Voice and Video Conferencing Fundamentals (Networking Technology Series)
Voice and Video Conferencing Fundamentals\ Design, develop, select, deploy, and support advanced IP-based audio and video conferencing systems\ Scott Firestone, Thiya Ramalingam, Steve Fry\ As audio and video conferencing move rapidly into the mainstream, customers and end users are demanding unprecedented performance, reliability, scalability, and security. In Voice and Video Conferencing Fundamentals, three leading experts systematically introduce the principles, technologies, and protocols...
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Voice and Video Conferencing FundamentalsDesign, develop, select, deploy, and support advanced IP-based audio and video conferencing systemsScott Firestone, Thiya Ramalingam, Steve FryAs audio and video conferencing move rapidly into the mainstream, customers and end users are demanding unprecedented performance, reliability, scalability, and security. In Voice and Video Conferencing Fundamentals, three leading experts systematically introduce the principles, technologies, and protocols underlying today’s state-of-the-art conferencing systems. Discover how to use these concepts and techniques to deliver unified, presence-enabled services that integrate voice, video, telephony, networks, and the Internet—and enable breakthrough business collaboration.The authors begin with a clear, concise overview of current voice and video conferencing, including system components, operational modes, endpoints, features, and user interactivity. Next, they illuminate conferencing architectures, offering practical insights for designing today’s complex IP-based conferencing and collaboration systems.Topics covered in this book include video codecs, media control, SIP and H.323 protocols and applications, lip synchronization in video conferencing, security, and much more. Throughout the book, the authors draw on their extensive experience as Cisco® technical leaders, showing how to avoid the most common pitfalls that arise in planning, deployment, and administration.Voice and Video Conferencing Fundamentals is for every professional involved with audio or video conferencing: network and system administrators, engineers, technology managers, and Cisco solution partners alike. Whether you’re involved with design, development, selection, implementation, management, or support, you’ll find the in-depth knowledge you need to succeed.Scott Firestone holds a master’s degree in computer science from MIT and has designed video conferencing and voice products since 1992, resulting in five patents. Thiya Ramalingam is an engineering manager for the Cisco Unified Communications organization. Thiya holds a master’s degree in computer engineering and an MBA degree from San Jose State University. Steve Fry, a technical leader in the Cisco Unified Communication organization, has spent the last several years designing and developing telephony and conferencing products. Thoroughly understand the fundamentals of audio and video conferencing over IP networks Architect networks for optimal performance and reliability in conferencing applications Leverage new advances in video architecture, from emerging codecs to distributed implementations Understand how SIP and H.323 compare, and when to use each Optimize synchronization between audio and video Secure conferencing traffic without compromising performance or connectivity Learn how to evaluate vendors and make better buying decisionsForewordIntroductionChapter 1 Overview of Conferencing ServicesChapter 2 Conferencing System Design and ArchitectureChapter 3 Fundamentals of Video CompressionChapter 4 Media Control and TransportChapter 5 Signaling Protocols: Conferencing Using SIPChapter 6 Signaling Protocols: Conferencing Using H.Chapter 7 Lip Synchronization in Video ConferencingChapter 8 Security Design in ConferencingAppendix A Video Codec StandardsThis book is part of the Cisco Press® Fundamentals Series. Books in this series introduce networking professionals to new networking technologies, covering network topologies, sample deployment concepts, protocols, and management techniques.Category: Cisco Press/NetworkingCovers: Voice and video conferencing1587052687
