwork; control plane signaling and routing for ATM and MPLS. This chapter then introduces the ATM control plane and its AAL and underlying structure. This

DAVID MCDYSAN DAVE PAW