- Copyright
- Preface
- 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
- Characteristics of the Internet and IP
- 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
- Voice Coders
- 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
- 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
- V.24
- 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
- V.120
- SUMMARY
- Putting the Pieces Together
- Performance Considerations
- 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
- T.120
- H.245
- H.324
- 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
- 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 (RSGP)
- MESSAGES AND Q.931 MAPPINGS
- INTERWORKING H.323 AND SS7
- PROPOSAL FOR AN ADAPTATION LAYER
- SUMMARY
- Other VoIP Supporting Protocols
- Other Packet Voice Alternatives
- Telephony Signaling
- ISDN and SS7
- Tutorial on the V.34 and V.90 Modems
- Abbreviations
- References
Chapter 8. Performance Considerations
This chapter examines several issues pertaining to the performance of VoIP networks. The first part of the chapter examines the trade-offs of packet size, buffer size, packet loss and packet latency. The next part of the chapter provides a summary of three studies conducted on VoIP performance in private internets, and in the public Internet.
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