Tài liệu Designing for cisco internetwork solution

Authorized Self-Study Guide Designing for Cisco Internetwork Solutions (DESGN) Second Edition Diane Teare Cisco Press 800 East 96th Street Indianapolis, IN 46240 USA ii Authorized Self-Study Guide Designing for Cisco Internetwork Solutions (DESGN), Second Edition Diane Teare Copyright© 2008 Cisco Systems, Inc. Published by: Cisco Press 800 East 96th Street Indianapolis, IN 46240 USA All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher, except for the inclusion of brief quotations in a review. Printed in the United States of America First Printing October 2007 Library of Congress Cataloging-in-Publication Data: Teare, Diane. Designing for Cisco internetwork solutions (DESGN) / Diane Teare. -- 2nd ed. p. cm. -- (Authorized self-study guide) Rev. ed. of: CCDA self-study : designing for Cisco internetwork solutions (DESGN) / Diane Teare. c2004. "Exam 640-863." ISBN-13: 978-1-58705-272-9 (hardcover) ISBN-10: 1-58705-272-5 (hardcover) 1. Computer networks--Examinations--Study guides. 2. Telecommunications engineers--Certification. 3. Internetworking (Telecommunication)--Examinations--Study guides. I. Title. II. Series. TK5105.5.T418 2008 004.6--dc22 2007032855 ISBN-13: 978-1-58705-272-9 ISBN-10: 1-58705-272-5 Warning and Disclaimer This book is designed to provide information about designing Cisco networks. Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied. The information is provided on an “as is” basis. The author, Cisco Press, and Cisco Systems, Inc. shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book or from the use of the discs or programs that may accompany it. The opinions expressed in this book belong to the author and are not necessarily those of Cisco Systems, Inc. iii Trademark Acknowledgments All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Cisco Press or Cisco Systems, Inc., cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. Corporate and Government Sales The publisher offers excellent discounts on this book when ordered in quantity for bulk purchases or special sales, which may include electronic versions and/or custom covers and content particular to your business, training goals, marketing focus, and branding interests. For more information, please contact: U.S. Corporate and Government Sales 1-800-382-3419 [email protected] For sales outside the United States please contact: International Sales [email protected] Feedback Information At Cisco Press, our goal is to create in-depth technical books of the highest quality and value. Each book is crafted with care and precision, undergoing rigorous development that involves the unique expertise of members from the professional technical community. Readers’ feedback is a natural continuation of this process. If you have any comments regarding how we could improve the quality of this book, or otherwise alter it to better suit your needs, you can contact us through email at [email protected]. Please make sure to include the book title and ISBN in your message. We greatly appreciate your assistance. Publisher: Paul Boger Cisco Representative: Anthony Wolfenden Associate Publisher: Dave Dusthimer Cisco Press Program Manager: Jeff Brady Executive Editor: Brett Bartow Development Editor: Eric Stewart Managing Editor: Patrick Kanouse Copy Editor: Mike Henry Senior Project Editor: Tonya Simpson Technical Editors: Shawn Boyd and Richard Piquard Editorial Assistant: Vanessa Evans Proofreader: Gayle Johnson Designer: Louisa Adair Composition: Mark Shirar Indexer: Ken Johnson iv About the Author Diane Teare is a professional in the networking, training, and e-learning fields. She has more than 20 years of experience in designing, implementing, and troubleshooting network hardware and software and has also been involved in teaching, course design, and project management. She has extensive knowledge of network design and routing technologies and is an instructor with one of the largest authorized Cisco Learning Partners. She was recently the Director of e-Learning for the same company, where she was responsible for planning and supporting all the company’s e-learning offerings in Canada, including Cisco courses. Diane has a bachelor’s degree in applied science in electrical engineering (BASc) and a master’s degree in applied science in management science (MASc). She is a certified Cisco instructor and currently holds her CCNP and CCDP certifications. She coauthored the Cisco Press titles Campus Network Design Fundamentals, the three editions of Building Scalable Cisco Internetworks (BSCI), and Building Scalable Cisco Networks. She also edited the first edition of this book and Designing Cisco Networks. About the Technical Reviewers Shawn Boyd is a senior network consultant for ARP Technologies, Inc. He has worldwide experience in consulting on many different projects, such as security/VoIP for Cisco Systems Israel, intrusion prevention for Top Layer Networks of Boston, and DSL infrastructure rollout for Telus Canada. Shawn is also active in course development and is a certified Cisco instructor with ARP Technologies, Inc., responsible for teaching most of the Cisco curriculum. He has coauthored IT security–related books for Cisco Press and has been a technical editor on a few Cisco Press Self-Study Guides. His background is in network security and design at a service provider level. He has worked for Canada’s largest telco providers, performing network designs and implementations, and was lead contact on many large government contracts. Richard Piquard is a senior network architect for Global Knowledge Network, Inc. He has more than seven years of experience as a certified Cisco instructor, teaching introductory and advanced routing, switching, design, and voice-related courses throughout North America and Europe. Richard has a highly diverse skill set in design and implementation of both Cisco and multivendor environments. His experience in the industry ranges from his military background as the network chief of the Marine Corps Systems Command, Quantico, Virginia, to a field engineer for the Xylan Corporation (Alcatel), Calabasas, California, to a member of a four-person, worldwide network planning and implementation team for the Household Finance Corporation, Chicago. v Dedications This book is dedicated to my wonderful husband, Allan Mertin, whose optimism inspires me; to our captivating son, Nicholas, and his enthusiastic curiosity and quest for knowledge; to my parents, Syd and Beryl, for their continuous love and support; and to my friends, including “the Girls,” for continuing to help me keep my sanity! Acknowledgments I would like to thank the many people who helped put this book together, including the following: The Cisco Press team—Brett Bartow, the executive editor, for driving this book through the process, and his continued support over the years. Vanessa Evans was instrumental in organizing the logistics and administration. Eric Stewart, the development editor, has been invaluable in producing a high-quality manuscript. I would also like to thank Tonya Simpson for her excellent work in shepherding this book through the editorial process. Thanks also to Richard Froom, Balaji Sivasubramanian, and Erum Frahim, the authors of Cisco Press’s Building Cisco Multilayer Switched Networks (BCMSN), Fourth Edition. The Cisco Systems team—Many thanks to the members of the team who developed the latest version of the DESGN course. The team included two people from Chesapeake Netcraftsmen: Carole Warner Reece and Peter Welcher. Members of the team from Cisco Systems included Dennis Masters, Dwayne Fields, Pat Lao, Bill Chadwick, Bob Eckoff, Bob Ligett, Drew Blair, and the project manager, Dan Stern. The technical reviewers—I would like to thank the technical reviewers of this book, Shawn Boyd and Richard Piquard, for their comprehensive, detailed review and beneficial input. My family—Of course, this book would not have been possible without the constant understanding and tolerance of my family, who have lived through the many weekends and nights it took to complete it. Special thanks to Nicholas for always making sure I got lots of hugs! vi vii Contents at a Glance Foreword xxvi Introduction xxvii Chapter 1 Network Fundamentals Review 3 Chapter 2 Applying a Methodology to Network Design Chapter 3 Structuring and Modularizing the Network Chapter 4 Designing Basic Campus and Data Center Networks Chapter 5 Designing Remote Connectivity Chapter 6 Designing IP Addressing in the Network Chapter 7 Selecting Routing Protocols for the Network Chapter 8 Voice Network Design Considerations Chapter 9 Wireless Network Design Considerations