COPYRIGHTED MATERIAL. Contents. Foreword. Acknowledgments

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1 Contents Foreword Preface Acknowledgments 1 Introduction Motivation for Network Convergence The Core Network Legacy Service Requirements New Service Requirements Architectures Moving to SIP Growing Revenue Network Operators Dealing with Convergence Scenario 1 A Cable Operator Scenario 2 A Video-on-demand Service Provider Scenario 3 A High-speed Internet Service Provider Scenario 4 A Mobile Operator Scenario 5 A Fixed Network Operator Scenario 6 The PSTN Operator Enabling Technologies for Converged Networks 14 2 Call Control in the NGN NGN Network Architectures The Operation of Call Control Call Processing in the Legacy PSTN Call Processing in an NGN Call Agent The Basic Call State Model The IN CS-2 Originating BCSM The IN CS-2 Terminating BCSM Call Signalling in the NGN and the Role of SIP A Brief Discussion of the SIP Architecture and Network Elements A Simple Call Set-up Using SIP Signalling Simple Call Clearing Using SIP Signalling SIP Redirection Servers and SIP Forking Privacy CLI and the SIP P-Asserted-Identity Header SIP Registration Procedures Routing SIP Messages, Record-route, Route and Via Headers 60 COPYRIGHTED MATERIAL xi xiii xv

2 vi Contents SIP Routing in Real Networks The P-Charging-Vector Header The SDP Protocol An Example Session Description The v =, o=, s= and t = Lines The m = Line (Media Announcement) Static and Dynamic RTP/AVP Payload Types SDP Attribute Lines Building an SDP Answer to and SDP Signalling Conventions in SIP Media Transport Using RTP and RTCP The RTP Header The RTCP Protocol RTCP Reports RTCP Extended Reports RTP Port Numbers and Symmetric RTP Addressing Issues The SIP tel-uri Locating Telephone Numbers, ENUM Summary 77 References 78 3 Securing the Network and the Role of Session Border Gateways General Principles of Security and the NGN Security Assets Risk Analysis Common Pitfalls The Problem of Secrets Passwords Shared Secrets Public Key Infrastructure (PKI) IPsec Key Management Key Distribution Session Border Controllers and Session Border Gateways Functions of a Session Border Controller Session Border Gateways Gates and Pinholes Preventing Denial of Service Attacks with Session Border Gateways Additional Functions of Session Border Gateways and Session Border Controllers Protecting the PSTN Call Control Platforms in the NGN The Importance of Customer Access Type on Security SIP Security Mechanisms The Impact of the Threat Model on Control Plane Security Summary 97 References 98

3 Contents vii 4 The NGN and the PSTN Circuits and What they Carry Signalling and Supervision Signalling and Supervision on the Access Link Inter-exchange Signalling and Supervision The Birth of the Call Agent History of an Idea Applying the Architecture Media Gateways A Look at Media Gateway Control Protocols SGCP and MGCP The Megaco/H.248 Protocol The Sigtran Protocols The Stream Control Transmission Protocol (SCTP) User Protocol Adaptive Layers Summary 146 References Evolution of Mobile Networks and Wireless LANs Introduction G and 2G Mobile Networks Development of 3G Release 99 UMTS Architecture General Packet Radio Service (GPRS) Enhanced Data Rates for GSM Evolution (EDGE) Release 4 UMTS Architecture Circuit Switched Domain Packet Switched Domain Wideband Code Division Multiple Access (W-CDMA) Introduction to IMS The Proxy Call Session Control Function (P-CSCF) The Interrogating Call Session Control Function (I-CSCF) The Serving Call Session Control Function (S-CSCF) IMS Subscriber Identities The Breakout Gateway Control Function (BGCF) The Media Resource Function (MRF) GPRS Access to IMS Creating a Session Authorisation and Reservation of an IP bearer Storage of Session Paths Broadband Data Wireless Access Wireless LAN Interworking GPP Release 6 Integration of Wireless LANs Mobile TV and Video Related Work in other Standards Bodies ETSI 179

4 viii Contents ITU-T ATIS IETF 182 Summary 184 Appendix 185 3GPP Specifications 185 3GPP Technical Specifications for MBMS 186 MBMS Bearer Service (Distribution Layer) 186 MBMS User Service (Service Layer): 187 IETF Specifications 187 References Value-added Services Introduction Service Creation and Delivery Technologies Service Delivery in the PSTN SIP Application Servers Parlay Parlay X Service Orchestration IMS Model MSF Model Service Orchestration Examples Service Combination Example IMS Conflict Resolution Example MSF Service Delivery Platforms 226 Summary 228 References Core Network Architecture The Convergence Layer: Multiprotocol Label Switching Quality of Service in IP Networks MPLS Traffic Engineering and Traffic Management Signalling and Routing in MPLS Networks Protection, Restoration and Service Assurance in MPLS Virtual Private Networks Layer 3 Virtual Private Networks Layer 2 Virtual Private Networks Summary 263 References Guaranteeing Quality of Service in the NGN Introduction Defining QoS QoS in IP Networks Traffic Engineering in the MPLS Core 273

5 Contents ix 8.5 Video Services Business VPN Services Extending QoS for VPN Services across Multiple Providers QoS and the PSTN QoS Architectures for PSTN Services A Simple DiffServ-based QoS Solution A Session Border Controller based Solution with Explicit Reservations Bandwidth Manager based Architectures The MSF Architecture for Bandwidth Management The Bandwidth Management Layer and Scaling the Network Interactions with the Underlying Network Handling Network Interconnect An Alternative Approach to Network Interconnect Signalling QoS Requirements Signalling QoS with SIP Preconditions Bandwidth Reservation Using the Diameter Protocol Challenging Cases and Responding to Network Failures A Call Set-up with Guaranteed QoS Using Bandwidth Managers End-to-end QoS, Spanning Multiple Networks Supporting IMS-based Networks Protecting the Network from Application Layer Overload Principles of Control Plane Overload Control Plane Overload Control in the PSTN An Overview of Control Plane Overload Control in the NGN Congestion Control Mechanisms Required for Black Phones and Access Gateways Trunking Gateway Overload Protection Mechanisms A Framework for SIP Overload Control A Protocol-independent Approach (GOCAP) Summary 328 References 330 Index 333

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