Practical VoIP Using VOCAL - pudn.com-paper

1、Table of ContentsPreface 1. VOCAL: Say, What? Whats This All About? System Architecture Wheres This Going? Whats in This for You? 2. Setting Up a Phone System at Home Hardware Requirements Software Requirements Acquiring VOCAL Software Installing and Deploying VOCAL Testing Your Installation Accessi

2、ng Provisioning Installing and Running a UA from Separate Hosts Configuring Software UAs Starting, Restarting, and Stopping VOCAL 3. Setting Up an Internal Trial System Interfacing with the PSTN Setting Up a Redundant System Configuring a PSTN Gateway Installing VOCAL onto a Multihost System Working

3、 with VOCAL 4. Provisioning Users Quick Step for Provisioning Users Logging into the Provisioning System User Configuration Screen Adding, Viewing, Editing, and Deleting Users 5. Configuring System Parameters and Dial Plans Login Procedure Configuring Servers The System Folder 6. Provisioning Server

4、s The Servers Folder Call Detail Record Servers Redirect Server User Agent Marshal Server Gateway Marshal Servers Conference Bridge Marshal Server Internetwork Marshal Server Feature Servers Voice Mail Feature Servers JTAPI Servers Heartbeat Server Policy Servers 7. Session Initiation Protocol and R

5、elated Protocols What Is SIP? Sample Message Flows Message Headers SDP Messages Sample SIP Call Message Flow Forking Weird Situations 8. Vovida SIP Stack Architecture Constructing and Deconstructing Messages Parsing Transporting Compiling and Running the Stack Bugs/Limitations 9. Base Code State Mac

6、hine Class Structure High-Level Flow Key Data Structures Dependencies 10. VOCAL User Agent Call Processing Multicall Processing Looking Through the Code Other UA Processes B2BUA 11. SIP Proxy: Marshal Server High-Level Design Functionality Security Authentication 12. Redirect Server High-Level Desig

7、n Routing Ongoing Development 13. CPL Feature Server What Are Features? Core Features Set Features New Features SIP Messages and Feature Servers Scriptable Feature Development How CPL Script Converts to a C+ State Machine Feature Activation How to Develop a Feature Feature Server Files Writing Your

8、Next Killer Feature 14. Unified Voice Mail Server High-Level Design Voice Mail Feature Server Voice Mail User Agent Voice Mail Server Setting Up a Voice Mail System 15. MGCP Translator Media Gateway Control Protocol MGCP Translator Test Tools Future Development Detailed Message Flows State Diagram 1

9、6. H.323 Translator H.323 Background Registration and Admission Source Code Getting Started 17. System Monitoring SNMP Support MIBs SNMP Daemon Network Manager Agent API SNMP GUI Adding MIBs Creating New Agent Code Heartbeat Server 18. Quality of Service and Billing Quality of Service Billing OSP Bi

10、lling and Toll Fraud 19. Provisioning Old Provisioning System Mascarpone Provisioning System Provisioning Server Provisioning Interface Libraries Java User Interface GUI Screens DTD for Data Definition Examples of Protocol Transmissions/Replies A. VOCAL SIP UA Configuration FileB. Testing ToolsIndex

11、 Practical VoIP Using VOCALby Luan Dang, Cullen Jennings, and David KellyCopyright 2002 OReilly Media, Inc. All rights reserved.Printed in the United States of America.Published by OReilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472.OReilly Media, Inc. books may be purchased fo

12、r educational, business, or sales promotional use. Online editions are also available for most titles (). For more information, contact our corporate/institutional sales department: (800) 998-9938 or corporate.Editor:Jim SumserProduction Editor:Jane EllinCover Designer:Ellie VolckhausenInterior Desi

13、gner:David FutatoPrinting HistoryJuly 2002:First Edition.Nutshell Handbook, the Nutshell Handbook logo, and the OReilly logo are registered trademarks of OReilly Media, Inc. Practical VoIP Using VOCAL, the image of a snipefish, and related trade dress are trademarks of OReilly Media, Inc. Many of th

14、e designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and OReilly Media, Inc. was aware of a trademark claim, the designations have been printed in caps or initial caps. Cisco and all Cisco-based tradem

15、arks are registered trademarks of Cisco Systems, Inc.While every precaution has been taken in the preparation of this book, the publisher and authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein.Library of Congress Catalo

16、ging-in-Publication DataDang, LuanPractical VoIP Using VOCAL/Luan Dang, Cullen Jennings, & David Kelly.p. cm.Includes index.ISBN 0-596-00078-21. Internet telephony I. Jennings, Cullen II. Kelly, David III. Title.TK5105.8865 .D35 2002621.38212dc21 202002023323C 8/05PrefaceThis book is the product of

