Introduction

Introduced by the IETF in 1992, IPv6 appears today to be a fundamental and well-engineered solution to the IPv4 addressing space shortage. IPv6 is significantly more efficient than IPv4 because its design is based on the past 20 years experience of the IPv4 protocol.

With IPv6, we have to change our thinking, because this protocol was not only designed for computers on networks such as the current IPv4 Internet. The applicability of IPv6 is global to communication devices such as cellular, wireless, phones, PDAs, television, radio, and so on rather than being limited to computers.

One main goal of IPv6 is to make the router the key element of any network by simplifying the deployment, operation, and management of any IP-based network. Moreover, IPv6 is more advanced and scalable than IPv4 for global networks that will be made with billions of nodes, such as the 3G infrastructure. Some advantages of IPv6 are a larger address space, a simpler header, autoconfiguration, renumbering, aggregation, multihoming, transition, and coexistence with the existing IPv4 infrastructure.

In the long term, Internet gurus and high-level analysts agree that the Internet must be upgraded to IPv6. In fact, the ultimate goal of IPv6 is to completely replace IPv4. Therefore, the long-term market for IPv6 is huge, representing billions of nodes and networks all around the world.

Cisco Systems, Inc., is the world's leading supplier of internetworking hardware and software. Cisco has been involved in IETF IPv6 standardization since 1995, at the early stages of IPv6's design. Because Cisco technology carries about 80% of all Internet traffic, Cisco is obviously a key player in the worldwide deployment of IPv6.

This Book's Objectives

Understanding the technical mechanisms of IPv6, the new IPv6 features available on Cisco IOS Software technology, and the interoperability between the Cisco routers and IPv6 implementations are fundamental to deploying scalable and reliable IPv6 networks.

Therefore, this book gives you a strong view of the Cisco IPv6 implementations, as well as an in-depth technical reference regarding designing, configuring, deploying, and debugging IPv6 on Cisco routers. You will gain expertise in IPv6 on Cisco technology through practical examples of all the IPv6 features presented in this book.

Who Should Read This Book

This book is intended for professionals in the enterprise and provider markets such as architects, network designers, systems engineers, network managers, administrators, and any technical staff. Professionals who are planning to use Cisco technology to deploy IPv6 networks, provide IPv6 connectivity, and use IPv6 within their network backbones need this book. You will find this book valuable because it provides many examples, figures, IOS commands, and tips for using IPv6 with Cisco IOS Software technology.

You will find everything you need to describe, design, configure, support, and operate IPv6 network backbones based on Cisco routers. To get the most out of this book, you need a minimal background in IPv4 and should be able to operate Cisco routers.

How This Book Is Organized

Although you could read this book cover-to-cover, it is designed to be flexible. You can easily move between chapters and sections to cover just the material you need more work with.

The book is divided into five parts. The first part explains the history of IPv6, the rationale behind it, and its benefits. The second part presents in detail the basic and advanced features of IPv6. Then it explains designing, enabling, configuring, and routing IPv6 networks using Cisco IOS Software technology. The third part describes the main integration and coexistence mechanisms and demonstrates integrating IPv6 on the current IPv4 infrastructure using different strategies. This part shows you examples of internetworking using Cisco IOS Software technology with different host implementations supporting IPv6. The fourth part describes the 6bone design and how this worldwide IPv6 backbone is operated. It also provides information that helps ISPs undertand the steps and rules of becoming an IPv6 provider on the IPv6 Internet. The fifth part contains the appendixes and a glossary.

The following list highlights the topics covered and the book's organization:

• Part I: Overview of and Justification for IPv6

  Chapter 1, “Introduction to IPv6”— This chapter introduces and provides an overview of the new IPv6 protocol. More specifically, it discusses the rationale of IPv6 by presenting the issues of IPv4 such as IPv4 address space exhaustion, the fast-growing global Internet routing table, and the many implications of using network address translation (NAT) mechanisms. This chapter also presents the history of IPv6 and provides an overview of IPv6 features such as larger address space, addressing hierarchy, aggregation, autoconfiguration, network renumbering, efficient headers, mobility, security, and the transition from IPv4 networks to IPv6.

• Part II: IPv6 Design

  Chapter 2, “IPv6 Addressing”— This chapter discusses the fundamentals of IPv6 and explains the application of basic IPv6 configurations on Cisco routers. More specifically, this chapter describes in detail the new IPv6 header, the IPv6 addressing architecture, the upper-layer protocols UDP and TCP, the representation of IPv6 addresses, and all types of addresses scoped in IPv6 such as link-local, site-local, and many others. This chapter also explains and provides examples of enabling IPv6 on a router, enabling and assigning IPv6 addresses to network interfaces, using the EUI-64 format to configure addresses, and verifying IPv6 configurations on interfaces.

