Network Convergence
Network Convergence Services, Applications, Transport, and Operations Support Hu Hanrahan University of the Witwatersrand, Johannesburg, South Africa John Wiley & Sons, Ltd
Copyright c 2007 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777 Email (for orders and customer service enquiries): cs-books@wiley.co.uk Visit our Home Page on www.wiley.com All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or emailed to permreq@wiley.co.uk, or faxed to (+44) 1243 770571. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the Publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Other Wiley Editorial Offices John Wiley & Sons Inc., 111 River Street, Hoboken, NJ 07030, USA Jossey-Bass, 989 Market Street, San Francisco, CA 94103-1741, USA Wiley-VCH Verlag GmbH, Boschstr. 12, D-69469 Weinheim, Germany John Wiley & Sons Australia Ltd, 42 McDougall Street, Milton, Queensland 4064, Australia John Wiley & Sons (Asia) Pte Ltd, 2 Clementi Loop #02-01, Jin Xing Distripark, Singapore 129809 John Wiley & Sons Canada Ltd, 6045 Freemont Blvd, Mississauga, ONT, L5R 4J3, Canada Library of Congress Cataloging-in-Publication Data Hanrahan, Hu. Network convergence : services, applications, transport, and operations support / Hu Hanrahan. p. cm. Includes bibliographical references and index. ISBN-13: 978-0-470-02441-6 (cloth : alk. paper) ISBN-10: 0-470-02441-0 (cloth : alk. paper) 1. Convergence (Telecommunication) 2. Internetworking (Telecommunication) 3. Wireless communication systems I. Title. TK5101.H2837 2007 621.382 dc22 2006033562 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 9780470024416 Typeset by the author using L A TEX software. Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire. This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production.
Contents Preface Acknowledgments Conventions Companion Website Abbreviations Principal Graphic Symbols xiii xv xv xvi xvii xxvii 1 Setting the Context for Evolution and Convergence of Networks 1 1.1 Historical Background to Present Networks.............. 2 1.2 Defining Present State Using Reference Models............ 4 1.2.1 Silo Model for Vertically Integrated Networks......... 5 1.2.2 Present State: Fixed and Mobile Networks with IN Overlay. 6 1.2.3 Present State: Data Service in Mobile Networks....... 20 1.2.4 Present State: The Internet................... 23 1.2.5 Present State: Enterprise Networking............. 30 1.2.6 Present State: Switched and Leased-line Services....... 31 1.3 Evolution and Convergence....................... 32 1.3.1 Initial Convergence Examples.................. 33 1.3.2 FeaturesofConvergence... 34 1.4 The Next Generation Network Concept................ 37 1.5 Conclusion................................ 39 2 A Framework for Examining Next Generation Networks 41 2.1 Characteristics of Evolving Networks.................. 41 2.1.1 Proliferation of Terminals and Access Networks........ 43 2.1.2 CoreNetworkTypes... 44 2.1.3 Evolution of Service Architectures............... 45 2.2 Dealing with Complexity......................... 48 2.3 Framework for Evolving Networks................... 51 2.3.1 Layering.............................. 53 2.3.2 Domains.............................. 62 2.3.3 Planes............................... 64 2.3.4 Summary of the NGN Framework............... 67 2.4 Examples of Application of Framework................. 68 2.4.1 Legacy Networks Elements in the Framework......... 68
vi CONTENTS 2.4.2 From Circuit Switch to Softswitch............... 69 2.4.3 Conceptualising Convergence in Layered Model........ 72 2.4.4 Drawing the Boundary of the Regulated Domains...... 74 2.4.5 Digital Video Broadcasting in the Framework......... 74 2.5 Conclusion................................ 76 3 Software Methodologies for Converged Networks and Services 77 3.1 Development of Software Methodologies for ICT........... 78 3.2 Software Processes in the NGN Framework.............. 79 3.2.1 Software Analysis and Design Requirements.......... 80 3.2.2 Functional Entities as Software Elements........... 80 3.2.3 Physical Entities in the Framework............... 82 3.2.4 Specification and Description Requirements.......... 83 3.2.5 Modelling............................. 83 3.3 High-level Analysis and Design Methods................ 84 3.3.1 The Reference Model of Open Distributed Processing............................. 84 3.3.2 Model Driven Architecture................... 88 3.3.3 SDL and MSC.......................... 90 3.3.4 A Legacy System Method: UFM................ 92 3.3.5 Generalising High-level Methods................ 94 3.3.6 Role of Software Architectures................. 95 3.3.7 Software Modelling Notations.................. 95 3.4 Enterprise and Business Modelling Notation.............. 98 3.4.1 Enterprise Language....................... 98 3.4.2 UML Use Case Diagrams.................... 99 3.5 Object and Data Definition Languages................. 100 3.5.1 UML Class and Object Diagrams................ 100 3.5.2 Abstract Syntax Notation One................. 102 3.5.3 Interface Definition Language.................. 