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Voice over IP Fundamentals, Second Edition

Book Description

A systematic approach to understanding the basics of voice over IP

  • Understand the basics of enterprise and public telephony networking, IP networking, and how voice is transported over IP networks

  • Learn the various caveats of converging voice and data networks

  • Examine the basic VoIP signaling protocols (H.323, MGCP/H.248, SIP) and primary legacy voice signaling protocols (ISDN, C7/SS7)

  • Explore how VoIP can run the same applications as the existing telephony system but in a more cost-efficient and scalable manner

  • Delve into such VoIP topics as jitter, latency, packet loss, codecs, QoS tools, and security

Voice over IP (VoIP) has become an important factor in network communications, promising lower operational costs, greater flexibility, and a variety of enhanced applications. To help you understand VoIP networks, Voice over IP Fundamentals provides a thorough introduction to the basics of VoIP.

Voice over IP Fundamentals explains how a basic IP telephony infrastructure is built and works today, major concepts concerning voice and data networking, and transmission of voice over data networks. You’ll learn how voice is signaled through legacy telephone networks, how IP signaling protocols are used to interoperate with current telephony systems, and how to ensure good voice quality using quality of service (QoS).

Even though Voice over IP Fundamentals is written for anyone seeking to understand how to use IP to transport voice, its target audience comprises both voice and data networking professionals. In the past, professionals working in voice and data networking did not have to understand each other’s roles. However, in this world of time-division multiplexing (TDM) and IP convergence, it is important to understand how these technologies work together. Voice over IP Fundamentals explains all the details so that voice experts can understand data networking and data experts can understand voice networking.

The second edition of this best-selling book includes new chapters on the importance of billing and mediation in a VoIP network, security, and the common types of threats inherent when packet voice environments, public switched telephone networks (PSTN), and VoIP interoperate. It also explains enterprise and service-provider applications and services. 

