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Voice Over IP
- By Uyless N. Black
- Published Aug 4, 1999 by Pearson.
Book
- Sorry, this book is no longer in print.
About
Features
- A discussion of the differences between voice and data networks.
- A focus on the emerging protocols and standards—Allows PSTN and IP-based networks to interoperate.
- Emphasis on signaling—e.g., the new protocol IP/ss7 that is evolving as IP networks must now support SS7, the signaling system of the public phone system.
- H.323 standard—From International Telecomm Union-ITU. Defines how delay sensitive voice traffic is to travel through local area networks.
- Testing VOIP server systems and performance.
- RSVP—Resource Reservation Protocol—Which allows users to specify Qos or service guarantees in voice (as well as video) traffic.
- Unique coverage of the new, yet to be finalized, Media Gateway Protocol—Developed largely by Bellcore and Cisco, and which will be used in the future to assure the quality of voice traffic over IP networks.
Description
- Copyright 2000
- Edition: 1st
- Book
- ISBN-10: 0-13-022463-4
- ISBN-13: 978-0-13-022463-7
2246C-4
The authoritative guide to Internet telephony
- Managing and optimizing the performance of IP voice networks
- Configuring IP-based call centers
- Internetworking IP with SS7
Uyless Black has written the essential guide for telecommunications professionals who must understand voice-over-IP (VoIP)-or deploy it. Clearheaded and free of hype, Voice Over IP carefully evaluates both VoIP's challenges and its compelling advantages, and then reviews each technical standard and critical issue associated with successful deployment.
Start by reviewing the key Internet and IP characteristics that make VoIP difficult, including packet loss and variable delay. Next, understand the role of digital signal processors (DSPs) and voice coders in VoIP. Learn how to establish paths to service providers through the local loop via ISDN, xDSL, HFC, or other approaches; review modem technology for VoIP applications; and understand today's key Internet telephony protocols. Coverage includes:
- Integrating total VoIP solutions: DSPs, voice coders, high-speed modems, gateways, local loop connectivity, and more
- The role of VoIP gateways and gatekeepers
- Internetworking SS7 with IP and H.323
- VoIP supporting protocols for multicasting (IGMP and MBONE), bandwidth reservation (RSVP, RTP, RTCP), and security services
Black describes today's best approaches for managing performance in both private and public IP networks, compares VoIP with packet voice alternatives such as Voice over Frame Relay (VoFR) and Voice over ATM (VoATM), and more. You'll also find convenient references to telephony signaling, ISDN and SS7, and V.90 modems.
Every telecommunications professional will be impacted by the VoIP revolution. Whether you're evaluating or deploying VoIP, this book places a world-class telecom consultant at your side, delivering all the objective information and insight you need to succeed.
Sample Content
Downloadable Sample Chapter
Click here for a sample chapter for this book: 0130224634.pdf
Table of Contents
1. Introduction.
Internet Telephony and Packetized Voice. Why Internet Telephony? Why Use IP for Telephony Traffic? Barriers to Successful Deployment of IP Telephony. VoIP in the Internet and in Private Internets. The Question: Not If, But How? Configuration Options. Private VoIP Networks. The Next Step. E-com and IP-based Call Centers. Configuration and Topology Choices. Basic Terms and Concepts. Attributes of the Internet. The Internet Layered Architecture. Evaluating the Factors in Packetized Voice. Accommodating to the Voice and Data Requirements in a Network. Making the Internet Look Like the Telephone Network. Summary.
2. Characteristics of the Internet & IP.
Architecture of an Internet. ISPs and the Telephone Network. Attributes of the Internet. Packet Loss. Need for Fixed Routing? Size of Packets and Kinds of Traffic IP Supports. Overview of IP. TCP and UDP. Summary.
3. Digital Signal Processors (DSPs).
Role of DSPs in Packet-Voice Operations. DSP vs. Customized Hardware. Fixed- and Floating-Point Processors. Memory Architectures. The Software is Different. Fast Fourier Transform (FFT) Operations. Signal Filters and the Finite Impulse Response (FIR) Filter. Predictability of Performance. Another Example of DSP Code. Coming Up. Summary.
4. Voice Coders.
Functions of the Voice Coder. Classification of Speech Coders. Linear Prediction Analysis-by-Synthesis (LPAS) Coders. Parameter Speech Coders: 2.4-kbit/s Mixed-Excitation LPC (MELP). Evaluating Coders. Comparison of Speech Coders. Summary.
5. Connecting to Service Providers through the Local Loop.
Path between an Internet User and the Internet. The Bandwidth Problem at the Local Loop. Terminating the Modem Analog Signal. Alternatives to the Modem-based Local Loop Access. The Integrated Services Digital Network (ISDN). Role of Digital Subscriber Line (DSL) Technologies. The Hybrid/Fiber Coax (HFC) Approach. A High-Speed Proprietary Solution. Bypassing the Circuit-Switched Technology to Reach the Internet. Summary.
6. Modems, LAPM, PPP, and the V.100 Series.
Another Look at the Layered Architecture for VoIP. Prevalent Modems. Role of DSPs in the Modem's Operations. Typical Layout. The EIA-232 Interface. Typical Layout for the Modem. Role of the Point-to-Point Protocol (PPP). The Protocol Data Unit on the Link Between the User and the ISP. V-Series Modems. The 56 kbit/s Modem (V.90). The V.110 and V.120 Recommendations for ISDN Interfaces. Summary.
7. Putting the Pieces Together.
Yet Another Look at the Layered Architecture for VoIP. Steps to the Exchange of VoIP Traffic. Another Look at the VoIP Protocol Suite. The VoIP Tunnel. Undue Processing Overhead. Summary.