Chapter 10 Evaluating Security Solutions for the Network 57 129 221 293 377 429 479 565 651 Appendix A Answers to Review Questions and Case Studies Appendix B IPv4 Supplement Appendix C Open System Interconnection (OSI) Reference Model Appendix D Network Address Translation Acronyms and Abbreviations Index 888 725 807 871 859 845 viii Contents Foreword xxvi Introduction xxvii Chapter 1 Network Fundamentals Review 3 Introduction to Networks 3 Protocols and the OSI Model 4 The OSI Model 5 Protocols 6 The OSI Layers 6 Physical Layer—Layer 1 7 Data Link Layer—Layer 2 7 Network Layer—Layer 3 7 Transport Layer—Layer 4 8 Upper Layers—Layers 5 Through 7 9 Communication Among OSI Layers 9 LANs and WANs 11 Network Devices 13 Terminology: Domains, Bandwidth, Unicast, Broadcast, and Multicast Hubs 14 Switches 14 Routers 16 Introduction to the TCP/IP Suite 17 TCP/IP Transport Layer Protocols 18 Port Numbers 20 TCP Sequencing, Acknowledgment, and Windowing 21 TCP/IP Internet Layer Protocols 24 Protocols 25 IP Datagrams 25 TCP/IP-Related Data Link Layer Protocol 27 Routing 27 Routers Work at the Lower Three OSI Layers 28 Routing Tables 29 Routing Protocols 31 Addressing 31 Physical Addresses 31 Logical Addresses 32 Routing and Network Layer Addresses 33 IP Addresses 34 IP Address Classes 34 Private and Public IP Addresses 35 Subnets 36 13 ix Switching Types 38 Layer 2 Switching 38 Layer 3 Switching 41 Spanning Tree Protocol 42 Redundancy in Layer 2 Switched Networks STP Terminology and Operation 43 STP Terminology 43 STP States 45 Rapid STP 47 Virtual LANs 47 VLAN Membership 48 Trunks 49 STP and VLANs 49 Inter-VLAN Routing 51 Comprehensive Example 52 Summary 55 Chapter 2 42 Applying a Methodology to Network Design 57 The Cisco Service Oriented Network Architecture 57 Business Drivers for a New Network Architecture 57 Intelligence in the Network 58 Cisco SONA Framework 60 Network Design Methodology 64 Design as an Integral Part of the PPDIOO Methodology 64 Benefits of the Lifecycle Approach to Network Design 66 Design Methodology 67 Identifying Customer Requirements 69 Assessing the Scope of a Network Design Project 69 Identifying Required Information 70 Extracting Initial Requirements 70 Gathering Network Requirements 71 Planned Applications and Network Services 73 Organizational Goals 75 Organizational Constraints 78 Technical Goals 80 Technical Constraints 81 Characterizing the Existing Network and Sites 83 Customer Input 83 Sample Site Contact Information 84 Sample High-Level Network Diagram 86 Auditing or Assessing the Existing Network 87 Tools for Assessing the Network 89 Manual Information Collection Examples 90 Automatic Information Collection Examples 94 x Analyzing Network Traffic and Applications 95 Tools for Analyzing Traffic 96 NBAR 97 NetFlow 98 Other Network Analysis Tools Examples 101 Network Health Checklist 102 Summary Report 103 Creating a Draft Design Document 104 Time Estimates for Performing Network Characterization 105 Using the Top-Down Approach to Network Design 107 The Top-Down Approach to Network Design 107 Top-Down Approach Compared to Bottom-Up Approach 108 Top-Down Design Example 108 Decision Tables in Network Design 110 Structured Design 112 Network Design Tools 114 Building a Prototype or Pilot Network 115 Documenting the Design 116 The Design Implementation Process 117 Planning a Design Implementation 117 Implementing and Verifying the Design 119 Monitoring and Redesigning the Network 119 Summary 120 References 120 Case Study: ACMC Hospital Network Upgrade 121 Case Study Scenario 121 Organizational Facts 121 Current Situation 122 Plans and Requirements 124 Case Study Questions 124 Review Questions 125 Chapter 3 Structuring and Modularizing the Network 129 Network Hierarchy 129 Hierarchical Network Model 129 Hierarchical Network Design Layers 129 Access Layer Functionality 131 The Role of the Access Layer 131 Layer 2 and Multilayer Switching in the Access Layer Access Layer Example 133 Distribution Layer Functionality 134 The Role of the Distribution Layer 134 Distribution Layer Example 136 132 xi Core Layer Functionality 136 The Role of the Core Layer 137 Switching in the Core Layer 137 Hierarchical Routing in the WAN 139 Using a Modular Approach to Network Design 140 Evolution of Enterprise Networks 140 Cisco SONA Framework 141 Functional Areas of the