106 3.5.4 Classical Telecommunications Protocols............ 107 3.5.5 Method Calls as Application Protocols............. 108 3.5.6 IETFText-basedProtocols... 108 3.5.7 Hypertext Markup Language.................. 111 3.5.8 Extensible Markup Language.................. 111 3.6 Dynamic Modelling Notations...................... 114 3.6.1 Activity, Communication and Robustness Diagrams..... 114 3.6.2 Message Sequence Charts.................... 115 3.6.3 State Diagrams.......................... 119 3.6.4 Connection Models........................ 121 3.7 Component and Interface Notations.................. 122 3.8 Distributed Systems........................... 124 3.8.1 Network Protocol-based Distributed Systems......... 125 3.8.2 Remote Method Invocation................... 125 3.8.3 Web Services Model....................... 126 3.8.4 CORBA-based Systems..................... 127 3.9 Creating a Unified Framework...................... 129
CONTENTS vii 4 An NGN: the Managed Voice over IP Network 131 4.1 Development of Packet Multimedia Standards............. 132 4.2 Requirements on a Managed Voice Network.............. 133 4.3 Properties of Packetised Voice...................... 134 4.3.1 Key Properties of Speech.................... 134 4.3.2 Digitising Speech......................... 135 4.3.3 Reducing the Bit-rate...................... 135 4.3.4 Speech Quality Metrics..................... 136 4.3.5 Audio Processing for Conferencing............... 137 4.4 General Concepts of Multimedia Communications............................. 138 4.4.1 Access Configurations...................... 140 4.4.2 Terminology........................... 142 4.4.3 Generalised Softswitched System Configurations....... 142 4.4.4 Generalised Multimedia Call Signalling............ 144 4.5 Signalling Plane for Packet Multimedia................. 145 4.5.1 Real-time Transport Protocol.................. 146 4.5.2 Reliable Signalling Transport in Packet Networks: SCTP.. 151 4.6 The H.323 Suite............................. 156 4.6.1 Development and Structure of H.323.............. 156 4.6.2 The H.323 Architecture..................... 157 4.6.3 Gateway Decomposition..................... 158 4.6.4 Addressing in H.323 systems.................. 160 4.6.5 H.323 Protocol Stacks...................... 160 4.7 Media Gateway Functions and Control................ 166 4.7.1 Media Gateway Entities..................... 166 4.7.2 Media Gateway Control Protocol: Megaco........... 167 4.7.3 Media Gateway Control Protocol................ 170 4.8 Multimedia Communications Based on SIP.............. 170 4.8.1 IETF Multimedia Conferencing Protocols........... 170 4.8.2 Architecture of SIP Multimedia Systems............ 172 4.8.3 SIP Methods and Modes of Operation............. 174 4.8.4 Session Description Protocol.................. 178 4.8.5 Use Cases for SIP........................ 179 4.9 Supplementary Services in Packet Telephony............. 185 4.9.1 Supplementary Services in H.323................ 185 4.9.2 Call Services in SIP Telephony................. 187 4.10 ITU-T Evolutionary Protocols: BICC................. 188 4.11 Voice on the Internet........................... 190 4.12 Conclusion................................ 191 5 Integrated Enterprise ICT Systems 193 5.1 Drivers and Requirements........................ 193 5.1.1 Convergence in the Enterprise Domain............. 194 5.1.2 Corporate Requirements..................... 195 5.1.3 Modelling Integrated Enterprise ICT Systems......... 197
viii CONTENTS 5.2 Contributions to Convergence...................... 198 5.2.1 Adoption of Commercial-off-the-Shelf Components...... 198 5.2.2 TheMultimediaSoftswitch... 199 5.2.3 Computer Telephony Integration................ 201 5.2.4 Enterprise System Software Architecture............ 214 5.3 Network Level Convergence....................... 216 5.4 Application and Service Level Convergence.............. 221 5.5 Conclusions................................ 223 6 Legacies and Lessons: Broadband ISDN, TINA and TIPHON 225 6.1 LearningfromHistory... 225 6.2 TheBroadbandISDN... 226 6.2.1 B-ISDN Architecture....................... 226 6.2.2 Asynchronous Transfer Mode.................. 227 6.2.3 Call and Connection Control.................. 229 6.2.4 Routing and Call Control Protocols.............. 230 6.2.5 B-ISDN and IN.......................... 231 6.2.6 Appraisal of B-ISDN....................... 231 6.3 TINA Architecture............................ 232 6.3.1 The TINA Architecture..................... 232 6.3.2 TINA Layers........................... 234 6.3.3 Planes: Hiding Physical Resources............... 235 6.3.4 TINAandRM-ODP... 235 6.4 Business Model and Reference Points.................. 236 6.4.1 Generic Business Domains.................... 236 6.4.2 Interdomain Reference Points.................. 238 6.4.3 Business Scenarios........................ 239 6.5 TINA Service Architecture....................... 240 6.5.1 Service Architecture: Information Viewpoint......... 241 6.5.2 Computational Viewpoint: the Service Components..... 243 6.6 Network Resource Architecture..................... 254 6.6.1 Use Case 6: Convert Steam Binding to Network Connection............................ 254 6.7 Lessons from TINA for NGNs...................... 256 6.7.1 Achievements of TINA as an NGN............... 256 6.7.2 Weaknesses of TINA....................... 257 6.8 TIPHON................................. 260 6.8.1 Objectives of TIPHON...................... 260 6.8.2 TIPHON Layered Model..................... 261 6.8.3 TIPHON Business Models.................... 261 6.8.4 TIPHON Domain and Interworking Model.......... 262 6.8.5 TIPHON Functional Architecture............... 263 6.8.6 Registration and Mobility in TIPHON............. 266 6.8.7 TIPHON Metaprotocol..................... 267 6.8.8 TIPHON Implementation using Established Protocols.... 268