Table of Contents

  1. Copyright
  2. About the Authors
  3. About the Technical Reviewers
  4. Acknowledgments
  5. Icons Used in This Book
    1. Command Syntax Conventions
  6. Introduction
    1. Purpose of This Book
    2. Who Should Read This Book?
    3. Chapter Organization
    4. Features and Text Conventions
    5. Timeliness
    6. The Road Ahead...
  7. I. PSTN
    1. 1. Overview of the PSTN and Comparisons to Voice over IP
      1. The Beginning of the PSTN
      2. Understanding PSTN Basics
        1. Analog and Digital Signaling
        2. Digital Voice Signals
        3. Local Loops, Trunks, and Interswitch Communication
        4. PSTN Signaling
          1. User-to-Network Signaling
          2. Network-to-Network Signaling
      3. PSTN Services and Applications
        1. PSTN Numbering Plans
          1. NANP
          2. ITU-T International Numbering Plan
      4. Drivers Behind the Convergence Between Voice and Data Networking
        1. Drawbacks to the PSTN
      5. Packet Telephony Network Drivers
        1. Standards-Based Packet Infrastructure Layer
        2. Open Call-Control Layer
        3. VoIP Call-Control Protocols
          1. H.323
          2. MGCP (Evolution from SGCP and IPDC)
          3. SIP
          4. H.248/MEGACO
        4. Open Service Application Layer
      6. New PSTN Network Infrastructure Model
      7. Summary
    2. 2. Enterprise Telephony Today
      1. Similarities Between PSTN and ET
      2. Differences Between PSTN and ET
        1. Signaling Treatment
        2. Advanced Features
      3. Common ET and PSTN Interworking
        1. ET Networks Provided by PSTN
          1. Simple Business Line
          2. Centrex Line
          3. VPN
        2. Private ET Networks
          1. PBX Networks
          2. Tie-Lines for PBX Interconnection
      4. Summary
    3. 3. Basic Telephony Signaling
      1. Signaling Overview
        1. Analog and Digital Signaling
        2. Direct Current Signaling
        3. In-Band and Out-of-Band Signaling
        4. Loop-Start and Ground-Start Signaling
        5. CAS and CCS
      2. E&M Signaling
        1. Type I
        2. Type II
        3. Type III
        4. Type IV
        5. Type V
      3. CAS
        1. Bell System MF Signaling
          1. Supervision Signaling
          2. Analog Trunks
          3. Digital Trunks
          4. Address Signaling
        2. CCITT No. 5 Signaling
          1. Supervision Signaling
          2. Address Signaling
        3. R1
        4. R2
          1. Supervision Signaling on Analog Trunks
          2. CCITT-R2
          3. National R2
          4. Supervision Signaling on Digital Trunks
          5. Inter-Register Signaling
          6. Groups for Inter-Register Signaling
          7. Feature Support
      4. ISDN
        1. ISDN Services
        2. ISDN Access Interfaces
          1. BRI
          2. PRI
        3. ISDN L2 and L3 Protocols
          1. Q.931 Call Control Messages
        4. Basic ISDN Call
          1. Call Setup
          2. Call Disconnect
      5. QSIG
        1. QSIG Services
        2. QSIG Architecture and Reference Points
        3. QSIG Protocol Stack
        4. QSIG Basic Call Setup and Teardown Example
      6. DPNSS
      7. Summary
    4. 4. Signaling System 7
      1. SS7 Network Architecture
        1. Signaling Elements
          1. SSP
          2. STP
          3. Global Title Translation
          4. STP Hierarchy
          5. SCP
        2. Signaling Links
          1. Signaling Modes
          2. Signaling Links and Linksets
          3. Signaling Routes
          4. Signaling Link Performance
      2. SS7 Protocol Overview
        1. Physical Layer—MTP L1
        2. Data Layer—MTP L2
          1. FISU
          2. LSSU
          3. MSU
        3. Network Layer—MTP3
          1. Message Format
          2. SMH
          3. Routing Overview
          4. SNM Message Structure
          5. Congestion Control
          6. Rerouting
          7. Changeover and Changeback
        4. SCCP
          1. Connection-Oriented Services
          2. Connectionless Services and Messages
          3. SCCP Connectionless Example
          4. SCCP Management Functions
        5. TUP
        6. ISUP
          1. ISUP Services
          2. End-to-End Signaling
          3. Call Setup and Teardown
          4. ISUP Message Format
          5. ISUP Call Control Messages
        7. TCAP
          1. TCAP Interfaces
          2. Transaction Portion of TCAP
          3. Component Portion of TCAP
      3. SS7 Examples
        1. Basic Call Setup and Teardown Example
        2. 800 Database Query Example
      4. List of SS7 Specifications
      5. Summary
    5. 5. PSTN Services
      1. Plain Old Telephone Service
        1. Custom Calling Features
        2. CLASS Features
        3. Voice Mail
        4. Business Services
        5. Virtual Private Voice Networks
