ATM and MPLS theory and application

DAVID MCDYSAN
DAVE PAW

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DOI: 10.1036/0072228377


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CONTENTS
Introduction

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xix

Part I
Overview, Introduction, Background, Motivation, and Standards
▼1

▼2

Introduction to ATM and MPLS and Overview of the Book . . . . . . . . . . . .

3

Overview of This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6
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Background and Motivation for ATM and MPLS Networking . . . . . . . . . . .

13

A Brief History of Communications . . . . . . . . . . . . . . . . . . . .
Recurring Trends in Encoding and Relaying . . . . . . . . . . .
Data Networking: Enabling Computers to Communicate. . . . .
Changing Organizations of People and Networks . . . . . . . .
Defining the Demand for Communications . . . . . . . . . . . . . . . .
Residential and Commercial Users . . . . . . . . . . . . . . . . .
Applications and Networks Change Faster Than Behavior . . .
Geographical Aspects of Networking . . . . . . . . . . . . . . .
The End Result: Tremendous Internet and Data Traffic Growth

Technology Trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Processor and Memory Cost Trends: Moore’s Law . . . . . . . .
Distributed Computer Communications Protocols . . . . . . . .
Modernization of Transmission Infrastructures . . . . . . . . . .
Faster and Farther, but Never Free . . . . . . . . . . . . . . . . .

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Copyright 2002 by The McGraw-Hill Companies, Inc. Click Here for Terms of Use.

iii


iv

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

▼3

The Accelerating Bandwidth Principle . . . . . . . . . . . . . . . . .
Worldwide Cooperation for Standards . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

25

ATM- and MPLS-Related Standards Bodies . . . . .
International Telecommunications Union (ITU)
ATM Forum . . . . . . . . . . . . . . . . . . . .
Internet Engineering Task Force (IETF) . . . .
Frame Relay Forum . . . . . . . . . . . . . . . .
MPLS Forum . . . . . . . . . . . . . . . . . . .
DSL Forum . . . . . . . . . . . . . . . . . . . .
Other B-ISDN/ATM Standards Bodies . . . .
Creating Standards: The Players . . . . . . . . . . . .
Vendors . . . . . . . . . . . . . . . . . . . . . .
Users . . . . . . . . . . . . . . . . . . . . . . . .
Network Service Providers . . . . . . . . . . .
Creating Standards: The Process . . . . . . . . . . . .
Charter and Work Plan . . . . . . . . . . . . . .
Meetings and Contributions . . . . . . . . . . .
Drafting and Review . . . . . . . . . . . . . . .

Approval and Consensus . . . . . . . . . . . .
User Acceptance and Interoperability . . . . .
Other Aspects of Standards . . . . . . . . . . . . . . .
Business and Politics . . . . . . . . . . . . . . .
Measures of Success and Proven Approaches .
Predicting the Future of Standardization . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . .

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Part II
Networking and Protocol Fundamentals
▼4

Networks, Circuits, Multiplexing, and Switching

General Network Topologies . . . . . . . . . . . . . . . . . .
Point-to-Point . . . . . . . . . . . . . . . . . . . . . . .
Multipoint and Broadcast . . . . . . . . . . . . . . . .
Star . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ring . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data Communications and Private Lines . . . . . . . . . . .
Simplex, Half-Duplex, and Full-Duplex Transmission
DTE-to-DCE Connections . . . . . . . . . . . . . . . .
Private Lines . . . . . . . . . . . . . . . . . . . . . . . .
Data Transmission Methods . . . . . . . . . . . . . . . . . .
Asynchronous and Synchronous Data Transmission .
Asynchronous Versus Synchronous Transfer Modes .
Principles of Multiplexing and Switching . . . . . . . . . . .
Multiplexing Methods Summarized . . . . . . . . . .
Space Division Multiplexing (SDM) . . . . . . . . . .
Frequency Division Multiplexing (FDM) . . . . . . .
Time Division Multiplexing (TDM) . . . . . . . . . . .
Address or Label Multiplexing . . . . . . . . . . . . .

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Contents

Code Division Multiple Access (CDMA)

Point-to-Point Switching Functions . . .
Point-to-Multipoint Switching Functions
Examples of Multiplexing . . . . . . . .
Examples of Switching . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . .

▼5

▼6

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Basic Protocol Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

69

A Brief History of Packet Switching . . . . . . . . . . . . . . . . .
Early Reasons for Packet Switching . . . . . . . . . . . . .
Principles of Packet Switching . . . . . . . . . . . . . . . .
Darwin’s Theory and Packet-Switching Evolution . . . . .
Basic Protocol Layering Concepts . . . . . . . . . . . . . . . . . .
Open Systems Interconnection Reference Model . . . . . . . . . .
Layers of the OSI Reference Model . . . . . . . . . . . . . . . . .
Physical Layer . . . . . . . . . . . . . . . . . . . . . . . . . .
Data Link Layer . . . . . . . . . . . . . . . . . . . . . . . . .
Network Layer . . . . . . . . . . . . . . . . . . . . . . . . .
Transport Layer . . . . . . . . . . . . . . . . . . . . . . . . .
Session Layer . . . . . . . . . . . . . . . . . . . . . . . . . .
Presentation Layer . . . . . . . . . . . . . . . . . . . . . . .

