Table of Contents

Contents

PREFACE

CHAPTER 1 Addressing and Subnetting Basics

IP Address Basics

Classful Addressing-Structure and Size of Each Type

What Is a Network?

Class A

Class B

Class C

Address Assignments

Single Address per Interface

Multihomed Devices

Multinetting-Multiple Addresses per Interface

Examples

Purpose of Subnetting

The Basic Fixed-Length Mask

What the Mask Does

Components of a Mask

Binary Determination of Mask Values

Decimal Equivalent Mask Values

Creating Masks for Various Networking Problems

Addresses and Mask Interaction

Reserved and Restricted Addresses

Determining the Range of Addresses within Subnets

Determining Subnet Addresses Given a Single Address and Mask

Interpreting Masks

Reserved Addresses

Summary

FAQs

CHAPTER 2 Creating an Addressing Plan for Fixed-Length Mask Networks

Introduction

Determine Addressing Requirements

Review Your Internetwork Design

How Many Subnets Do You Need?

How Many IP Addresses Are Needed in Each Subnet?

What about Growth?

Choose the Proper Mask

Consult the Tables

Use Unnumbered Interfaces

Ask for a Bigger Block of Addresses

Router Tricks

Use Subnet Zero

Obtain IP Addresses

From Your Organization's Network Manager

From Your ISP

From Your Internet Registry

Calculate Ranges of IP Addresses for Each Subnet

Doing It the Hard Way

Worksheets

Subnet Calculators

Allocate Addresses to Devices

Assigning Subnets

Assigning Device Addresses

Sequential Allocation

Reserved Addresses

Grow Towards the Middle

Document Your Work

Keeping Track of What You've Done

Paper

Spreadsheets

Databases

In Any Case

Summary

FAQs

Exercises

Subnetting Tables

Class A Subnetting Table

Class B Subnetting Table

Class C Subnetting Table

Subnet Assignment Worksheet

CHAPTER 3 Private Addressing and Subnetting Large Networks

Introduction

Strategies to Conserve Addresses

CIDR

VLSM

Private Addresses

Addressing Economics

An Appeal

Public vs Private Address Spaces

Can I Pick My Own?

RFC 1918-Private Network Addresses

The Three-Address Blocks

Considerations

Which to Use When

Strategy for Subnetting a Class A Private Network

The Network

The Strategy

Address Assignment

The Headquarters LANs

The WAN Links from Headquarters to
the Distribution Centers

The Distribution Center LANs

The WAN Links from the DC to the Stores

The Store LANs

Results

Summary

FAQs

Exercises

CHAPTER 4 Network Address Translation

Introduction

Hiding Behind the Router/Firewall

What Is NAT?

How Does NAT Work?

Network Address Translation (Static)

How Does Static NAT Work?

Double NAT

Problems with Static NAT

Configuration Examples

Windows NT 2000

Cisco IOS

Linux IP Masquerade

Network Address Translation (Dynamic)

How Does Dynamic NAT Work?

Problems with Dynamic NAT

Configuration Examples

Cisco IOS

Port Address Translation (PAT)

How Does PAT Work?

Problems with PAT

Configuration Examples

Windows NT 2000

Linux IP Masquerade

Cisco IOS

What Are the Advantages?

What Are the Performance Issues?

Proxies and Firewall Capabilities

Packet Filters

Proxies

Stateful Packet Filters

Stateful Packet Filter with Rewrite

Why a Proxy Server Is Really Not a NAT

Shortcomings of SPF

Summary

FAQs

References & Resources

RFCs

IP Masquerade/Linux

Cisco

Windows

NAT Whitepapers

Firewalls

CHAPTER 5 Variable-Length Subnet Masking

Introduction

Why Are Variable-Length Masks Necessary?

Right-sizing Your Subnets

More Addresses or More Useful Addresses?