Cisco Enterprise Architecture 141 Guidelines for Creating an Enterprise Network 145 Enterprise Campus Modules 146 Campus Infrastructure Module 148 Building Access Layer 148 Building Distribution Layer 148 Campus Core Layer 149 Server Farm Module 149 Enterprise Campus Guidelines 150 Enterprise Edge Modules 150 E-commerce Module 152 Internet Connectivity Module 152 Remote Access and VPN Module 153 WAN and MAN and Site-to-Site VPN Module 154 Enterprise Edge Guidelines 154 Service Provider Modules 155 Internet Service Provider Module 156 PSTN Module 156 Frame Relay/ATM Module 156 Remote Enterprise Modules 157 Enterprise Branch Module 157 Enterprise Data Center Module 158 Enterprise Teleworker Module 158 Services Within Modular Networks 159 Interactive Services 159 Security Services in a Modular Network Design 162 Internal Security 162 External Threats 166 High-Availability Services in a Modular Network Design 169 Designing High Availability into a Network 169 High Availability in the Server Farm 170 Designing Route Redundancy 173 Designing Link Redundancy 175 Voice Services in a Modular Network Design 177 Two Voice Implementations 177 IP Telephony Components 178 Modular Approach in Voice Network Design 179 Evaluating the Existing Data Infrastructure for Voice Design 181 xii Wireless Services in a Modular Network 181 Centralized WLAN Components 182 Application Networking Services in a Modular Network Design ANS Examples 184 ANS Components 184 Network Management Protocols and Features 186 Network Management Architecture 186 Protocols and Standards 187 SNMP 188 SNMPv1 189 SNMPv2 190 SNMPv3 191 MIB 192 MIB-II 194 Cisco MIB 195 MIB Polling Guidelines 195 MIB Example 196 RMON 197 RMON1 198 RMON1 Groups 198 RMON1 and RMON2 199 RMON2 Groups 200 Netflow 202 NetFlow Versus RMON Information Gathering 204 CDP 205 CDP Information 206 How CDP Works 206 Syslog Accounting 207 Syslog Distributed Architecture 210 Summary 211 References 212 Case Study: ACMC Hospital Modularity 212 Review Questions 215 Chapter 4 Designing Basic Campus and Data Center Networks Campus Design Considerations 221 Designing an Enterprise Campus 221 Network Application Characteristics and Considerations 222 Peer-Peer Applications 222 Client–Local Server Applications 223 Client–Server Farm Applications 224 Client–Enterprise Edge Applications 226 Application Requirements 227 Environmental Characteristics and Considerations 228 Network Geography Considerations 228 Transmission Media Considerations 230 183 221 xiii Infrastructure Device Characteristics and Considerations 235 Convergence Time 236 Multilayer Switching and Cisco Express Forwarding 237 IP Multicast 239 QoS Considerations in LAN Switches 241 Load Sharing in Layer 2 and Layer 3 Switches 244 Enterprise Campus Design 245 Enterprise Campus Requirements 246 Building Access Layer Design Considerations 246 Managing VLANs and STP 247 Managing Trunks Between Switches 251 Managing Default PAgP Settings 252 Implementing Routing in the Building Access Layer 252 Building Distribution Layer Design Considerations 253 Using First-Hop Redundancy Protocols 254 Deploying Layer 3 Routing Protocols Between Building Distribution and Campus Core Switches 255 Supporting VLANs That Span Multiple Building Access Layer Switches 257 Campus Core Design Considerations 257 Large Campus Design 259 Small and Medium Campus Design Options 260 Edge Distribution at the Campus Core 261 Server Placement 263 Servers Directly Attached to Building Access or Building Distribution Layer Switches 264 Servers Directly Attached to the Campus Core 264 Servers in a Server Farm Module 264 Server Farm Design Guidelines 266 Server Connectivity Options 267 The Effect of Applications on Switch Performance 267 Enterprise Data Center Design Considerations 268 The Enterprise Data Center 268 The Cisco Enterprise Data Center Architecture Framework 269 Enterprise Data Center Infrastructure 272 Data Center Access Layer 274 Data Center Aggregation Layer 274 Data Center Core Layer 275 Density and Scalability of Servers 276 Summary 276 References 277 Case Study: ACMC Hospital Network Campus Design 277 Case Study Additional Information 278 Case Study Questions 279 Review Questions 289 xiv Chapter 5 Designing Remote Connectivity 293 Enterprise Edge WAN Technologies 293 Introduction to WANs 293 WAN Interconnections 294 Traditional