Building Switched Networks

Multilayer Switching, QoS, IP Multicast, Network Policy, and Service Level Agreements

Darryl P. Black

ADDISON-WESLEY An Imprint of Addison Wesley Longman, Inc.

Reading, Massachusetts • Harlow, England • Menlo Park, California Berkeley, California • Don Mills, Ontario • Sydney

Bonn • Amsterdam • Tokyo • Mexico City

Contents

Preface xiii Introduct ion xiii Organization of This Book xv Audience xvii Acknowledgments xviii

( Chapter 1 Our Demands for Networking 1

1.1 Introduct ion 1 1.2 Key Problems Addressed 1 1.3 Communication Paradigms 3 1.4 Examples of How We Use Networking Today 4 1.5 Today's Networks 5 1.6 Tomorrow's Networking Requirements 7 1.7 The Main Goal of Networking 8 1.8 Incorporating Fea tu res of Phone Networks 9 1.9 The Main Demands on Networking 11 1.10 Critical Components of Tomorrow 12 1.11 Behind the Scene Network Needs 14 1.12 Existing Pa t te rns 15 1.13 Sett ing Expectat ions 16 1.14 Conclusions 17

Chapter 2 Our Networking Base 19

2.1 Introduct ion 19 2.2 Key Solutions Offered 19 2.3 The Prerequisi te Information Challenge 20

2.3.1 The Chapter Two Road Map 20 2.4 The ISO OSI Reference Model 22

2.4.1 Layer 1: Physical 24 2.4.2 Layer 2: Data Link 24 2.4.3 Layer 3: Network 25 2.4.4 Layer 4: Transport 25 2.4.5 Layers 1,2, and 3 26

2.5 The Big Picture 27 2.6 Twisted Pair and Fiber 27 2.7 Connectionless versus Connection-Oriented 28

vii

viii Contents

2.8 Ethernet 30 2.8.1 Fast Ethernet 34 2.8.2 Gigabit Ethernet 35

2.9 ATM and ATM LANE 37 2.9.1 ATM LANE 40 2.9.2 Physical Topology in the LAN 40 2.9.3 Physical Topology in the WAN 42 2.9.4 Operation 42

2.10 Point-to-Point Connections and Cloud Technologies 43 2.10.1 X.25 44 2.10.2 Frame Relay 45

2.11 Bridging 46 2.12 Important TCP/IP Concepts 49

2.12.1 IP Addressing 51 2.13 What is DHCP? 52 2.14 Routing 53

2.14.1 Distance-Vector and Link-State Protocols 55 2.14.2 Routing in the LAN 57 2.14.3 Routing in the WAN 61

2.15 WWW and HTTP 67 2.16 Setting Expectations 68 2.17 Conclusions 69

Chapter 3 Switching Technology 71

3.1 Introduction 71 3.2 Key Solutions Offered 72 3.3 Switching Comes from the Telephone Network 72 3.4 Switches Are "Designed" for the LAN or WAN 74 3.5 Switch Components 75 3.6 Switch Implementations 76 3.7 LAN Switching 78

3.7.1 Collision Domains and Broadcast Domains 79 3.7.2 Switched LANs 80 3.7.3 Types of LAN Switches 81

3.8 WAN Switching 83 3.8.1 WAN Protocols 83 3.8.2 Types of WAN Switches 85

3.9 Packet and Cell Switching Technologies 88 3.9.1 ATM Switching 88 3.9.2 Frame Relay Switching 89

Contents ix

3.9.3 FDDI and Token Ring Switching 90 3.9.4 Ethernet, Fast Ethernet, and Gigabit Switching 90

3.10 Gigabit Ethernet and ATM 91 3.11 WhatisaVLAN? 92 3.12 VLAN Creation Techniques 94 3.13 VLAN Advantages 97 3.14 VLAN Disadvantages 97 3.15 What is Tagging? 99

3.15.1 Tag Header Organization 100 3.15.2 802.1Q 102 3.15.3 802.1p 103

3.16 Setting Expectations 104 3.17 Conclusions 106

Chapter 4 Multilayer Switching 107

4.1 Introduction 107 4.2 Key Solutions Offered 108 4.3 Routers Can Be Traffic Bottlenecks 109 4.4 Multilayer Switching in a Nutshell 110 4.5 Layer-2 Switching 113 4.6 Layer-3 Switching 114 4.7 Layer-4 Switching 115 4.8 Fast IP and NHRP 116 4.9 Multiprotocol over ATM (MPOA) 118 4.10 Routing Combined with Connection-Oriented Services 120 4.11 Label-Based Switching 121

4.11.1 The IETF MPLS Effort 123 4.11.2 MPLS Functional Requirements 124 4.11.3 Important MPLS Terminology 125 4.11.4 Key Features of MPLS 125 4.11.5 How MPLS Works 129 4.11.6 Label Management 131 4.11.7 Label Assignment: Local versus Egress Control 132 4.11.8 Tunneling 133 4.11.9 MPLS Challenges 133