17、a Silicon Valley success story called Vovida Networks, a high-technology start-up founded by Alan Knitowski and Luan Dang. Vovida recruited an international team of talented developers to build an open source () phone system that became known as the Vovida Open Communication

18、Application Library (VOCAL). Vovidas aim was to enable a community of developers to produce new Voice over IP (VoIP) applications that would challenge the established companies, dispel popular beliefs about phone systems, and contribute to a new world of interactivity and interoperability. All of th

19、e technololgy that Vovida built is open source. You can build a complete phone system from it, and this book describes how to acquire, compile, install, and work with the applications as an end user, and how to work with the code as a developer.During the time that Vovida was building its team and d

20、eveloping its applications, the industry was going through an exciting period of growth and innovation. The Telecommunications Act of 1996 (/telecom.html) had opened up a previously closed industry to .promote competition and reduce regulation in order to secure lower prices and hig

21、her quality services for American telecommunications consumers and encourage the rapid deployment of new telecommunications technologies. At the same time, many venture capital firms had relaxed their guidelines about lending and initial public offerings (IPOs). This mixture of new law and new money

22、 helped establish more than 1000 new telecom service providers, along with many new software and hardware manufacturers. A strong stock market also permitted established organizations to expand their capabilities by acquiring innovative start-ups.At the height of this prosperity, Vovida Networks was

23、 acquired by Cisco Systems, which enabled VOCAL and a new web site called V () to continue growing and expanding their communities. VOCAL is currently being developed not only at Cisco, but also inside the laboratories, cubicles, and basements of community members scatte

24、red throughout the world. V is a communications community site dedicated to providing a forum for open source software used in datacom and telecom environments. From April 2001 to January 2002, the number of downloads of VOCAL source code* grew from 697 to 1293 per month, almost a 100% incr

25、ease in 10 months, demonstrating the steady momentum of the open source movement in Voice over IP.* There is no correlation between number of downloads and active VOCAL systems. Any given person could download one copy of VOCAL over another or could run multiple systems from a single download. Howev

26、er, the growth in the monthly number of downloads is a strong indication of the growth of the community.Whether it is through the mailing lists, from meeting developers at different trade shows, or from talking directly to people who have worked with VOCAL in their corporate labs, we hear a consiste

27、nt story coming from the community: those who have built their projects on top of VOCAL components, rather than from scratch, have significantly reduced their development costs and time to market.We want you to share in our success by creating the next killer application, hosting a friends and famil

28、y phone system at home, or finding another creative outlet that satisfies your curiosity about VoIP. We look forward to receiving your messages on our mailing lists as we hope to find out more about your experiences with running VOCAL.How to Use This BookThis book has been written to appeal to three

29、 types of VOCAL users:HobbyistOne who is interested in using VOCAL as a small phone system, who may make some minor code changes but has no interest in turning it into a commercially viable productSystem administratorOne who has been tasked to maintain a VOCAL-based phone system but who has no inter

30、est in VoIP software developmentProfessional developerOne who is using VOCAL to test commercial applications or who is building new commercial applications on top of the VOCAL source codeHere are some suggestions about how each type of user can get the most out of this book:HobbyistUse the instructi

31、ons in Chapter 2 to install VOCAL onto a single host and to test your installation, and then refer to Chapters 4, 5, and 6 for information about working with users, dial plans, and servers. Refer to Chapter 8 to learn about the SIP stack architecture and Chapter 9 to learn about the base code. After

32、ward, refer to the chapters from the second half of the book for more information about the other VOCAL modules.System administratorRefer to Chapters 2 and 3 for information about installing VOCAL and configuring IP phones and gateways, and then refer to Chapters 4, 5, and 6 for information about pr

33、ovisioning users, dial plans, and servers.DeveloperRefer to Chapter 2 about installing VOCAL; refer to Chapters 4, 5, and 6 about provisioning users, dial plans, and servers; and then refer to the chapters in the rest of the book that best suit your needs.How This Book Is OrganizedWe have organized

34、the book so that you can get started and make something happen on your home or test PC quickly and easily. Were hoping that your excitement from making calls on your own phone system will inspire you to look further into the systems complexity.In order to make our delivery of this material as straig

35、htforward as possible, we have refrained from discussing the technical details of the signaling methods and architectural models throughout the first six chapters. If you want the theory first and the practical second, turn to Chapter 7 and read through the rest of the book before returning to Chapt

36、er 2. We think that most readers will prefer getting their hands dirty first.Chapter 1, VOCAL: Say, What?Gives you a brief overview of what this book, the software, and Voice over IP are all about.Chapter 2, Setting Up a Phone System at HomeProvides instructions about getting a phone system working