  Chapter 3, “IPv6 in Depth” — This chapter is the key chapter of the book, because it describes IPv6's advanced features and mechanisms such as Neighbor Discovery Protocol (NDP), stateless autoconfiguration, prefix advertisement, duplicate address detection (DAD), the replacement of ARP, Internet Control Message Protocol for IPv6 (ICMPv6), path MTU discovery (PMTUD), the new AAAA record for the domain name system (DNS), DHCPv6, IPSec, and Mobile IPv6. Then, to help you acquire strong practical knowledge of these advanced IPv6 features, Chapter 3 covers enabling and managing prefix advertisement on Cisco, renumbering a network, and defining IPv6 standard and extended access control lists (ACLs). It also provides examples of verifying, managing, and debugging IPv6 configurations on Cisco routers using IPv6-enabled tools and commands such as show, debug, ping, traceroute, Telnet, ssh, and TFTP which are EXEC commands of the IOS.

  Chapter 4, “Routing on IPv6”— This chapter explains the differences between the EGP and IGP routing protocols for IPv6 by comparing them to their IPv4 equivalents. As in IPv4, routing protocols are fundamental for the IPv6 routing domains. Chapter 4 starts by presenting an overview of the updates and changes applied on these routing protocols to support IPv6. This chapter covers the interdomain routing protocol BGP4+ and the intradomain routing protocols RIPng, IS-IS for IPv6, and OSPFv3. This chapter also discusses and provides examples of enabling, configuring, and managing these IPv6 routing protocols on Cisco routers. More pratically, it covers configuring static and default IPv6 routes, enabling and configuring BGP4+ with IPv6, establishing multihop BGP4+ configuration, configuring BGP4+ to exchange IPv4 routes between BGP IPv6 peers, configuring prefix filtering and route maps for IPv6 with BGP4+, using link-local addresses with BGP4+, configuring RIPng, enabling and configuring IS-IS and OSPFv3 for IPv6, and redistributing IPv6 routes into BGP4+, RIPng, and IS-IS for IPv6 and OSPFv3. The last section of the chapter presents the commands used in Cisco Express Forwarding for IPv6 (CEFv6). It also describes managing some of these routing protocols using the show and debug commands.

• Part III: IPv4 and IPv6: Coexistence and Integration

  Chapter 5, “IPv6 Integration and Coexistence Strategies”— This chapter covers the main integration and coexistence strategies provided in IPv6 to maintain complete backward compatibility with IPv4 and to allow a smooth transition from IPv4 to IPv6. The integration and coexistence strategies presented in this chapter include the dual-stack approach; the multiple protocols and techniques of tunneling IPv6 packets over IPv4 networks, such as configured tunnel, tunnel broker, tunnel server, 6to4, GRE tunnel, ISATAP, and automatic IPv4-compatible tunnel; and IPv6-only-to-IPv4-only transition mechanisms such as the application-level gateway and NAT-PT. In addition, this chapter covers enabling the dual stack, enabling a configured tunnel, enabling 6to4, using a 6to4 relay, deploying IPv6 over GRE, enabling ISATAP tunnels, enabling NAT-PT, and applying static and dynamic NAT-PT configurations. This chapter also provides examples of verifying and debugging some of these transition techniques.

  Chapter 6, “IPv6 Hosts Internetworking with Cisco”— This chapter covers enabling and configuring IPv6 support on Microsoft Windows NT, 2000, and XP; Solaris 8; FreeBSD 4.x; Linux; and Tru64 UNIX to internetwork with Cisco IOS Software technology. You see examples of internetworking using stateless autoconfiguration, the dual-stack approach, configured tunnel, and 6to4 between the IPv6 host implementations and Cisco routers.

• Part IV: The IPv6 Backbone

  Chapter 7, “Connecting to the IPv6 Internet”— This chapter discusses how the IPv6 Internet is built and how to be connected to it. More specifically, this chapter describes the architecture, design, addressing, and routing policy of the 6Bone and how to become a pseudo-TLA on that IPv6 backbone. It also covers policy allocation and how addresses are allocated on the production IPv6 Internet by regional Internet registries (RIRs). It lists the criteria to become an IPv6 provider and describes address allocation, the reassignment of addresses to customers, and how providers may deploy IPv6 connectivity to their customers.

• Part V: Appendixes

  Appendix A, “Cisco IOS Software IPv6 Commands”— This appendix lists commands of the Cisco IOS Software technology that are available for IPv6 and that are presented in this book.

  Appendix B, “Answers to Review Questions”— This appendix provides the answers to each chapter's review questions. The answers to the case study questions can be found at the end of each chapter.

  Appendix C, “RFCs Related to IPv6”— This appendix lists IETF RFCs that explore the technical specifications of IPv6.

  Glossary— This element provides definitions of new technical terms introduced by IPv6.

Icons Used in This Book

Command Syntax Conventions

The conventions used to present command syntax in this book are the same conventions used in the IOS Command Reference. It describes these conventions as follows:

• Vertical bars (|) separate alternative, mutually exclusive elements.

• Square brackets ([ ]) indicate an optional element.

• Braces ({ }) indicate a required choice.

• Braces within brackets ([{ }]) indicate a required choice within an optional element.

• Bold indicates commands and keywords that are entered literally as shown. In configuration examples and output (not general command syntax), bold indicates commands that are manually input by the user (such as a show command).

• Italic indicates arguments for which you supply actual values.