Foreword xviiiIntroduction xixChapter 1 Overview of Conferencing Services 3Conference Types 3Ad Hoc Conferences 4Reservationless Conferences 5Scheduled Conferences 6Voice and Video Conferencing Components 9Video Conferencing Modes 11Voice-Activated Conferences 11Continuous Presence Conferences 13Lecture Mode and Round-Robin Conferences 15Types of Endpoints 16Desktop Conferencing Systems 16Room Conferencing Systems 16Telepresence Systems 16Video Controls: Far-End Camera Control 17Text Overlay 18Summary 18Chapter 2 Conferencing System Design and Architecture 21Components of a Conferencing System 21User Interface 23Conference Control 25Control Plane 26Media Plane 27Conferencing Architectures 37Centralized Architecture 37Distributed Architecture 38Full-Mesh Networks 40Advanced Conferencing Scenarios 41Escalation of Point-to-Point-to-Multipoint Call 41Lecture Mode Conferences 41Panel Mode Conference 42Floor Control 42Video Mixing and Switching Scenarios 42Summary 43References 43Chapter 3 Fundamentals of Video Compression 45Evaluating Video Quality, Bit Rate, and Signal-to-Noise Ratio 45Video Source Formats 47Profiles and Levels 47Frame Rates, Form Factors, and Layouts 47Standard and High Definitions 48Color Formats 49Basics of Video Coding 52Preprocessing 52Post-Processing 54Encoder Overview 55Hybrid Coding 72Hybrid Decoder 72P-Frames 74Hybrid Encoder 74Predictor Loop 76Motion Estimation 77B-Frames 82Predictor Loops for Parameters 86Error Resiliency 88Scalable Layered Codecs 91SNR and Spatial Scalability 93Temporal Scalability 95Switching Frames 99Video Codecs 100Video Stream Hierarchy 100Macroblocks 101HD-Capable Codecs 102Summary 102References 103Chapter 4 Media Control and Transport 105Overview of RTP 105RTP Header 107RTP Port Numbers 111SSRC Collisions 111RTP Header Extensions 112Overview of RTCP 113RTCP Packet Headers 113RTCP Sender Report 114RTCP Receiver Report 116RTCP Source Description (SDES) 117RTCP BYE 119RTCP APP 120RTP Devices in Conference Systems 120RTP Translator 120RTP Mixer 123Audio Mixer 123Video MCU 124Video Switcher 124Video Stream RTP Formats 126H.263 126H.264 133Detecting Stream Loss 141Summary 142References 143Chapter 5 Signaling Protocols: Conferencing Using SIP 145SIP Overview 145User Agent 146Proxy Server 146Redirect Server 147Registrar 147SIP Transactions and Dialogs 148SIP Messages 149SIP Requests 149SIP Responses 152SIP Record Routing 153Event Subscription and Notification 154Session Description Protocol 155SIP Conferencing Models 157Conference URI 157Early and Delayed Offer 158DTMF Support 159Ad Hoc Audio Conferencing 160Ad Hoc Video Conferencing 162Video SDP Extensions 163Bandwidth Information in the SDP 167Multiple Stream Support and Grouping of Media Lines 168 Escalation and De-escalation 169Media Control Support 172Scheduled Conferences 173Entry IVR 174In-Conference Features 177Roll Call 177Hold and Resume 178Mute and Unmute 179Outdial 179RSVP/QoS Support in Conferencing Flows 180Summary 182References 183Chapter 6 Signaling Protocols: Conferencing Using H.323 185H.323 Overview 185H.323 Endpoint Aliasing 187H.225 Call Signaling 188H.225 Message Format 188Common H.225 Message Types Used in H.323 Signaling 189H.245 Control Protocol 191H.245 Messages 192Video-Specific H.245 Messages 202H.323 Fast Connect Mode 204Using the Empty Capability Set 207Call Hold Signaling with the Empty Capability Set 207Call Transfer with the Empty Capability Set 207H.323 Device Types 208H.323 Gatekeeper Services 209Required H.323 Gatekeeper Features 209Optional H.323 Gatekeeper Features 210Gatekeeper Signaling Options 211Gatekeeper RAS Signaling 212Mid-Call Bandwidth Requests 214Configuring a Gatekeeper in Cisco Unified CallManager 215Configuring Gatekeeper Support in a Cisco IOS Router 217H.225 Call Setup for Video Devices Using a Gatekeeper 217Using Service Prefixes with MCUs 219Summary 220References 220Chapter 7 Lip Synchronization in Video Conferencing 223Understanding Lip Sync Skew 223Human Perceptions 223Measuring Skew 225Delay Accumulation 226Delays in the Network Path 228Lip Sync Approaches 229Poor Man’s Lip Sync 230Common Reference Lip Sync 232Understanding the Sender Side 232Sender Audio Path 233Video Source Format 235Sender Video Path 238Understanding the Receive Side 241Audio Receiver Path 241Receiver Video Path 243Types of Playout Devices 244RTP 244Canonical RTP Model 244RTP Time Stamps 246Using RTP for Buffer-Level Management 247Correlating Timebases Using RTCP 250NTP 250Forming RTCP Packets 251Using RTCP for Media Synchronization 252Lip Sync Policy 254Summary 255References 255Chapter 8 Security Design in Conferencing 257Security Fundamentals 257Threats 258Confidentiality Attacks 258Denial-of-Service Attacks 259Authentication and Identity Attacks 262Network Infrastructure Attacks 263 Endpoint Infrastructure Attacks 266Server Attacks 267Configuring Basic Security 269Port Usage 270H.323 Port Usage 270SIP Port Usage 275SCCP Port Usage 275Preset Port Numbers 276NAT and PAT 276NAT Classifications 277NAT Complications for VoIP Protocols 284NAT ALGs 285NAT/FW Traversal Solutions 285Encryption Basics 299Symmetric Encryption 299Secure Hashes 299Asymmetric Encryption: Public Key Cryptography 300Nonrepudiation 309Key Distribution 309IPsec and TLS for Secure Signaling 310IPsec 311TLS 311Media Encryption 312security-descriptions 312MIKEY 313H.323 Encryption: H.235 313H.235.1 314H.235.2 316H.235.3 319H.235.6 319SIP Encryption 321SIP-Digest 321SCCP Encryption 324Summary 324References 325Appendix A Video Codec Standards 327021907TOC1587052687