Application Layer . . . . . . . . . . . . . . . . . . . . . . . .
Mapping of Generic Devices to OSI Layers . . . . . . . . .
Layered Data Communication Architectures . . . . . . . . . . . .
Internet Protocol (IP) Architecture . . . . . . . . . . . . . .
IBM’s Systems Network Architecture (SNA) . . . . . . . .
IEEE 802.X Series (LAN/MAN/WAN) . . . . . . . . . . .
Integrated Services Digital Network Protocol Architecture .
Network Service Paradigms . . . . . . . . . . . . . . . . . . . . .
Connection-Oriented Network Service (CONS) . . . . . . .
Connectionless Network Services (CLNS) . . . . . . . . . .
Connection-Oriented Versus Connectionless
Services Analogy . . . . . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Time Division Multiplexing and the Narrowband Integrated Services Digital Network

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Circuit Switching . . . . . . . . . . . . . . . . . . . . . . . . . .
History of Circuit Switching . . . . . . . . . . . . . . . .
Digitized Voice Transmission and Switching . . . . . .
Digital Data Circuit Switching . . . . . . . . . . . . . .
Private-Line Networks . . . . . . . . . . . . . . . . . . . . . .
Private (Leased)–Line Characteristics . . . . . . . . . .
Private-Line Networking . . . . . . . . . . . . . . . . .
Permanent Versus Switched Circuits . . . . . . . . . . .
Digital Time Division Multiplexing (TDM) . . . . . . . . . . .
Plesiochronous Digital Hierarchy (PDH) . . . . . . . .
SONET and the Synchronous Digital Hierarchy (SDH)
Basic SONET Frame Format . . . . . . . . . . . . . . . .
Basics and History of Narrowband ISDN (N-ISDN) . . . . . .
Narrowband ISDN Basics . . . . . . . . . . . . . . . . .
BRI and PRI Service and Protocol Structures . . . . . .
ISDN D-Channel Signaling . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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v


vi

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

▼7

▼8

Connection-Oriented Protocols—X.25 and Frame Relay . . . . . . . . . . . . .

121

Packet Switching . . . . . . . . . . . . . . . . . . . . . . . . . . .
Origins of X.25 . . . . . . . . . . . . . . . . . . . . . . . .
Protocol Structure . . . . . . . . . . . . . . . . . . . . . . .

Networking Context . . . . . . . . . . . . . . . . . . . . .
SDLC, HDLC, and X.25’s Link Layer Protocol . . . . . .
Packet Layer Format and Protocol . . . . . . . . . . . . .
Control Functions . . . . . . . . . . . . . . . . . . . . . . .
Example of X.25 Operation . . . . . . . . . . . . . . . . .
Traffic and Congestion Control Aspects of X.25 . . . . . .
Service Aspects of X.25 . . . . . . . . . . . . . . . . . . . .
Frame Relay—Overview and User Plane . . . . . . . . . . . . .
Origins of Frame Relay . . . . . . . . . . . . . . . . . . . .
Frame Relay Protocol Structure . . . . . . . . . . . . . . .
Frame Relay Networking Context . . . . . . . . . . . . .
Frame Format . . . . . . . . . . . . . . . . . . . . . . . . .
Frame Relay Functions . . . . . . . . . . . . . . . . . . . .
Example of Frame Relay Operation . . . . . . . . . . . . .
Traffic and Congestion Control Aspects of Frame Relay .
Service Aspects of Frame Relay . . . . . . . . . . . . . . .
Frame Relay—Control Plane . . . . . . . . . . . . . . . . . . . .
Frame Relay Control Protocol Networking Context . . .
Frame Relay Standards and Specifications . . . . . . . . .
Frame Relay PVC Status Signaling . . . . . . . . . . . . .
Frame Relay PVC Status Signaling Example . . . . . . .
Multilink Frame Relay . . . . . . . . . . . . . . . . . . . .
Frame Relay Service Level Agreements (SLAs) . . . . . .
Frame Relay Operations, Administration, and Maintenance
Frame Relay Fragmentation and Compression . . . . . .
Frame Relay Privacy . . . . . . . . . . . . . . . . . . . . .
Frame Relay Switched Virtual Connections (SVCs) . . .
Example of Frame Relay SVC Operation . . . . . . . . . .
Frame Relay Signaling Message Information Elements .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Connectionless Protocols—IP and SMDS . . . . . . . . . . . . . . . . . . . .

175

The Internet Protocol SUITE, TCP/IP . . . . . . . . . .
Origins of TCP/IP . . . . . . . . . . . . . . . . .
TCP/IP Protocol Structure . . . . . . . . . . . . .
TCP/IP Networking Context . . . . . . . . . . .
Generic Link Layer Protocols for IP . . . . . . .
IP Version 4 (IPv4) Packet Format . . . . . . . .
Internet Protocol (IP) Addressing . . . . . . . . .
Next Generation IP—IPv6 . . . . . . . . . . . . .
Quality of Service in IP Networks . . . . . . . .
Transmission Control Protocol (TCP) . . . . . .
User Datagram Protocol (UDP) . . . . . . . . . .
Real-Time Transport Protocol (RTP) . . . . . . .
Service Aspects of TCP/IP . . . . . . . . . . . . .
Switched Multimegabit Data Service (SMDS) . . . . .
Origins of SMDS . . . . . . . . . . . . . . . . . .
SMDS/IEEE 802.6 Protocol Structure . . . . . .
SMDS/802.6 Protocol Data Unit (PDU) Formats

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Contents

DQDB and SMDS Operation . . . . . . . . . . . . . . . . . .
Example of SMDS over DQDB Operation . . . . . . . . . . .
Traffic and Congestion Control Aspects of DQDB and SMDS
Service Aspects of SMDS . . . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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202
204
204
205
206

LANS, Bridging, and Routing . . . . . . . . . . . . . . . . . . . . . . . . . . .