CONTENTS ix 6.8.9 TIPHON and Multimedia Services............... 270 6.8.10 Appraisal of TIPHON...................... 270 6.9 Conclusion................................ 271 7 Important NGNs: Third Generation Mobile Communication Systems 273 7.1 Architectural Concepts.......................... 274 7.1.1 Concept of a Public Land Mobile Network........... 274 7.1.2 Structural Features of a PLNM................. 275 7.1.3 Geographical Relationships in a PLNM............ 277 7.2 Mobile Communication System Evolution............... 277 7.2.1 Baseline: the Second Generation Mobile Network....... 278 7.2.2 Identification of Mobile Network Generations......... 280 7.2.3 Evolution of the Radio Access Network............ 281 7.2.4 Development of the MSC.................... 282 7.2.5 Terminals in the 3G Context.................. 285 7.3 Services in the CS Domain........................ 286 7.3.1 Mobility Management in the CS Domain........... 286 7.3.2 Call Handling in 3G Systems.................. 287 7.3.3 Setting Up Bearer Connections in the 3G CS Domain.... 290 7.3.4 CAMEL-based Services in the CS Domain........... 290 7.4 Packet-switched Domain: GPRS-based Systems............ 296 7.4.1 GPRS-based Packet-domain Architecture........... 297 7.4.2 GPRS Support Node Functions................. 298 7.4.3 Mobility Management in the PS domain............ 299 7.4.4 Packet Transport in GPRS................... 300 7.4.5 Protocols Used in GPRS Access and Core........... 301 7.4.6 GPRSandCAMEL... 303 7.5 IP Multimedia Subsystem........................ 306 7.5.1 Origins and Objectives of the IMS............... 306 7.5.2 IMS Architecture and Components............... 308 7.5.3 IETFProtocolsusedinIMS... 310 7.5.4 IMSServiceModel... 312 7.5.5 Session Control.......................... 313 7.5.6 Value-added IM Services..................... 320 7.5.7 The 3GPP2 All-IP Approach to 3G Networks......... 324 7.6 Conclusion................................ 325 8 Opening the Network using Application Programming Interfaces 327 8.1 Closed Network Evolution........................ 327 8.2 Opening the Network.......................... 329 8.2.1 BusinessModels... 331 8.3 The OSA/Parlay Architecture...................... 332 8.3.1 Architectural Concepts..................... 332 8.3.2 API Definition Method and Technology Independence.... 334 8.4 FrameworkInterfacesandUseCases... 335 8.4.1 Use Case: Provisioning a Gateway Service........... 335 8.4.2 Use Cases: An Application Gains Access to a Service Manager 337
x CONTENTS 8.5 The OSA/Parlay Gateway........................ 339 8.5.1 Standard Service Capability Features............. 339 8.5.2 Interface Definition Design Pattern............... 340 8.5.3 Interaction in Communication-oriented SCFs......... 342 8.6 Communication-orientated Use Cases.................. 344 8.6.1 Call Control and User Interaction Interfaces.......... 344 8.6.2 Concept of a Call in OSA Parlay................ 344 8.6.3 Interfaces and Interactions................... 348 8.6.4 Network Event Detection and Reporting........... 348 8.6.5 Call, Call Leg and Callback Object Creation......... 350 8.6.6 User Interaction......................... 352 8.6.7 Handling a Triggered Notification................ 353 8.6.8 Call Supervision......................... 354 8.6.9 Multimedia Media Stream Control............... 356 8.6.10 Conference Control........................ 357 8.6.11 Data Session Control....................... 360 8.6.12 Generic Messaging........................ 361 8.6.13 Mobility, Account Management and Terminal Capabilities.. 363 8.6.14 Presence and Availability.................... 364 8.6.15 Charging and Account Management.............. 365 8.6.16 Connection Management.................... 365 8.6.17 OSA/Parlay Data Structures.................. 365 8.6.18 Sample Service.......................... 366 8.7 ParlayXWebServices... 368 8.7.1 The Case for a Simpler API................... 368 8.7.2 The Parlay X Web Services Architecture............ 369 8.7.3 Parlay X Web Service Example: Audiocall........... 372 8.7.4 Parlay X Implementation via OSA/Parlay........... 374 8.8 OSA/Parlay API Implementation Issues................ 374 8.8.1 Gateway-to-Network Interface................. 374 8.8.2 Abstraction Revisited...................... 377 8.8.3 Service Deployment Scenarios.................. 378 8.8.4 Service Creation......................... 379 8.9 Other Approaches to Open Networks.................. 380 8.9.1 JAIN............................... 380 8.9.2 Open Mobile Alliance Service Environment.......... 381 8.9.3 The Service Delivery Platform Concept............ 383 8.10 Conclusion................................ 384 9 Operations Support Systems 385 9.1 Relationship of OSS/BSS to ICT Systems............... 386 9.2 Evolution of OSS/BSS.......................... 388 9.2.1 The OSI Network Management Model............. 389 9.2.2 IETF Network Management Standards............. 391 9.2.3 The Telecommunications Management Network........ 395 9.3 The Telecommunications Operations Map............... 398 9.4 Enhancement of the TOM: etom................... 401