WAN Technologies 295 Packet-Switched Network Topologies 296 WAN Transport Technologies 298 TDM (Leased Lines) 299 ISDN 300 Frame Relay 300 Asynchronous Transfer Mode 301 MPLS 301 Metro Ethernet 304 DSL Technologies 304 Cable Technology 308 Wireless Technologies 309 Synchronous Optical Network and Synchronous Digital Hierarchy 311 Dense Wavelength Division Multiplexing 313 Dark Fiber 314 WAN Transport Technology Pricing and Contract Considerations 314 WAN Design 316 Application Requirements of WAN Design 317 Response Time 318 Throughput 318 Packet Loss 318 Reliability 318 Technical Requirements: Maximum Offered Traffic 319 Technical Requirements: Bandwidth 320 Evaluating the Cost-Effectiveness of WAN Ownership 321 Optimizing Bandwidth in a WAN 322 Data Compression 322 Bandwidth Combination 324 Window Size 324 Queuing to Improve Link Utilization 325 Congestion Avoidance 329 Traffic Shaping and Policing to Rate-Limit Traffic Classes 330 Using WAN Technologies 332 Remote Access Network Design 332 VPN Design 333 VPN Applications 333 VPN Connectivity Options 334 Benefits of VPNs 337 WAN Backup Strategies 338 Dial Backup Routing 338 Permanent Secondary WAN Link 338 Shadow PVC 340 xv The Internet as a WAN Backup Technology 341 IP Routing Without Constraints 341 Layer 3 Tunneling with GRE and IPsec 341 Enterprise Edge WAN and MAN Architecture 343 Enterprise Edge WAN and MAN Considerations 344 Cisco Enterprise MAN and WAN Architecture Technologies 345 Selecting Enterprise Edge Components 348 Hardware Selection 348 Software Selection 348 Cisco IOS Software Packaging 348 Cisco IOS Packaging Technology Segmentation 351 Comparing the Functions of Cisco Router Platforms and Software Families 351 Comparing the Functions of Multilayer Switch Platforms and Software Families 352 Enterprise Branch and Teleworker Design 352 Enterprise Branch Architecture 353 Enterprise Branch Design 355 Small Branch Office Design 356 Medium Branch Office Design 359 Large Branch Office Design 360 Enterprise Teleworker (Branch of One) Design 362 Summary 364 References 365 Case Study: ACMC Hospital Network WAN Design 366 Case Study Additional Information 366 Business Factors 367 Technical Factors 367 Case Study Questions 368 Review Questions 372 Chapter 6 Designing IP Addressing in the Network 377 Designing an IP Addressing Plan 377 Private and Public IPv4 Addresses 377 Private Versus Public Address Selection Criteria 378 Interconnecting Private and Public Addresses 379 Guidelines for the Use of Private and Public Addresses in an Enterprise Network Determining the Size of the Network 381 Determining the Network Topology 382 Size of Individual Locations 383 Planning the IP Addressing Hierarchy 384 Hierarchical Addressing 384 Route Summarization 384 IP Addressing Hierarchy Criteria 386 Benefits of Hierarchical Addressing 386 Summarization Groups 387 Impact of Poorly Designed IP Addressing 388 380 xvi Benefits of Route Aggregation 389 Fixed- and Variable-Length Subnet Masks 390 Routing Protocol Considerations 391 Classful Routing Protocols 391 Classless Routing Protocols 393 Hierarchical IP Addressing and Summarization Plan Example 394 Methods of Assigning IP Addresses 395 Static Versus Dynamic IP Address Assignment Methods 396 When to Use Static or Dynamic Address Assignment 396 Guidelines for Assigning IP Addresses in the Enterprise Network 397 Using DHCP to Assign IP Addresses 398 Name Resolution 400 Static Versus Dynamic Name Resolution 400 When to Use Static or Dynamic Name Resolution 401 Using DNS for Name Resolution 401 DHCP and DNS Server Location in a Network 403 Introduction to IPv6 404 IPv6 Features 405 IPv6 Address Format 406 IPv6 Address Types 408 IPv6 Address Scope Types 408 Interface Identifiers in IPv6 Addresses 409 IPv6 Unicast Addresses 410 Global Aggregatable Unicast Addresses 411 Link-Local Unicast Addresses 411 IPv6 Address Assignment Strategies 412 Static IPv6 Address Assignment 412 Dynamic IPv6 Address Assignment 413 IPv6 Name Resolution 414 Static and Dynamic IPv6 Name Resolution 414 IPv4- and IPv6-Aware Applications and Name Resolution 414 IPv4-to-IPv6 Transition Strategies and Deployments 415 Differences Between IPv4 and IPv6 415 IPv4-to-IPv6 Transition 416 Dual-Stack Transition Mechanism 416 Tunneling Transition Mechanism 417 Translation Transition Mechanism 418 IPv6 Routing Protocols 419 RIPng 420 EIGRP for IPv6 420 OSPFv3 421 Integrated IS-IS Version 6 421 BGP4+ 422 xvii Summary 422 References 423 Case Study: ACMC Hospital IP Addressing Design Review Questions 426 Chapter 7 423 Selecting Routing Protocols for the Network 429 Routing Protocol Features 429 Static Versus Dynamic Routing 430 Static Routing 430 Dynamic Routing 431 Interior Versus Exterior Routing Protocols 432 IGP and EGP Example 432 Distance Vector Versus Link-State Versus Hybrid Protocols Distance Vector Example 435 Link-State Example 436 Routing Protocol Metrics 438 What Is a Routing Metric? 