Chapter 8. IP Version 6

This chapter covers the following key topics:

• Design Goals of IPv6 ” This section covers IPv6's design goals: enable scalable networks, ease configuration, and maintain security.

• Current State of IPv6 ” This section covers the standards and drafts that are available, vendor support or announced support, and customer-driven applications that will begin demanding its implementation.

• IPv6 Packet Format ” This section covers the IPv6 packet format, which includes the large, hierarchical IPv6 addresses and headers that enable routers to efficiently process the packet.

• IPv6 Functionality ” This section covers IPv6 functionality, including automatic router discovery, dead neighbor detection, automatic host configuration, and multicasting capabilities.

• Transition from IPv4 to IPv6 ” IPv4 will exist for a long time. This section covers transition mechanisms (including dual stacks, tunnels, and address/protocol translation) that ease the transition to IPv6 and enable coexistence.

IP version 6 (IPv6) is designed to be the new generation of the IP protocol, following IP version 4. The number 5 had already been assigned to another Internet protocol, the Internet Stream Protocol, version II, as defined in RFC 1190. A detailed description of all IPv6 components is beyond the scope of this book, but this chapter thoroughly summarizes the design goals of IPv6 and the current state of the protocol. This chapter also covers IPv6 packet format, IPv6 functionality, and methods to get from IPv4 internetworks to IPv6 internetworks. The Cisco router configurations shown in this chapter are created using beta software that is based on IOS 12.0. Commands may be modified, added, or deleted, and output may be modified in the final version of the code, although any changes will probably be minimal. Cisco has announced that the production code will be in a later version of Cisco IOS Software Release 12.1.