207

Bridging, Routing, and Internetworking . . . . . . . . . . .
Basic Terminology . . . . . . . . . . . . . . . . . . .
Address Assignment and Resolution . . . . . . . . .
Routing, Restoration, and Reconfiguration . . . . .
IEEE Local Area Networking (LAN) Standards . . . . . .
Layered LAN Protocol Model . . . . . . . . . . . . .
Typical LLC and MAC Sublayer Implementations .
The Logical Link Control (LLC) Sublayer . . . . . .

The Media Access Control (MAC) Sublayer . . . . .
Ethernet and the CSMA/CD 802.3 MAC Sublayer .
Ethernet User Priority and VLANs . . . . . . . . . .
Token Ring . . . . . . . . . . . . . . . . . . . . . . .
100 Mbps Fast Ethernet . . . . . . . . . . . . . . . .
100VG-AnyLAN . . . . . . . . . . . . . . . . . . . .
Gigabit and 10 Gbps Ethernet . . . . . . . . . . . . .
Fiber Distributed Data Interface (FDDI) . . . . . . . . . . .
Basic Fiber Distributed Data Interface (FDDI) . . . .
Hybrid Ring Control (FDDI-II) . . . . . . . . . . . .
Bridging Concepts, Systems, and Protocols . . . . . . . . .
Bridging Context . . . . . . . . . . . . . . . . . . . .
A Taxonomy of Bridges . . . . . . . . . . . . . . . .
Spanning Tree Protocol . . . . . . . . . . . . . . . .
Source Routing Protocol . . . . . . . . . . . . . . . .
Bridge Network Design . . . . . . . . . . . . . . . .
Routing Concepts, Systems, and Protocols . . . . . . . . .
Packet-Forwarding and Routing Protocol Functions
Link-State Routing Protocols Defined . . . . . . . .
Routing and Logical IP Subnetworks (LISs) . . . . .
Address Resolution Protocol (ARP) . . . . . . . . .
Bridging and Routing Systems Design . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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208
208
210
211

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219
220
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231
232
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235
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242
245
247
249

▼ 10 Introduction to ATM and MPLS . . . . . . . . . . . . . . . . . . . . . . . . . .

253

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Part III
Foundations of ATM and MPLS: Protocol and Structure
Introduction to ATM and B-ISDN . . . .
B-ISDN Protocol Reference Model
B-ISDN Architecture . . . . . . . .
Overview of the Application of ATM . .
ATM as a Technology . . . . . . .
ATM as a Protocol . . . . . . . . .
ATM as an Interface . . . . . . . .
ATM as Integrated Access . . . . .

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254
254
255
256
257
257
258
259

vii


viii

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

ATM as an End-to-End Service . . . . . . . . . . .
ATM as a Scalable Infrastructure . . . . . . . . . .
Origins of MPLS: Reinventing IP over ATM . . . . . . .
Ipsilon’s IP Switching . . . . . . . . . . . . . . . .

Toshiba’s Cell Switching Router (CSR) . . . . . . .
Cisco’s Tag Switching . . . . . . . . . . . . . . . .
IBM’s Aggregate Route-Based IP Switching (ARIS)
Early IETF Multiprotocol Label Switching (MPLS)
Introduction to MPLS . . . . . . . . . . . . . . . . . . . .
Traffic Engineering of IP Networks . . . . . . . . .
Network-Based IP VPN using MPLS Tunneling .
Multi-Service MPLS Tunneling . . . . . . . . . . .
Considerations in the Choice of Cells Versus Frames . .
Effect of Link Speed on Packet Performance . . . .
Rationale for the Choice of ATM Cell Size . . . . .
Hardware Price-Performance Trade-offs . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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261
261
263
265
267
267
270
272
274
275
276
276
277
277
278
279
280

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

281

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Overview of Physical, ATM, and AAL Layer Functions . . . .
B-ISDN Protocol Layer Structure . . . . . . . . . . . . . .
Hardware and Software Implementations of B-ISDN Layers
ATM Physical Layer . . . . . . . . . . . . . . . . . . . . . . . . .
Physical Medium–Dependent Sublayer . . . . . . . . . .
Transmission Convergence (TC) Sublayer . . . . . . . . .
TC Header Error Check (HEC) Functions . . . . . . . . .
TC Cell Rate Decoupling . . . . . . . . . . . . . . . . . . .
Inverse Multiplexing over ATM . . . . . . . . . . . . . .
xDSL Physical Layer for ATM . . . . . . . . . . . . . . . .
ATM Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ATM UNI and NNI Defined . . . . . . . . . . . . . . . . .
ATM Virtual Paths and Channels (VPs and VCs) . . . . .
The ATM Cell . . . . . . . . . . . . . . . . . . . . . . . . .
ATM-Layer QoS and Service Categories . . . . . . . . . .
Multiprotocol Label Switching (MPLS) . . . . . . . . . . . . . .
IP over MPLS Architecture and Terminology . . . . . . .
MPLS Forwarding Operations . . . . . . . . . . . . . . .
Example of MPLS Forwarding of IP Packets . . . . . . .
MPLS Encapsulation Standards . . . . . . . . . . . . . . . . . .
MPLS Shim Header . . . . . . . . . . . . . . . . . . . . . .
MPLS over ATM . . . . . . . . . . . . . . . . . . . . . . .
MPLS over Frame Relay . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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319

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▼ 12 ATM Adaptation and MPLS Tunneling Protocols . . . . . . . . . . . . . . . . .
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282
283
284
285
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287
288
290
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292

296
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306
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312
312
312
315
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318

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ATM Adaptation Layer (AAL) . . . . . . . . . . . . . . . . .
ATM Adaptation Layer (AAL)—Protocol Model . . .
AAL Protocol Structure Defined . . . . . . . . . . . .
Key AAL Attributes . . . . . . . . . . . . . . . . . . .
ATM Adaptation Layer 1 (AAL1) . . . . . . . . . . . . . . .
AAL1 Segmentation and Reassembly (SAR) Sublayer
AAL1 Convergence Sublayer Functions . . . . . . . .