CONTENTS xi 9.5 New Generation OSS........................... 402 9.6 Conclusion................................ 405 10 Migration from Legacy to Next Generation Networks 407 10.1 Retrospect................................. 407 10.2 Reflecting on Evolution and Convergence............... 408 10.2.1 The Evolution Metaphor, with Hindsight........... 408 10.2.2 Market-oriented Objectives................... 410 10.2.3 Promoting Convergence..................... 411 10.3 Technology Migration.......................... 411 10.3.1 The Migration Process...................... 412 10.4IsThereaTargetNGN?... 415 10.4.1 Whither Fixed Networks?.................... 416 10.4.2 Are Fixed and Mobile Networks Distinct?........... 417 10.4.3 Fourth Generation Mobile Communication Systems..... 417 10.5 Managing Complexity: Avoiding Pitfalls............... 418 10.5.1 Do Not Forget the Principles.................. 419 10.5.2 Be Aware of Leaky Abstractions................ 419 10.5.3 Silos May Still be Created.................... 420 10.5.4 BeAwareofHype... 420 10.5.5 Handling The Great Debates.................. 421 10.5.6 Evolution is an Ongoing Process................ 421 10.5.7 Revisit the Treasure House................... 422 10.6 A Last Word............................... 422 Glossary 423 References 431 Index 447
Preface The present information age is enabled by telecommunications and information technology (IT) and the continued convergence of their services, technologies and business models. Within telecommunications, the historic separations between fixed networks, mobile telephone networks, data communications and enterprise networks are diminishing. The Internet initially supported the academic community but now provides communications for public information services and business IT operations. The Internet depends on telecommunications infrastructure for user access and core networks. Telecommunications increasingly adopts technology developed primarily for the Internet. Within the telecommunications world, the evolution of technology and the enhanced services that can be offered through synergies with IT have been captured in the concept of next generation networks (NGN). This concept does not mean a particular network but rather the process of evolution from present technology and services to new technologies, enabling new services and applications with both telecoms and IT characteristics. The NGN concept also captures the need for structured thinking to deal with the complexity of systems, applications and business models in information and communications technologies (ICT). This book takes as a starting point present day networks, services and operations support and maps their evolution toward specific future forms, collectively termed next generation networks. In the process, we examine the nature, process and results of convergence. Many candidate technologies are offered but few are adopted. The process of assessment, selection and integration of technology is complex, particularly when constraints exist due to the ongoing presence of legacy technology. We therefore examine the process of migration to new technologies. Many recent texts describe various next generation network technologies. The approach of this book is analytical rather than descriptive. We establish concepts, principles and architectural frameworks rather than conventional descriptions of specific technologies. Individual architectures and technologies are depicted within a framework, facilitating comparisons and drawing contrasts and assisting in integrating different technologies to form a system. The framework aids the understanding of next generation networks, their potential for supporting new, enhanced applications and their relationships with legacy networks. We draw analytical and descriptive methods from several sources, as diverse as the classical Intelligent Network, software engineering and selected telecommunications standards. Telecommunications systems must be based on standards. In most cases, standards or draft standards exist for emerging networks and services. The book analyses and explains the concepts and principles of a number of standards for networks, services and applications. The analytical approach supports assessing, designing, integrating and operating technologies in next generation networks. This understanding also informs research and development leading to new technologies.