The Importance of Proper Planning

Creating and Managing Variable-Length Subnets

Analyze Subnet Needs

Enumerate Each Subnet and Number of Required Nodes

Determine Which Mask to Use in Each Subnet

Allocate Addresses Based on Need For Each Subnet

Routing Protocols and VLSM

Class C VLSM Problem

Completing the Class C Problem

Template-based Address Assignment

Summary

FAQs

CHAPTER 6 Routing Issues

Introduction

Classless Interdomain Routing

From Millions to Thousands of Networks

ISP Address Assignment

Using CIDR Addresses Inside Your Network

Contiguous Subnets

IGRP

EIGRP

EIGRP Concepts

RIP-1 Requirements

Comparison with IGRP

Routing Update Impact

RIP-2 Requirements

OSPF

Configuring OSPF

Routing Update Impact

OSPF Implementation Recommendations

BGP Requirements

IBGP and EBGP Requirements

Loopback Interfaces

Summary

FAQs

CHAPTER 7 Automatic Assignment of IP Addresses with BOOTP and DHCP Objectives

Introduction

The Role of Dynamic Address Assignment

A Brief History

Address Management with These Tools

The BOOTP Packet

Field Descriptions and Comments

OP

HTYPE

HLEN

HOPS

XID

SECS

FLAG

CIADDR

YIADDR

SIADDR

GIADDR

CHADDR

SNAME

FILE

VEND/OPTION

BOOTP Process Details

Client BOOTREQUEST

Server BOOTREPLY

Field Values in the BOOTREPLY packet

The BOOTP Server Database

How Does DHCP Work?

DHCP Process Overview

DHCP Process Details

DHCP-Specific Options

Interoperation between DHCP and BOOTP

DHCP Address Scopes

Comparing BOOTP and DHCP

How BOOTP Works

BOOTP Process Overview

DHCP / BOOTP Options

BOOTP Options from RFC1497

IP Layer Parameters per Host

IP Layer Parameters per Interface

Link Layer Parameters per Interface

TCP Parameters

Application and Service Parameters

BOOTP, DHCP, and Routed Networks

The BOOTP Relay Agent

The Role of the GIADDR

Other Fields Involved

HOPS

CHADDR, YIADDR, HTYPE, HLEN, FLAG

SECS

UDP Port Number

IP TTL Field

ALL Other Fields

BOOTP Implementation Checklist

DHCP Implementation Checklist

Summary

FAQs

CHAPTER 8 Multicast Addressing

What Is Multicast?

Mapping IP Multicast to the Link Layer

Joining the Group

IGMP

Multicast Routing Protocols

Mbone

Multicast Addresses

Transient and Permanent Addresses

Generic Assignments

IANA Assignments

Scope of Multicast Addresses Using TTL

Administrative Scopes

IP Stacks and Multicast

Why Multicast?

Efficiency of Bandwidth Usage and Scaling

Discovering

Efficient Channel

Industry

Summary

FAQ

References

CHAPTER 9 IPv6 Addressing

Introduction

IPv6 Addressing Basics

IPv6 Addressing Scheme Characteristics

Version

Traffic Class

Flow Label

Payload Length

Next Header

Hop-by-Hop Options Header

Destination Options Header I

Routing Header

Fragment Header

Authentication Header

Encrypted Security Payload Header

Destination Options Header II

Hop Limit

Source Address

Destination Address

More Bits!

A More Flexible Hierarchical Organization of Addresses

FP: Format Prefix

TLA ID

RES

NLA ID

SLA ID

Interface ID

Minimizing the Size of Routing Tables

Global Addresses for the Internet and Local Addresses for Intranet

IPv6 Benefits

Increased IP Address Size

Increased Addressing Hierarchy Support

Simplified Host Addressing

Simpler Autoconfiguration of Addresses

Improved Scalability of Multicast Routing

The Anycast Address

The Need for Further Development

The Multihoming Problem

The 6Bone

Summary

FAQ

CHAPTER 10 The IPv6 Header

Introduction

Expanded Addressing

Simplified Header

Improved Support for Extension and Option

Flow and Flow Labeling

Authentication and Privacy

IPv6 Header

IPv4 Header

Extension Headers

Hop-by-Hop Option Header

Routing Header

Fragment Header

Authentication Header

Encapsulating Security Payload

Destination Options Header

Upper-Layer Protocol Issues

Summary

FAQs

References

APPENDIX A Address Assignment

Introduction

Registries

Provider-Based Assignments

Cost of an IP Address

How to Find an IPv4 Address Delegation

How to Find an IPv6 Address Delegation

Internet Governance

Summary

INDEX