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320
320
321
322
323
324
325


Contents

Structured Data Transfer (SDT) Convergence Sublayer
Unstructured Mode Convergence Sublayer . . . . . . .
AAL1 Clock Recovery Methods . . . . . . . . . . . . . .
ATM Adaptation Layer 2 (AAL2) . . . . . . . . . . . . . . . .
AAL2 Protocol Structure and PDU Formats . . . . . . .
Example of AAL2 Operation . . . . . . . . . . . . . . .
ATM Adaptation Layer 3/4 (AAL3/4) . . . . . . . . . . . . .
AAL3/4 SAR Sublayer . . . . . . . . . . . . . . . . . . .

AAL3/4 CPCS Sublayer . . . . . . . . . . . . . . . . . .
Example of AAL3/4 Operation . . . . . . . . . . . . . .
AAL3/4 Multiplexing Example . . . . . . . . . . . . . .
ATM Adaptation Layer 5 (AAL5) . . . . . . . . . . . . . . . .
AAL5 Segmentation and Reassembly (SAR) Sublayer .
AAL5 Common Part Convergence (CPCS) Sublayer . .
Example of AAL5 Operation . . . . . . . . . . . . . . .
AAL5 Multiplexing Example . . . . . . . . . . . . . . .
Multi-Service Tunneling over MPLS (and Other Protocols) .
General Concept of Protocol Tunneling . . . . . . . . . . . . .
ATM Forum’s ATM over MPLS Network Interworking . . .
IETF Pseudo Wire Emulation Edge to Edge (PWE3) . .
“Martini” Multi-Service Encapsulation . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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327
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330
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337
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342

342
343
344
346
346
348
350
351
352

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

353

Overview of Higher-Layer ATM and MPLS Protocols . . . . . .
Circuit Emulation Voice, Video, and WAN Data Protocols
Local Area Networking and IP-Based Applications . . . .
ATM Service Category and AAL Support for Applications
Overview of ATM and MPLS Control Plane Protocols . . . . . .
Generic Control Plane Functions . . . . . . . . . . . . . . .
Switched and Permanent ATM Virtual Connections . . . .
ATM Control Plane Protocols . . . . . . . . . . . . . . . . .
MPLS Control Plane Protocols . . . . . . . . . . . . . . . .
ATM Control Plane Structure and AAL . . . . . . . . . . . . . . .
ITU-T B-ISDN Signaling Protocols . . . . . . . . . . . . . .
Types of Signaling Channel Association . . . . . . . . . . .
Layered Signaling AAL Model . . . . . . . . . . . . . . . .
Service Specific Coordination Function (SSCF) . . . . . . .
Service Specific Connection-Oriented Protocol (SSCOP) . .
ATM User-Network Interface (UNI) Signaling . . . . . . . . . . .

Base Signaling Functions: Q.2931 and UNI 3.1 . . . . . . .
ATM Forum UNI Signaling 4.0 and ITU-T Standards . . .
ATM Forum UNI Signaling 4.1 and ITU-T Standards . . .
UNI 4.1 Signaling Message Types . . . . . . . . . . . . . .
Signaling Message Information Elements . . . . . . . . . .
Examples of ATM Signaling Procedures . . . . . . . . . . .
ATM Control Plane Addressing . . . . . . . . . . . . . . . . . . .
Control Plane Addressing Levels . . . . . . . . . . . . . . .
ATM Level Addressing . . . . . . . . . . . . . . . . . . . .
ATM Addressing Formats . . . . . . . . . . . . . . . . . . .
ATM Forum ATM End System Address (AESA) Formats .
Group Addresses and Anycast . . . . . . . . . . . . . . . .

354
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ix


x

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

ILMI Address Registration . .
Bi-Level Addressing . . . . . .
ATM Name Service (ANS) . . .
Review . . . . . . . . . . . . . . . . .

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383
384
384
385

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

387

MPLS Control Plane Architecture . . . . . . . . . . . . . . .
MPLS Control and Forwarding Plane Model . . . . .
Motivation for Constraint-Based Routing . . . . . . .
MPLS Label Distribution Control Protocol Attributes .
MPLS Label Distribution Signaling Protocols . . . . . . . .
Label Distribution Protocol (LDP) . . . . . . . . . . .
RSVP Traffic Engineering (RSVP-TE) . . . . . . . . . .
Constraint-Based Routing LDP (CR-LDP) Extensions
Use of BGP for Label Distribution . . . . . . . . . . .
IGP Traffic Engineering Extensions: OSPF and IS-IS . . . . . .
General Modifications for Traffic Engineering . . . .
Specific Modifications for IS-IS TE . . . . . . . . . . .
Specific Modifications for OSPF-TE . . . . . . . . . .