438 Metrics Used by Routing Protocols 439 Routing Protocol Convergence 441 RIPv2 Convergence Example 442 Comparison of Routing Protocol Convergence 443 Flat Versus Hierarchical Routing Protocols 444 Flat Routing Protocols 444 Hierarchical Routing Protocols 445 Routing Protocols for the Enterprise 446 EIGRP 446 EIGRP Terminology 447 EIGRP Characteristics 449 OSPF 449 OSPF Hierarchical Design 450 OSPF Characteristics 451 Integrated IS-IS 453 Integrated IS-IS Terminology 453 Integrated IS-IS Characteristics 455 Summary of Interior Routing Protocol Features 455 Selecting an Appropriate Interior Routing Protocol 456 When to Choose EIGRP 457 When to Choose OSPF 457 Border Gateway Protocol 457 BGP Implementation Example 459 External and Internal BGP 460 Routing Protocol Deployment 461 Routing Protocols in the Enterprise Architecture 461 Routing in the Campus Core 461 Routing in the Building Distribution Layer 463 433 xviii Routing in the Building Access Layer 463 Routing in the Enterprise Edge Modules 464 Route Redistribution 464 Using Route Redistribution 465 Administrative Distance 466 Selecting the Best Route 467 Route Redistribution Direction 467 Route Redistribution Planning 468 Route Redistribution in the Enterprise Architecture 468 Route Filtering 470 Redistributing and Filtering with BGP 470 Route Summarization 471 The Benefits of Route Summarization 471 Recommended Practice: Summarize at the Distribution Layer 471 Recommended Practice: Passive Interfaces for IGP at the Access Layer Summary 474 References 474 Case Study: ACMC Hospital Routing Protocol Design 475 Review Questions 475 Chapter 8 Voice Network Design Considerations 479 Traditional Voice Architectures and Features 479 Analog and Digital Signaling 479 The Analog-to-Digital Process 480 Time-Division Multiplexing in PSTN 482 PBXs and the PSTN 483 Differences Between a PBX and a PSTN Switch 484 PBX Features 485 PSTN Switches 486 Local Loops, Trunks, and Interswitch Communications 487 Telephony Signaling 489 Telephony Signaling Types 490 Analog Telephony Signaling 491 Digital Telephony Signaling 491 PSTN Numbering Plans 495 International Numbering Plans 495 Call Routing 496 Numbering Plans 496 Integrating Voice Architectures 500 Introduction to Integrated Networks 500 Drivers for Integrating Voice and Data Networks 502 H.323 503 Introduction to H.323 503 H.323 Components 503 H.323 Example 507 473 xix Introduction to IP Telephony 508 IP Telephony Design Goals 509 Single-Site IP Telephony Design 510 Multisite WAN with Centralized Call Processing Design 511 Multisite WAN with Distributed Call Processing Design 513 Call Control and Transport Protocols 514 Voice Conversation Protocols 515 Call Control Functions with H.323 516 Call Control Functions with the Skinny Client Control Protocol Call Control Functions with SIP 518 Call Control Functions with MGCP 520 Voice Issues and Requirements 521 Voice Quality Issues 521 Packet Delays 521 Fixed Network Delays 522 Variable Network Delays 524 Jitter 526 Packet Loss 527 Echo 527 Voice Coding and Compression 529 Coding and Compression Algorithms 530 Voice Coding Standards (Codecs) 530 Sound Quality 531 Codec Complexity, DSPs, and Voice Calls 532 Bandwidth Considerations 533 Reducing the Amount of Voice Traffic 533 Voice Bandwidth Requirements 534 Codec Design Considerations 536 QoS for Voice 536 Bandwidth Provisioning 538 Signaling Techniques 538 Classification and Marking 538 Congestion Avoidance 539 Traffic Policing and Shaping 539 Congestion Management: Queuing and Scheduling 539 Link Efficiency 541 CAC 541 Building Access Layer QoS Mechanisms for Voice 544 AutoQoS 545 Introduction to Voice Traffic Engineering 545 Terminology 546 Blocking Probability and GoS 546 Erlang 547 CCS 547 Busy Hour and BHT 547 CDR 548 516