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Managing IP Addresses
How to Number Your Network
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Bill Dutcher
• H M E H:: ? H E ^Wiley Computer Publishing
John Wiley & Sons, Inc.
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
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
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
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
J
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
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
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
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
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