Open Issues and Challenges Ahead . . . . . . . . . .
Example Applications of MPLS in IP Networks . . . . . . .
Traffic Engineering in an IP Backbone . . . . . . . . .
Label Distribution in Support of Other Services . . .
MPLS Connectivity Across Multiple Providers . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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388
388
389
391
397
397
400
404
405
407
407
408
408
409
409
409
411
412
413

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

415

Interim Interswitch Signaling Protocol (IISP) . . . . . . . . . . . . . .
Private Network-Network Interface (PNNI) . . . . . . . . . . . . . .
Architecture and Requirements . . . . . . . . . . . . . . . . . .
Network Addressing Philosophy . . . . . . . . . . . . . . . . .
A Tale of Two Protocols . . . . . . . . . . . . . . . . . . . . . .
PNNI Routing Hierarchy and Topology Aggregation . . . . .
Beyond Connectivity to Quality and Bandwidth . . . . . . . .
Soft Permanent Virtual Connections (SPVCs) . . . . . . . . . .
Minimum Interoperable PNNI 1.1 Subset . . . . . . . . . . . .
Broadband InterCarrier Interface (B-ICI) . . . . . . . . . . . . . . . .
B-ISDN User Services Part (BISUP) . . . . . . . . . . . . . . . . . . .
B-ICI’s Replacement: ATM Inter-Network Interface (AINI) . . . . .
Extended PNNI and AINI Routing and Signaling Capabilities
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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416
416
417
418
419
420
427
431
432
433
433
434
436
439

▼ 16 Enabling Voice, TDM, and Video Over ATM and MPLS . . . . . . . . . . . . .

443

Part IV
ATM and MPLS Support for Networking Applications
Packet Voice Networking . . . . . . . .
General Network Architecture .
Media Gateway Functions . . . .
Packet Voice Encoding Standards
Quality Considerations . . . . . .

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444
445
446
446
448

Contents

Voice Trunking Using ATM and MPLS . . . . . . . . .
Voice over ATM (VoATM) Trunking . . . . . . .
Voice over MPLS (VoMPLS) Trunking . . . . . .
Broadband Local Loop Emulation Using AAL2 . . . .
Circuit Emulation Using ATM and MPLS . . . . . . .
AAL1-Based Circuit Emulation Service (CES) . .
Circuit Emulation over MPLS . . . . . . . . . . .
Video over ATM and Packet Networks . . . . . . . . .
Commonly Used Video Coding Standards . . .
MPEG-2 Video Over ATM and Packet Networks
QoS Considerations Related to Video . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . .

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449
450
457
459
463
463
466
467
467
468
471
472

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

473

Interworking, Access, and Trunking . . . . . . . . . . . . . . . .
Overview of Frame Relay/ATM Interworking . . . . . . . . . .
Frame Relay/ATM Network Interworking . . . . . . . . . . . .
FR Service-Specific Convergence Sublayer (FR-SSCS) . .
Status Signaling Conversion . . . . . . . . . . . . . . . . .
Congestion Control and Traffic Parameter Mapping . . .
Frame Relay/ATM Service Interworking . . . . . . . . . . . . .
Status Signaling Interworking . . . . . . . . . . . . . . . .

Address Resolution Protocol Interworking . . . . . . . .
FR/ATM SVC Service Interworking . . . . . . . . . . . .
FR/ATM Interworking Applied . . . . . . . . . . . . . .
ATM Access to SMDS . . . . . . . . . . . . . . . . . . . . . . . .
Frame-Based Interfaces Supporting ATM . . . . . . . . . . . . .
ATM Data Exchange Interface (DXI) . . . . . . . . . . . .
Frame-Based User-Network Interface (FUNI) . . . . . . .
Frame-Based ATM over SONET/SDH Transport (FAST)
Frame-Based ATM Transport over Ethernet (FATE) . . .
MPLS-Based Support for Link Layer Protocols . . . . . . . . . .
Pseudo-Wire and Service Emulation Considerations . . .
Martini Encapsulation and Transport of FR, AAL5, ATM,
and HDLC . . . . . . . . . . . . . . . . . . . . . . . . .
FR over MPLS Network Interworking . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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500

502
503

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

505

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474

477
478
479
480
480
481
482
483
484
486
488
489
489
493
496
497
498
499

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Multiprotocol Encapsulation over AAL5 . . . . . . . . . . . .
Protocol Encapsulation . . . . . . . . . . . . . . . . . . .
VC-Based Multiplexing . . . . . . . . . . . . . . . . . .
Considerations in the Selection of Multiplexing Method

ATM Forum LAN Emulation (LANE) . . . . . . . . . . . . . .
Hardware and Software in an Emulated LAN . . . . .
LANE Components and Connection Types . . . . . . .
Summary of LANE Operation . . . . . . . . . . . . . . .
LANE and Spanning Tree . . . . . . . . . . . . . . . . .
LANE Implementation Considerations . . . . . . . . .
Ethernet over MPLS . . . . . . . . . . . . . . . . . . . . . . . .
Martini Encapsulation of Ethernet over MPLS . . . . .
Virtual Private LAN Service (VPLS) . . . . . . . . . . .

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506
506
508
510
511
511
514
514
518
519
520
520
521

xi

xii

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

VPLS and Access to the Internet . . . . . . . . . . . . . .
Interworking Network Layer Protocols over MPLS . . .
Metropolitan and Wide Area Ethernet over
MPLS Networking . . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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525
526

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528
530

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

531

IP over ATM Virtual Private Networks . . . . . . . . . . . . . .
Classical IP over ATM . . . . . . . . . . . . . . . . . . . .