        6. Centrex Services
        7. Call Center Services
      2. Service Provider Services
        1. Database Services
        2. Operator Services
      3. Summary
  8. II. Voice over IP Technology
    1. 6. IP Tutorial
      1. OSI Reference Model
        1. The Application Layer
        2. The Presentation Layer
        3. The Session Layer
        4. The Transport Layer
        5. The Network Layer
        6. The Data Link Layer
        7. The Physical Layer
      2. Internet Protocol
      3. Data Link Layer Addresses
      4. IP Addressing
      5. Routing Protocols
        1. Distance-Vector Routing
        2. Link-State Routing
        3. BGP
        4. IS-IS
        5. OSPF
        6. IGRP
      6. EIGRP
        1. RIP
      7. IP Transport Mechanisms
        1. TCP
        2. UDP
      8. Summary
      9. References
    2. 7. VoIP: An In-Depth Analysis
      1. Delay/Latency
        1. Propagation Delay
        2. Handling Delay
        3. Queuing Delay
      2. Jitter
      3. Pulse Code Modulation
        1. What Is PCM?
        2. A Sampling Example for Satellite Networks
      4. Voice Compression
        1. Voice Coding Standards
        2. Mean Opinion Score
        3. Perceptual Speech Quality Measurement
      5. Echo
      6. Packet Loss
      7. Voice Activity Detection
      8. Digital-to-Analog Conversion
      9. Tandem Encoding
      10. Transport Protocols
        1. RTP
        2. Reliable User Data Protocol
      11. Dial-Plan Design
      12. End Office Switch Call-Flow Versus IP Phone Call
      13. Summary
      14. References
    3. 8. Quality of Service
      1. QoS Network Toolkit
      2. Edge Functions
        1. Bandwidth Limitations
        2. cRTP
        3. Queuing
          1. Weighted Fair Queuing
          2. Custom Queuing
          3. Priority Queuing
          4. CB-WFQ (CB=Class Based)
          5. PQ within CB-WFQ (Low Latency Queuing)
          6. Queuing Summary
        4. Packet Classification
          1. IP Precedence
          2. IP Precedence Caveats
          3. Resetting IP Precedence through Policy Routing
          4. Policy Routing
          5. RSVP
          6. RSVP Syntax
          7. RSVP Caveats
      3. Traffic Policing
        1. CAR
        2. Traffic Shaping
          1. Differences Between GTS and FRTS
          2. Traffic Shaping and Queuing
          3. GTS
          4. FRTS
          5. Fragmentation
          6. Blocking
          7. MCML PPP
          8. FRF.12
          9. IP MTU and MTU
          10. IP MTU Caveats
          11. MTU Caveats
        3. Edge QoS Wrap-Up
      4. Backbone Networks
        1. High-Speed Transport
          1. Modified Deficit Round Robin
        2. Congestion Avoidance
          1. WRED
          2. TCP
        3. Backbone QoS Wrap-Up
      5. Rules of Thumb for QoS
      6. Cisco Labs’ QoS Testing
      7. Summary
    4. 9. Billing and Mediation Services
      1. Billing Basics
        1. Authentication, Authorization, and Accounting (AAA)
        2. RADIUS
        3. Vendor-Specific Attributes (VSA)
        4. Billing Formats
          1. Typical Telco Approach
          2. Open Settlements Protocol (OSP)-Based Approach
          3. RADIUS-Based Approach
          4. IPDR-Based Approach
      2. Case Study: Cisco SIP Proxy Server and Billing
        1. RADIUS Server Accounting
          1. RADIUS Interface for Cisco SPS
          2. Prepaid and Postpaid Applications
      3. Challenges for VoIP Networks
      4. Mediation Services
      5. Summary
    5. 10. Voice Security
      1. Security Requirements
      2. Security Technologies
        1. Shared-Key Approaches
        2. Public-Key Cryptography
          1. Asymmetric Keys
          2. Digital Signature
          3. Certificates and Certificate Authority
          4. Public-Key-Based Protocols
          5. TLS
          6. IPsec
          7. SRTP
      3. Protecting Voice Devices
        1. Disabling Unused Ports/Services
        2. HIPS
      4. Protecting IP Network Infrastructure
        1. Segmentation
        2. Traffic Policing
        3. 802.1x Device Authentication
        4. Layer 2 Tools
          1. DHCP Snooping
          2. IP Source Guard
          3. Dynamic ARP Inspection
          4. CAM Overflow and Port Security
          5. BPDU Guard and Root Guard
          6. Circumventing VLANs
        5. NIPS
        6. Layer 3 Tools
          1. Authentication of Routing Updates
          2. TCP Intercept
      5. Security Planning and Policies
        1. Transitive Trust
        2. VoIP Protocol-Specific Issues
        3. Complexity Tradeoffs
        4. NAT/Firewall Traversal
        5. Password and Access Control
      6. Summary
  9. III. IP Signaling Protocols
    1. 11. H.323
      1. H.323 Elements
        1. Terminal
        2. Gateway
        3. Gatekeeper
        4. The MCU and Elements
        5. H.323 Proxy Server
      2. H.323 Protocol Suite