4.12 Tag Switching 136 4.13 IP Navigator 140 4.14 ARIS 141 4.15 Cell Switched Routers (CSR) 145 4.16 IP Switching 146

X Contents

4.17 Setting Expectations 148 4.18 Conclusions 149

Chapter 5 Guaranteed Delivery 151

5.1 Introduction 151 5.2 Key Solutions Offered 152 5.3 When Does Delay Matter? 153 5.4 What Causes Delay, Anyway? 153 5.5 Resource Sharing 159 5.6 Overprovision, Precedence, Dedicated Resource 160 5.7 The Guaranteed Reservation Paradox 162 5.8 Quality of Service (QoS) Basics 163

5.8.1 What is QoS, Anyway? 163 5.9 Traffic Management 168

5.9.1 Buffer Management 168 5.9.2 Bandwidth Management and Queues 168 5.9.3 Traffic Management Control 170 5.9.4 Random Early Discard (RED) 172

5.10 The ATM World 172 5.10.1 ATM's Built-in QoS 173 5.10.2 ATM Service Classes 173

5.11 The IP World 175 5.11.1 Resource ReSerVation Protocol (RSVP) 178

5.12 Integrating ATM with RSVP 185 5.13 Type of Service (TOS), OSPF, QOSPF, and QoS 185 5.14 WinSock2 187 5.15 IPv6 188 5.16 Setting Expectations 190 5.17 Conclusions 191

Chapter 6 Multicast in the Network 193

6.1 Introduction 193 6.2 Key Solutions Offered 193 6.3 IP Multicast in a Nutshell 194 6.4 Internet Group Management Protocol (IGMP) 198 6.5 Distance-Vector Multicast Routing Protocol (DVMRP) 199 6.6 Multicast Open Shortest Path First (MOSPF) 199 6.7 Core-Based Trees (CBT) 201

Contents xi

6.8 Protocol Independent Multicast 203 6.8.1 Dense Mode (PIM-DM) 203 6.8.2 Sparse Mode (PIM-SM) 205

6.9 Multicast over ATM (MARS) 206 6.10 IETF Developments 206

6.10.1 Multicast-Border Gateway Protocol (M-BGP) 206 6.10.2 Multicast Reliability 207

6.11 Setting Expectations 208 6.12 Conclusions 208

Chapter 7 Network Policy and Services 211

7.1 Introduction 211 7.2 Key Solutions Offered 212 7.3 Network Policy 212

7.3.1 Service Level Agreements (SLAs) 213 7.4 Policy—The Distributed Glue That Ties

Everything Together 214 7.5 Network Configuration Repositories 215

7.5.1 Next Steps for DHCP 216 7.5.2 Remote Authentication Dial-In User Service (RADIUS) 216 7.5.3 An Example of RADIUS in Use 217

7.6 Introducing Distributed Policy Is a Large Challenge 219 7.6.1 Lightweight Directory Access Protocol (LDAP) 219 7.6.2 Directory Enabled Networking (DEN) 223

7.7 Network Services 227 7.7.1 Virtual Private Networks (VPNs) 227

7.8 Interactive Voice over Data Networks 235 7.8.1 Voice over Data Challenges 237 7.8.2 Deploying Interactive Voice over an Intranet 238 7.8.3 Network Services Depend on Network Policy 239

7.9 Real-Time Video over Data Networks 239 7.10 Setting Expectations 240 7.11 Conclusions 241

Chapter 8 Managing Our Demands for Networking 243

8.1 Introduction 243 8.2 Key Problems Addressed 243

XÜ Contents

8.3 The Basics of Management 244 8.3.1 The Sources of Network Management Data 245

8.4 Engineering Problem Solving Applied to Network Management 246

8.5 Switched Networks Challenge Network Management 249 8.5.1 Layered Management 250 8.5.2 Hierarchical Management 253 8.5.3 Distributed Management 253 8.5.4 DHL Management 254

8.6 Network Management Needs of Switched Networks 255 8.6.1 Proactive versus Reactive Management 256 8.6.2 Robustness 256 8.6.3 Scalability 256 8.6.4 Security 257 8.6.5 Traffic Management 257 8.6.6 Delivery Guarantees and Traffic Prioritization 257 8.6.7 Traffic Optimization 258

8.7 Twelve Cardinal Rules of Creating Management Solutions 258

8.8 Policy-Based Network Management 260 8.9 A Conceptual View of Managing Tomorrow's

Switching Solutions 261 8.10 Management Strives to Be End-to-End 262 8.11 Preparing for New Switching Solutions 263 8.12 Setting Expectations 264 8.13 Conclusions 267

Bibliography 269

Networking Acronyms Used in This Book 273

Index 287