Multiprotocol over ATM (MPOA) . . . . . . . . . . . . .
IP Multicast over ATM . . . . . . . . . . . . . . . . . . . .
IP Virtual Private Networks (VPN) over MPLS or IP Tunnels .
General Virtual Private Network (VPN) Terminology
and Concepts . . . . . . . . . . . . . . . . . . . . . . .
Network-Based IP VPN Concepts . . . . . . . . . . . . .
Aggregated Routing Network-Based VPNs Using Tunnels
Virtual Router Network-Based VPNs using Tunnels . . .
Considerations and Trade-offs with
Network-Based IP VPNs . . . . . . . . . . . . . . . . .
Considerations Regarding Choice of Tunnel Type . . . .
VPN Representations and Configuration Complexity . .
IP Path Maximum Transfer Unit (MTU) Discovery . . . . . . .
MTU Path Discovery over AAL5 . . . . . . . . . . . . . .
MTU Path Discovery over MPLS . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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533
533
537
542
545

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545

548
550
554

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556
557
558
560
560
561
562

Part V
Quality of Service, Traffic Management, and Congestion Control
▼ 20 The Traffic Contract and Quality of Service (QoS) . . . . . . . . . . . . . . . .
The Traffic Contract . . . . . . . . . . . . . . . . . . . . . .
Reference Models . . . . . . . . . . . . . . . . . . . . . . .
Generic Allocation of Impairments Model . . . . . .
ATM Equivalent Terminal Model . . . . . . . . . . .
Diffserv Per-Hop and Per-Domain Behavior Models
Quality Of Service . . . . . . . . . . . . . . . . . . . . . . .
Application QoS Requirements . . . . . . . . . . . .
ATM QoS Parameters . . . . . . . . . . . . . . . . .
IP Performance Metrics (IPPM) . . . . . . . . . . . .
Traffic Parameters and Conformance Definitions . . . . .
ATM Traffic Descriptor . . . . . . . . . . . . . . . .
IP Traffic Descriptor . . . . . . . . . . . . . . . . . .
ATM Conformance Definitions . . . . . . . . . . . .
IP Traffic Conformance Definitions . . . . . . . . . .
Classes of Service . . . . . . . . . . . . . . . . . . . . . . .
ATM Forum QoS Classes and Service Categories . .
ITU-T ATM QoS Classes . . . . . . . . . . . . . . . .
Mapping Between ATM Forum and ITU-T
QoS Definitions . . . . . . . . . . . . . . . . . . .
Diffserv Per-Hop Behaviors (PHBs) . . . . . . . . .
MPLS Support for Diffserv . . . . . . . . . . . . . .

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566
567
567
568
569
571
571
573
578
579
579
582
583
585
586
586
588

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591
594
595


Contents

Comparison of ATM and IP QoS and TrafficParameters . . .
ATM Service Categories Optimized for Packet Switching . .
Guaranteed Frame Rate (GFR) . . . . . . . . . . . . . .
Switch Modifications to Support GFR . . . . . . . . . .
UBR with BSC and MDCR . . . . . . . . . . . . . . . . .
Use of Differentiated UBR to Support Diffserv . . . . .
Use of Differentiated UBR to Support IEEE 802.x . . . .
UBR Service Category with Optional MDCR Parameter
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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596
597

597
601
603
604
605
605
607

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

609

Achieving Conformance . . . . . . . . . . . . . . . . . .
Checking Conformance: Policing . . . . . . . . . . . . .
ATM Policing . . . . . . . . . . . . . . . . . . . . .
Examples of Leaky Bucket Policing . . . . . . . . .
Generic Cell Rate Algorithm (GCRA) and
Virtual Scheduling . . . . . . . . . . . . . . . . .
IP and MPLS Policing . . . . . . . . . . . . . . . .
Ensuring Conformance: Shaping . . . . . . . . . . . . . .
Overview of Possible Shaping Methods . . . . . .
Leaky Bucket Buffering . . . . . . . . . . . . . . .
Token Bucket Shaping . . . . . . . . . . . . . . . .
Delivering QoS: Prioritization, Queuing, and Scheduling
Prioritized Queuing and Scheduling . . . . . . . .
Priority Discard Thresholds . . . . . . . . . . . . .
Performance Implications of Priority Control . . .
Overview of Weighted Scheduling Algorithms . .
Meeting the Traffic Contract: Resource Management . .
Admission Control . . . . . . . . . . . . . . . . . .

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

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610
612
613
613

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619

620
624
625
626
627
630
630
631
632
633
634
634
638
640

▼ 22 Congestion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

641

Congestion: A Familiar Phenomenon . . . . . . . .
The Nature of Congestion . . . . . . . . . . .
Busy Seasons, Days, and Hours . . . . . . . .
Impact of Congestion . . . . . . . . . . . . . .
Examples of Congestion in a Network . . . .
Congestion Control: A Range of Solutions . . . . .
Open- and Closed-Loop Congestion Control
Impact of Congestion on Performance . . . .
Categorization of Congestion Control Approaches
Congestion Management . . . . . . . . . . . . . . .
Resource Allocation . . . . . . . . . . . . . .

Network Engineering . . . . . . . . . . . . .
Congestion Avoidance . . . . . . . . . . . . . . . .
Congestion Indication . . . . . . . . . . . . .
Policing and Tagging . . . . . . . . . . . . . .
Connection Blocking . . . . . . . . . . . . . .
Closed-Loop Flow Control . . . . . . . . . . . . . .
Generic Closed-Loop Flow Control Methods
ATM Generic Flow Control (GFC) . . . . . .

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642
642
643
644
644
645
645
646
649
652
652
652
653
653
654
654
654
655
656

xiii

xiv

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

Available Bit Rate . . . . . . . . . . . . . .
The Great Rate Versus Credit Debate . . .
Congestion Recovery . . . . . . . . . . . . . . .
Selective Discard . . . . . . . . . . . . . .
Early/Partial Packet Discard (EPD/PPD)
Dynamic Usage Parameter Control (UPC)
Disconnection and/or Rerouting . . . . .
Operational Procedures . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . .

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657
659
667
667
668
670
670
671
671

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

675

Philosophy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Communications Channel Model . . . . . . . . . . . . . . .
Deterministic Versus Random Modeling . . . . . . . . . .
Probability Theory . . . . . . . . . . . . . . . . . . . . . . . . . . .
Randomness in Communications Networks . . . . . . . . .
Random Trials and Bernoulli Processes . . . . . . . . . . .
The Normal/Gaussian Distribution . . . . . . . . . . . . .
Common Digital Signals and Their Spectra . . . . . . . . . . . . .
The Telegraph Pulse: Binary On/Off Keying . . . . . . . .
A Better Way: Pulse Shaping . . . . . . . . . . . . . . . . .
Pushing the Envelope: Quadrature Amplitude Modulation
Error Models and Channel Capacity . . . . . . . . . . . . . . . . .
Typical Communications Channel Error Models . . . . . .
Shannon’s Channel Capacity . . . . . . . . . . . . . . . . .
Error Performance of Common Modulation Methods . . .
Error-Detecting and -Correcting Codes . . . . . . . . . . . . . . .
Simple Parity Check Schemes . . . . . . . . . . . . . . . . .
Cyclical Redundancy Check (CRC) Codes . . . . . . . . . .
Performance of ATM’s HEC . . . . . . . . . . . . . . . . . .
Undetected Error Performance of HDLC and AAL5 . . . .
Data Compression . . . . . . . . . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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676
676
677
677
677
678
678
679
680
681
681
685
685

686
688
689
689
690
691
694
694
696

▼ 24 Traffic Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

697

Philosophy . . . . . . . . . . . . . . . . . . . . . . . .
Source Model Traffic Parameter Characteristics
Modeling Accuracy . . . . . . . . . . . . . . . .
Overview of Queuing Theory . . . . . . . . . . . . .
General Source Model Parameters . . . . . . .
Poisson Arrivals and Markov Processes . . . .
Queuing System Models . . . . . . . . . . . . .
Call Attempt Rates, Blocking, and Queuing . . . . .
Statistical Model for Call Attempts . . . . . . .
Erlang’s Blocked Calls Cleared Formula . . . .
Erlang’s Blocked Calls Held Formula . . . . .
Performance of Buffering Methods . . . . . . . . . .
Input Versus Output Queuing Performance . .

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698
698
699
699
699
702
705
708
708
709
711
713
713


Contents

Output Buffer Overflow Probability
Shared Buffer Performance . . . . .
Deterministic Constant Rate Performance
Equivalent Capacity . . . . . . . . . . . . .
Fluid Flow Approximation . . . . .
Statistical Multiplex Gain Model . .
Equivalent Capacity Approximation
Priority Queuing Performance . . . . . . .
Review . . . . . . . . . . . . . . . . . . . .

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714
716
718
720
721
722
726
728
730

▼ 25 Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

731

Impacts of Delay, Loss, and Delay Variation . . . . . . . . . .
Impact of Delay . . . . . . . . . . . . . . . . . . . . . . .
Impact of Loss . . . . . . . . . . . . . . . . . . . . . . . .
Impact of Delay Variation . . . . . . . . . . . . . . . . .
TCP Performance Considerations . . . . . . . . . . . . . . . .
TCP Window Size Impact on Throughput . . . . . . . .
TCP over ATM: UBR and ABR . . . . . . . . . . . . . .
TCP/IP Performance in a Congested Scenario . . . . .
Voice and Data Integration . . . . . . . . . . . . . . . .
Voice Traffic Model . . . . . . . . . . . . . . . . . . . . .
Statistically Multiplexing Voice Conversations . . . . .
Voice/Data Integration Savings . . . . . . . . . . . . . .
Overview of the Network Planning and Design Process . . .
Network Design Approaches and Modeling Philosophy
Measuring Traffic and Performance Data . . . . . . . .

Analyzing and Simulating Candidate Networks
and Technology . . . . . . . . . . . . . . . . . . . . .
Practice Makes Perfect . . . . . . . . . . . . . . . . . . .
Network Design and Modeling Tools . . . . . . . . . . . . . .
Design Tool Graphical User Interface (GUI) . . . . . . .
Specifying Design Scenarios . . . . . . . . . . . . . . . .
Modeling Network-Specific Capabilities . . . . . . . . .
Displaying and Comparing Results . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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732
732
735
738
742
742
742
743
745
745
746
747
748
749
750

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751
752
753
753
754
755
755
756

▼ 26 Operational Philosophy and Network Management Architectures . . . . . . . .

759

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Part VII
Operations and Network Management for ATM and MPLS
OAM&P Philosophy . . . . . . . . . . . . . . . . . . . . . . . .
Administration . . . . . . . . . . . . . . . . . . . . . . .
Provisioning . . . . . . . . . . . . . . . . . . . . . . . . .
Operations . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . .
Unique Challenges Created by ATM . . . . . . . . . . .
Unique Challenges Created by MPLS . . . . . . . . . .
Network Management Architectures . . . . . . . . . . . . . .
Centralized Versus Distributed Network Management
OSI Network Management Functional Model . . . . . .

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760
760
761
762
762
763
763
764
764
765

xv


xvi

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

ITU Telecommunications Management Network (TMN)
ITU-T Generic Transport Network Architecture . . . . .
ATM Forum Network Management Architecture . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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766
769
772
773

