What is IPv6

According to Wikipedia, IPv6 is the next-generation Internet Layer protocol for packet-switched internetworks and the Internet. IPv4 is currently the dominant Internet Protocol version, and was the first to receive widespread use. In December 1998, the Internet Engineering Task Force (IETF) designated IPv6 as the successor to version 4 by the publication of a Standards Track specification, RFC 2460.

In December 2008, despite celebrating its 10-year anniversary as a Standards Track protocol, IPv6 was only in its infancy in terms of general world-wide deployment. Recent studies indicate that penetration is still less than one percent of Internet traffic in any country. The leaders are Russia (0.76%), France (0.65%), Ukraine (0.64%), Norway (0.49%), and the United States (0.45%). Although Asia leads in terms of absolute deployment numbers, the relative penetration is smaller (e.g., China: 0.24%). IPv6 is implemented on all major operating systems in use in commercial, business, and home consumer environments. According to the Google study, Mac OS leads in IPv6 penetration of 2.44%, followed by Linux (0.93%) and Windows Vista (0.32%).

IPv6 has a much larger address space than IPv4. This is based on the definition of a 128-bit address, whereas IPv4 used only 32 bits. The new address space thus supports 2128 (about 3.4×1038) addresses. This expansion provides flexibility in allocating addresses and routing traffic and eliminates the need for network address translation (NAT). NAT gained wide-spread deployment as an effort to alleviate IPv4 address exhaustion.

IPv6 also implements new features that simplify aspects of address assignment (stateless address autoconfiguration) and network renumbering (prefix and router announcements) when changing Internet connectivity providers. The IPv6 subnet size has been standardized by fixing the size of the host identifier portion of an address to 64 bits to facilitate automatic mechanism for forming the host identifier from Link Layer media addressing information (MAC address).

Network security is integrated by design in the IPv6 architecture. Internet Protocol Security (IPsec) was originally developed for IPv6, but found wide-spread optional deployment first in IPv4 into which it was re-engineered. The IPv6 specifications mandate IPsec implementation as a fundamental interoperability requirement.

The general requirements for implementing IPv6 on a network host are specified in RFC 4294.

MOTIVATION OF IPV6

The first publicly-used version of the Internet Protocol, Version 4 (IPv4), provides an addressing capability of about 4 billion addresses (2³²). This was deemed sufficient in the design stages of the early Internet when the explosive growth and worldwide distribution of networks were not anticipated.

During the first decade of operation of the TCP/IP-based Internet, by the late 1980s, it became apparent that methods had to be developed to conserve address space. In the early 1990s, even after the introduction of classless network redesign, it was clear that this was not enough to prevent IPv4 address exhaustion and that further changes to the Internet infrastructure were needed. By the beginning of 1992, several proposed systems were being circulated, and by the end of 1992, the IETF announced a call for white papers (RFC 1550) and the creation of the "IP Next Generation" (IPng) area of working groups.

The Internet Engineering Task Force adopted IPng on July 25, 1994, with the formation of several IPng working groups. By 1996, a series of RFCs were released defining Internet Protocol Version 6 (IPv6), starting with RFC 2460.

Incidentally, the IPng architects could not use version number 5 as a successor to IPv4, because it had been assigned to an experimental flow-oriented streaming protocol (Internet Stream Protocol), similar to IPv4, intended to support video and audio.

It is widely expected that IPv4 will be supported alongside IPv6 for the foreseeable future. IPv4-only nodes are not able to communicate directly with IPv6 nodes, and will need assistance from an intermediary.

Reference(s):
http://en.wikipedia.org/wiki/IPv6