8. Performance Considerations.
Packet Size, Buffer Size, Loss, and Latency. Performance of VoIP in Private Systems. Performance of VoIP in Public Systems. Summary.
9. VoIP Gateways and Gatekeepers.
The Gateway/Gatekeeper Model. The H.323 Specification. Architecture of H.323. Codec Requirements. The H.323 Protocol Stack. Registration, Admissions, and Status (RAS) Operations. Other RAS Procedures. Some Comments on H.323 and H.225.0. Summary of H.323. Media Gateway Control Protocol (MGCP). Other Protocols. Call Agents and Calls. Relationship to H.323. Endpoints, Connections, Calls, Events, Packages, and Names. The Connection Modes. MGCP Commands: For the API and the Messages. The MGCP Parameters. API Commands and Associated Parameters. MGCP Messages and Associated Parameters. Messages and Message Parameters. Examples of MGCP Operations. Summary.
10. Internetworking SS7 with IP and H.323.
Why Combine IP and SS7? Possible Configurations. The Basic Framework and the Internet Specifications. Taking Advantage of SS7 Capabilities. The SS7-IP Architectural Framework. The Reliable Signaling Gateway Protocol (RGSP). Messages and Q.931 Mappings. Interworking H.323 and SS7. Proposal for an Adaptation Layer. Summary.
11. Other VoIP Supporting Protocols.
IGMP and MBONE. RSVP. RTP. RTCP. Network Time Protocol (NTP). Security Services. DIAMETER. IPDC. DiffServ. Label-Swapping Protocols. Summary.
12. Other Packet Voice Alternatives.
Voice over Frame Relay (VoFR). Service Multiplexing. VoFR. Voice over ATM (VoATM). VoFR and VoATM: Partners with or Competitors to VoIP? Layer 3 Switching. Summary.
Appendix A: Telephony Signaling.
Appendix B: ISDN and SS7.
Appendix C: Tutorial on the V.34 and V.90 Modems.
Index.
Preface
Preface
This book is one in a series of books called, "Emerging Communications Technologies." As the name of the book implies, the focus is on the Internet and private internets in relation to the support of voice traffic. The book is an expansion of Advanced Features of the Internet, also part of this series. The subject matter of this book is vast and my approach is to provide an introduction to the topic. But in consonance with the intent of this series, this survey also has considerable detail but not to the level of detail needed to design a system. For that, I leave you to your project team and the various specifications that establish the standards for Internet telephony.
This book is an intermediate-to-advanced level text. As such, it assumes the reader has a background in voice and data communications and the Internet protocol suite. Notwithstanding, for the new reader, I have provided several tutorials, and I guide you to them in the appropriate parts of the book. I guide the more experienced reader away from them.
I hope you find this book a valuable addition to your library.
Notes to the ReaderIn writing multiple books about data and voice communications systems, the author is faced with a question: How much overlap (redundancy of material) should there be among the books in the series? If the overlap is too little, the reader must buy other books in the series to fill the gaps. If the overlap is too great, the reader who has purchased other books in the series may feel cheated by spending additional money to obtain the same information.
My approach is to try to strike a compromise between the two extremes. If another book in the series contains information on a topic that is relevant to the topic of the current book, yet is not an impelling subject to know in order to read the current book, I make reference to the book. However, that is not always possible. In a few cases, it is necessary to include material from other books in the series. Otherwise, the book in question becomes a fragmented reference to other books. I have taken this approach with this book. I trust you find this an efficient and useful way to deal with this matter.
To help strike this compromise, I have included four appendices that are extracted from some of my other books. A basic knowledge of telephony signaling, the V.34 modem, ISDN, and SS7 will be very helpful as you read some of these chapters about voice over IP, and I have included tutorials on these subjects in the Appendices at the back of this book. I also have a tutorial on the V.34 and V.90 modems.
Explanations of messages and protocol flowsThis book is a survey (albeit a detailed one) of the emerging VoIP technology. A wide variety of VoIP control messages and protocols are used to support VoIP, and the standards bodies and the Internet tasks forces are defining hundreds of messages and scores of protocol flows between VoIP gateways, call agents, and user machines. It is not the intent of this book to explain the contents of each message and each protocol flow, which would simply duplicate the VoIP specifications. Instead, I provide tutorial explanations of these messages and flows, as well as selected examples of each. In each case, I provide you references to the original specifications. In this manner, the book should provide you with a handy tutorial and reference tool, as well as a pointer toward more information if you so desire.
Internet Drafts: Work in ProgressA considerable portion this book is devoted to explaining many Internet-based specifications pertaining to packet telephony. I had planned on waiting a year or so before writing about these specifications, but requests from my clients and publishers dictated otherwise. Indeed, some vendors are already writing code based on the specifications, even though they are not yet finished. Keep in mind that the Internet Drafts are works in progress, and should be viewed as such. You should use the drafts with the expectation that they may change. Notwithstanding, if used as general tutorials, the Drafts discussed in this book are "final enough" to warrant their explanations.
For all the Internet standards and draft standards the following applies: Copyright © The Internet Society (1998). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English.
The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns.
Thanks toI would like to thank four organizations for their contributions to this book. First, Mier Communications provided two studies on VoIP products, and this information can be found in Chapter 8. I thank Mier for their excellent work. Second, Nortel provided me with valuable information on Nortel's One Meg Modem, as well as some of their emerging IP connect technologies, found in several chapters. Third, British Telecom (BT) has been a great help in their contributions on codecs. Fourth, the various Internet Task Forces have provided much of the information on the emerging VoIP protocols.