37、at home on a single Linux host and then adding new phone devices to your system.Chapter 3, Setting Up an Internal Trial SystemProvides instructions about setting up an internal system that can support dozens of users working in a professional environment. This chapter also includes configuration ins

38、tructions for gateways and how to deploy the system onto a distributed network of hosts.Chapter 4, Provisioning UsersProvides information about adding users to the system and the different options available for features and other end-user parameters.Chapter 5, Configuring System Parameters and Dial

39、PlansProvides information about setting up global system values such as dial plans and the multicast address used for heartbeats.Chapter 6, Provisioning ServersProvides information about setting up individual server types, configuring their IP addresses, and adding new servers to the system.Chapter

40、7, Session Initiation Protocol and Related ProtocolsA general overview of SIP, SDP, and the different message types used by these protocols. Includes some illustrated call flows and a line-by-line analysis of the basic message content.Chapter 8, Vovida SIP StackA specific overview of Vovidas impleme

41、ntation of a SIP stack including class diagrams, discussions about data structures, some insight into how the stack was developed, and what the engineers were working on as this book was being written.Chapter 9, Base CodeA short but important chapter about the base code that is common to most of the

42、 VOCAL servers.Chapter 10, VOCAL User AgentDiscusses the SIP user agent (UA) that comes with VOCAL. This UA is useful for testing and demonstrating how the software works, but it was never intended as a practical softphone for end users. This chapter discusses the data structures and some basic call

43、 flows.Chapter 11, SIP Proxy: Marshal ServerThe Marshal server is our name for a SIP-edge proxy server that provides authentication and security for VOCAL. This chapter looks at the data structures that make the Marshal server work and includes additional, general information about authentication, s

44、ecurity, and working with firewalls.Chapter 12, Redirect ServerThe VOCAL Redirect server performs the duties described in the standard (RFC 2543) and also provides registration and location services. This chapter looks at the data structures and provides additional information about routing, ENUM, a

45、nd Telephony Routing over IP (TRIP).Chapter 13, CPL Feature ServerThe Call Processing Language (CPL) Feature server is an implementation of the SIP proxy that provides basic features such as call forwarding. This chapter provides information about CPL and the data structures that make up the server.

46、Chapter 14, Unified Voice Mail ServerAs a trade show demo, we wrote a voice mail server. Despite its basic functionality, it works for a small user population and has become a popular module within the user community. This chapter explains the data structures and a few of the solutions that we imple

47、mented to make this service work.Chapter 15, MGCP TranslatorThe MGCP translator allows VOCAL to talk to MGCP gateways, which are normally attached to analog phone sets. This chapter discusses the MGCP protocol stack, the translator, and call flows through the state machine.Chapter 16, H.323 Translat

48、orThe H.323 translator allows H.323 endpoints such as NetMeeting or H.323 gateways to be used with VOCAL. This chapter provides a simplified look at the data structures with some basic call flows.Chapter 17, System MonitoringWe took the UC Davis SNMP stack and adopted it into VOCAL to provide networ

49、k monitoring. This chapter discusses how this was accomplished and how you can add a new Management Information Base (MIB) to your system.Chapter 18, Quality of Service and BillingAdvanced topics. Quality of Service (QoS) and using the Open Settlement Protocol (OSP) are still in a state of developme

50、nt. This chapter also discusses how we built a Remote Authentication Dial-In User Service (RADIUS) stack to talk to billing servers.Chapter 19, ProvisioningProvides an analysis of the code behind the provisioning system that is shown in Chapters 4, 5, and 6. It then discusses the new provisioning sy

51、stem that we plan to merge with VOCAL.Appendix A, VOCAL SIP UA Configuration FileAn annotated configuration file that explains all the available settings for the VOCAL SIP UA.Appendix B, Testing ToolsConventions Used in This BookThe following formatting conventions are used throughout this book: Ita

52、lic is used for commands, filenames, directories, functions, threads, and operators. Constant width is used for IP addresses, branches in a SIP message flow, and equations. Constant width italic is used for replaceable text. Constant width bold is used for user input.This icon designates a note, whi

53、ch is an important aside to the nearby text.This icon designates a warning relating to the nearby text.How to Contact UsPlease address comments and questions concerning this book to the publisher:OReilly & Associates, Inc. 1005 Gravenstein Highway North Sebastopol, CA 95472 (800) 998-9938 (in the Un

54、ited States or Canada) (707) 829-0515 (international or local) (707) 829-0104 (fax)There is a web page for this book, which lists errata, examples, or any additional information. You can access this page at:To comment or ask technical questions about this book, send email to:bookquestionsFor more information about OReillys books, conferences, Resource Centers, and the OReilly Network, see the OReilly web site at:AcknowledgmentsFirst of all, we would like to thank the members of the VOCAL development team who helped us bring this book to you