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

775

Network Management Protocols . . . . . . . . . . . . . . . . . . . .
IETF Simple Network Management Protocol (SNMP) . . . .
ITU-T Common Management Interface Protocol (CMIP) . .
Proprietary Network Management Protocols . . . . . . . . .
Considerations on Choice of Network Management Protocol
ATM Management Information Bases (MIBs) . . . . . . . . . . . .
ATM Forum Integrated Local Management Interface (ILMI)
IETF AToM MIBs . . . . . . . . . . . . . . . . . . . . . . . . .
Other ATM MIBs . . . . . . . . . . . . . . . . . . . . . . . . .
MPLS Management Information Bases (MIBs) . . . . . . . . . . . .
Label Switch Router (LSR) and Related MIBs . . . . . . . . .
Traffic Engineering (TE) MIBs . . . . . . . . . . . . . . . . . .
Multiservice PPVPN and PWE3 MIBs . . . . . . . . . . . . .
IP-Based Management Tools for MPLS . . . . . . . . . . . . . . . .
ICMP PING and Traceroute . . . . . . . . . . . . . . . . . . .
Vendor-Proprietary ICMP Extensions for MPLS . . . . . . .
IETF Direction for IP-Based MPLS Management . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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776
776
780
781
782
782
783
786
787
787
788
789
789

790
790
791
792
793

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

795

ATM OAM Flow Reference Architecture . . . . . . .
ATM OAM Cell Formats . . . . . . . . . . . . . . . .
ATM OAM Fault Management . . . . . . . . . . . . .
AIS and RDI Theory and Operation . . . . . .
Loopback Operation and Diagnostic Usage . .
Continuity Check (CC) . . . . . . . . . . . . . .
ATM Protection Switching . . . . . . . . . . . . . . .
ATM Performance Specification and Measurement .
Network Performance and Quality of Service .
ATM Performance Measurement (PM) . . . . .
NP/QoS Parameter Estimation . . . . . . . . .
MPLS OAM Status and Direction . . . . . . . . . . .
Overview of ITU Direction for MPLS OAM . .
MPLS Protection Switching and Fast Rerouting
Review . . . . . . . . . . . . . . . . . . . . . . . . . .

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796
798

800
800
802
806
806
810
810
810
814
819
819
820
820

Part VIII
Design Considerations and Future Directions Involving ATM and MPLS
▼ 29 Design Considerations for ATM and MPLS Networks . . . . . . . . . . . . . .
Efficiency Analysis . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Emulation Efficiency . . . . . . . . . . . . . . . .
Packetized Voice Efficiency . . . . . . . . . . . . . . . .
Efficiency of Cells Versus Frames for Packet Switching

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825
826
826

828
829


Contents

IP/ATM, IP/MPLS, and IP/SONET Efficiency . . . . . .
Packet Video Efficiency . . . . . . . . . . . . . . . . . . .
Multiservice Efficiency Comparison . . . . . . . . . . . .
Scalability Analysis . . . . . . . . . . . . . . . . . . . . . . . . .
Addressing and Hierarchy . . . . . . . . . . . . . . . . . .
Supported User and Routing Table Growth . . . . . . . .
Packet Forwarding and Moore’s Law . . . . . . . . . . .
Connection-Oriented Versus Connectionless Paradigms
Support for a Wide Range of Interfaces and Speeds . . .
Capacity Bottlenecks . . . . . . . . . . . . . . . . . . . . .
Complexity Analysis . . . . . . . . . . . . . . . . . . . . . . . .
To Switch or Not to Switch? An Answer to This Question
Keep It Simple to Succeed . . . . . . . . . . . . . . . . . .
Hardware Is Hard, but Software Is Harder . . . . . . . .
Are QoS and Bandwidth Reservation Really Necessary?
Reliability, Availability, and Stability . . . . . . . . . . . . . . .
Supportability and Operability . . . . . . . . . . . . . . . . . . .
Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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831
834
835
837
837
838
839
840
841
842
842
842
843
843

844
846
847
847
848

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

851

Future Directions and Applications of ATM . . . . . . . . . . . . . .
Multiservice Backbone Network Infrastructure . . . . . . . . .
Convergence and Integrated Access . . . . . . . . . . . . . . .
Lessons Learned from ATM for Multiservice Networking . . . . . .
Don’t Operate at the Per-Flow Level . . . . . . . . . . . . . . .
Use Basic QoS and Traffic Management on Aggregates . . . .
Use Bandwidth Reservation for Constraint-Based Routing . .
Assume a Heterogeneous Underlying Network . . . . . . . .
Future Applications and Directions of MPLS (and IP) . . . . . . . . .
Next Generation Multiservice Network Infrastructure . . . . .
Optical Networking for Scalability . . . . . . . . . . . . . . . .
Generalized MPLS (GMPLS) . . . . . . . . . . . . . . . . . . .
Separation of Forwarding and Control . . . . . . . . . . . . . .
Possible Future of Multiservice Networking . . . . . . . . . . . . . .
What Will Continue the Internet’s Explosive Growth? . . . . .
Will MPLS Become the Ubiquitous Multiservice Network? . .
Will GMPLS Effectively Control Next-Generation Backbones?.
What Will Happen to ATM? . . . . . . . . . . . . . . . . . . . .
Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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852
852
853
853
853
854
854
854
855
855
855
857
860
861
861
862
863
863
863

▼ A Acronyms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . .

865

▼ B References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

881

▼

913

Index

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xvii


ABOUT THE AUTHORS
Dr. David E. McDysan is 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 leadership roles 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 Paw is 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 himself with inter-cultural and inter-religious projects.

ABOUT THE TECHNICAL EDITORS
Richard Carrara is 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 Yao is 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.


INTRODUCTION
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
clearly the killer 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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xix


xx

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

establish efficient switching using locally significant labels. However, ATM was envisioned at the outset with a multi-service mindset that would support any previously-conceived 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, Ethernet, 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


introduction

this information. However, the same cannot be said for MPLS and therefore we outline
the potential directions under investigation at publication time.
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 approach, 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, although 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 up to 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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ATM & MPLS Theory & Application: Foundations of Multi-Service Networking

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 document, 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.


PART I
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

1
Copyright 2002 by The McGraw-Hill Companies, Inc. Click Here for Terms of Use.