Managing IP Addresses

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Managing IP Addresses

How to Number Your Network

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Bill Dutcher

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Wiley Computer Publishing

John Wiley & Sons, Inc.

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Acknowledgments xi ...

Introduction xiii Chapter 1 Whaf s an IP Address? 1

The IP Protocol 3 IP Addresses and Classes 5

Class A Addresses 7 Class B Addresses 8 Class C Addresses 9 Class D and E Addresses 9 Making Life Easier for Binary-Challenged Humans 10

Identifying a Type of Network Address 11

The Working Classes 13 Hosts and Interfaces 13

Summary 14

Chapter 2 The Politics of IP Address Delegation 17

What Is Delegation? 18

IANA 19 Expanding the Task 20

Winding It Down 22 IRs and the ISPs 24 The ISP Viewpoint 25 The Future of IRs 26

Summary 28

Chapter 3 Global Internet Routing 31

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iv Contents

Chapter 4

It Takes a URL

To Connect or Not to Connect Top-Level Routing

IP Routing Principles Routing Tables The Hop Count Link Weight Inside, Outside

Interior and Exterior Routing Protocols ASes and CIDR

CIDR

Simplifying Routing An Imperfect World

Managing the Load CIDR Masks

Groups ofCs

Enforcing the Rules Summary

Why Renumber?

Reasons for Renumbering Internal Factors

Cleaning Up Legacy Routing Documenting Incomplete Networks Joining Networks with Business Partners Outgrowing Address Space

Moving to Private Address Space Virtual LANs (VLANs)

External Factors

Changing ISPs

Provider-Independent Address Space

Aggregating Several Small Networks into Large CIDR Blocks Nonunique Addresses Swampland Reclamation Network Expansion Ipv6 36 37 40 41 42 44 45 45 47 49 50 51 52 52 53 54 58 59 61 62 63 63 63 64 64 65 65 66 66 67 68 68 69 71 71 Drawbacks of Renumbering 72 Summary 72

Chapter 5 Making the Business Case for Renumbering 75

The Business Case 76 What's in a Business Case? 76

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Composing the Business Case 78 Justifying an Address Space Request 79

IP Address Space Value 80

Apply Yourself 81 Current Address Usage 81

Future Address Usage 82

Summary 84

Chapter 6 Diagrams and Documentation 85

Dependencies 86 Preparing the Surface 86

Site Plans 86 Existing Networks (LANs and WANs) 87

Routing 88 External WAN Links 89

Current Addressing Plan 90

Types of Addresses in Use 90

Unaggregated or Unaggregatable Addresses 91

Private Address Space 92

Subnetworks 93 Business Partner Address Ranges 93

Network Expansion Plans 94 Available Address Ranges 94

ISP Connections 95 Router Layout and Connectivity 95

Interior and Exterior Routing Protocols 96

Firewalls and NAT 97 Intrusion Detection Systems (IDS) 98

Proxy Servers 98 Dial-Up Access or Remote Access Service (RAS) 99

Domain Name Service (DNS) 99

Applications 100 Hosts and Printers 101

Summary 102

Chapter 7 Subnetworking 103

Less Wasted Space 104 The Basics of Subnetworking 106

IP Addresses and IP Routers 107 Subnetworks and Addresses 108

Stockpiling Subnets 111

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vi Contents

Chapter 8

Chapter 9

Beneath the Byte Boundary Subnetwork Masks

Class C Subnetworks All-Zeroes, All-Ones

Variable Length Subnetwork Masking (VLSM) Summary

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Network Address Translation

The Need for NAT NAT Basics Why NAT?

NAT for Security NAT for Proxy Services

NAT for Private Address Space NAT for Routability

NAT for Business Partners How NAT Works

Only by Proxy Positioning NAT NAT'S Dark Side NAT and TCP

That TCP Port Thing TCP Ports

Establishing the Connection Back to the Ports

To Connect or Not to Connect Summary

DNS Considerations

The DNS Database

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Chapter 10 Provider-Aggregated and Provider-Independent

Address Space 163

Independent and Aggregated 164 Provider-Aggregated Address Space 164

Provider-Independent Address Space 166

Private Address Space 167 Maybe You Can Take It with You 168

I Want My PI 169 The New PI Rules 170 Do I Need an Autonomous System Number? 171

Getting PI 172 Summary 173

Chapter 11 Host Considerations 175

A Host Is a Host 176 HOSTS File 176 WINS and NetBIOS 177

Unix System Configuration Files 178 Readdressing with Configuration Files 179

DHCP 180 DHCP Server, Where Are You? 180

DHCP Scope 181 Displaying DHCP-Assigned Address Information 182

Configuring a PC to Use DHCP 182 Hosts with Multiple Interfaces 183 Ethernet Switch Problems 184 The DHCP Downside 185 Summary 186 187 188 190 192 193 195 196 198 199 Chapter .

12 You and Your ISP

Stub Networks

Multiconnected Networks Multihomed Networks Primary and Backup Sharing the Load Transit Networks

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viii Contents

Chapter 13 You as ISP

Drawing the Line of Demarcation Address Space Route Aggregation Static Routes Multihoming Autonomous Systems DNS Documentation Summary 201 202 203 204 205 206 207 210 214 215

Chapter 14 Renumbering Routers

Router Interfaces Serial Ports LAN Interfaces Secondary Addresses

Additional Network Addresses Separated Addresses

Transition from Bridged Networks

Loopback Address Terminal Ports Dial-Up Port Pools DHCP Services

DNS Implications for Router Renumbering Authentication Server Access

Summary

Chapter 15 Renumbering Steps

Process Steps

Plan Renumbering Effort

Get Address Allocation Assignment Establish Current Address Usage Determine Address Usage

Get Address Assignments

Update and Upgrade DNS Servers Changing NS Addresses

Changing the SOA

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Reset DNS Services 245 Do Administrative Cleanup 246

Summary 246

Chapter 16 Small Network Case Study 247

Situation 248 Scoping the Project 249

Project Plan 249 Preparing for Renumbering 251

Addressing Rollout 251 Administrative Cleanup 252

Future Growth 253 Summary 254

Chapter 17 Medium Network Case Study 255

Situation 255 Scoping the Problem 258

Project Plan 259 DNS 261 DHCP 261 Preparing for Renumbering 261

Addressing Rollout 263 Administrative Cleanup 264

Future Growth 265 Summary 265

Chapter 18 Large Network Case Study 267

Situation 268 Scoping the Problem 271

Project Plan 272 Preparing for Renumbering 274

Addressing Rollout 275 Administrative Cleanup 276

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X Contents

Chapter 19

-The Future of IP

The Trouble with IPv4

Killing Me Softly with New Apps Feelings of Insecurity

Once and Future Solutions Quality of Service

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