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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)       9  TCP/IP Internet Layer (OSI Network Layer) Protocols            9  Internet Protocol (IP/IPv4, IPng/IPv6) and IP-Related Protocols (IP NAT, IPSec, Mobile IP)                 9  Internet Protocol Version 6 (IPv6) / IP Next Generation (IPng)

Transition from IPv4 to IPv6 1 IPv6 Addressing Overview: Addressing Model and Address Types

The primary motivation for creating IPv6 was to rectify the addressing problems in IPv4. More addresses were required, but more than this, the IPv6 designers desired a way of interpreting, assigning and using them that was more consonant with modern internetworking. Based on this, it's no surprise that many of the changes in IPv6 are associated with IP addressing. The IPv6 addressing scheme is similar in general concept to IPv4 addressing, but has been completely overhauled to create an addressing system capable of supporting continued Internet expansion and new applications for the foreseeable future.

This section describes the concepts and methods associated with addressing under IPv6. I begin with a look at some addressing generalities in version 6, including the addressing model, address types size and address space. I discuss the unique and sometimes confusing representations and notations used for IPv6 addresses and prefixes. Then I look at how addresses are arranged and allocated into types, beginning with an overall look at address space composition and then the global unicast address format. I describe the new methods used for mapping IP addresses to underlying physical network addresses. I then describe special IPv6 addressing issues, including reserved and private addresses, IPv4 address embedding, anycast and multicast addresses, and autoconfiguration and renumbering of addresses.

Addressing under IPv6 is outlined in the main IPv6 RFC, RFC 2460 (Internet Protocol, Version 6 (IPv6) Specification). However, most of the details of IPv6 addressing are contained in two other standards: RFC 3513 (Internet Protocol Version 6 (IPv6) Addressing Architecture) and RFC 3587 (IPv6 Global Unicast Address Format). These replaced the 1998 standards RFC 2373 (IP Version 6 Addressing Architecture) and RFC 2374 (An IPv6 Aggregatable Global Unicast Address Format).

Transition from IPv4 to IPv6 1 IPv6 Addressing Overview: Addressing Model and Address Types