        1. RAS Signaling
          1. Gatekeeper Discovery
          2. Registration
          3. Endpoint Location
          4. Admissions
          5. Status Information
          6. Bandwidth Control
        2. Call Control Signaling (H.225)
        3. Media Control and Transport (H.245 and RTP/RTCP)
          1. Fast Connect Procedures
          2. Tunneling H.245
          3. Call Termination
          4. Media Transport (RTP/RTCP)
      3. H.323 Call-Flows
      4. Summary
    2. 12. SIP
      1. SIP Overview
        1. Functionality That SIP Provides
        2. SIP Network Elements
        3. Interaction with Other IETF Protocols
        4. Message Flow in SIP Network
      2. SIP Message Building Blocks
        1. SIP Addressing
        2. SIP Messages
          1. SIP Requests
          2. SIP Responses
          3. SIP Message Structure
          4. SIP Headers
        3. SIP Transactions and Dialog
        4. Transport Layer Protocols for SIP Signaling
      3. Basic Operation of SIP
        1. Proxy Server Example
        2. Redirect Server Example
        3. B2BUA Server Example
      4. SIP Procedures for Registration and Routing
        1. User Agent Discovering SIP Servers in a Network
        2. SIP Registration and User Mobility
        3. SIP Message Routing
        4. Routing of Subsequent Requests Within a SIP Dialog
        5. Signaling Forking at the Proxy
        6. Enhanced Proxy Routing
      5. SIP Extensions
        1. SIP Extension Negotiation Mechanism: Require, Supported, Allow Headers
        2. Caller and Callee Preferences
        3. SIP Event Notification Framework: Subscription and Notifications
        4. SUBSCRIBE and NOTIFY Methods
        5. Monitoring Registration State Using the Subscription-Notification Framework
        6. SIP REFER Request
        7. Presence and Instant Messaging Overview
        8. SIP Extensions for IM and Presence
      6. Summary
    3. 13. Gateway Control Protocols
      1. MGCP Overview
      2. MGCP Model
        1. Endpoints
        2. Connections
        3. Calls
      3. MGCP Commands and Messages
        1. CreateConnection (CRCX)
        2. ModifyConnection (MDCX)
        3. DeleteConnection (DLCX)
        4. NotificationRequest (RQNT)
        5. Notification (NTFY)
        6. AuditEndpoint (AUEP)
        7. AuditConnection (AUCX)
        8. RestartIn-Progress (RSIP)
        9. EndpointConfiguration (EPCF)
        10. MGCP Response Messages
      4. MGCP Call Flows
        1. Basic MGCP Call Flow
        2. Trunking GW-to-Trunking GW Call Flow
      5. Advanced MGCP Features
        1. Events and Event Packages
        2. Digit Maps
        3. Embedded Notification Requests
        4. Non-IP Bearer Networks
      6. H.248/MEGACO
      7. Summary
  10. IV. VoIP Applications and Services
    1. 14. PSTN and VoIP Interworking
      1. Cisco Packet Telephony
      2. Packet Voice Network Overview
        1. Network Elements
          1. Call Agent: PGW2200
          2. Media Gateway
          3. Service Control Point
          4. Cable Headend
        2. Residential Gateway
          1. H.323/SIP Endpoint/Client
        3. Network Interfaces
          1. Signaling Termination
          2. SS7 Links
          3. PRI Links
          4. CAS Links
          5. H.323
          6. Inter-PGW2200 Signaling
          7. Connection Control: MGCP
          8. Services Control
      3. PGW2200 Architecture and Operations
        1. PGW2200-Supported Protocols
        2. Execution Environment
        3. North American Numbering Plan
          1. Route Analysis
          2. Digit Analysis
          3. Reroute on Congestion
      4. PGW2200 Implementation
        1. Application Check-Pointing
        2. MGC Node Manager
        3. Accounting
      5. PSTN Signaling Over IP
        1. SCTP
        2. IUA
      6. Changing Landscape of PSTN-IP Interworking
      7. Session Border Controller (SBC)
      8. Summary
    2. 15. Service Provider VoIP Applications and Services
      1. The Service Provider Dilemma
      2. Service Provider Applications and Benefits
      3. Service Provider VoIP Deployment: Vonage
        1. VoIP Operational Advantages
      4. Service Provider Case Study: Prepaid Calling Card
        1. BOWIE.net Multiservice Networks
      5. Session Border Control: Value Addition
      6. VoIP Peering: Top Priority for the Service Providers
      7. Service Provider VoIP and Consumer Fixed Mobile Convergence
      8. Summary
    3. 16. Enterprise Voice over IP Applications and Services
      1. Migrating to VoIP Architecture
      2. Enterprise Voice Applications and Benefits
      3. Advanced Enterprise Applications
        1. Web-Based Collaboration and Conference
        2. The Need for Presence Information
        3. Presence-Aware Services
      4. Wi-Fi–Enabled Phones
      5. Better Voice Quality Using Wideband Codecs
      6. Summary