The current version of the Internet (known as version 4 or IPv4) uses a 32-bit IP addressing system, means Ipv4 can only produce address up to 2^32 i.e. in binary number system 32 times 1 i.e. 4,294,967,296. Even though we cannot use all these addresses because millions of addresses are reserved for private networks and multi cast addresses.
For example, the IP address 0.0.0.0 is reserved for the default network, the address 127.0.0.1 is used for loopback(localhost) address and the address 255.255.255.255 is used for broadcasts
If we compare this with our Postal system, this is similar to the postman can identify 4,294,967,296 correct home address but if more than these addresses are present then how postman can deliver a post??? So we need the postman who can identify more addresses than 4,294,967,296. This introduces out new addressing system call as Internet Protocol Version 6. IPv6 uses 128-bit addressing system, so IPv6 can produce 2^128 unique addresses i.e. 128 times 1
i.e. 340,282,366,920,938,463,463,374,607,431,768,211,456
The tremendous growth in mobile devices including cellular phones, notebooks, computers, and wireless handheld devices has created a need for additional blocks of IP addresses. The website http://www.internetworldstats.com/stats.htm shows 1,596,270,108 Internet users in the world by March 2009.One day it will cross the mark of our limited IP addresses(i.e. 4,294,967,296).Before the IP will be exhausted we should ready with the solution i.e. IPv6.Some organizations are predicting that IP will be exhausted in 2012 or 2013.
The Internet Engineering Task Force adopted "IP Next Generation" (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.
The following advantages are immediately obvious in the new scheme of things:
Þ Larger address space
Þ Support for mobile devices
Þ Simplified address auto-configuration
Þ Improved address management
Þ Built-in security with end-to end IP Sec
Þ Enables more levels of hierarchy for route aggregation
IPv6 addresses are normally written as eight groups of four hexadecimal digits, where each group is separated by a colon (:). For example,
2001:0db8:85a3:0000:0000:8a2e:0370:7334
IPv6 also implements new features that simplify aspects of address assignment (stateless address auto configuration) 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 an automatic mechanism for forming the host identifier from Link Layer media addressing information (MAC address).
The 2008 Summer Olympic Games were a notable event in terms of IPv6 deployment, being the first time a major world event has had a presence on the IPv6 Internet at http://ipv6.beijing2008.cn/en (IP addresses 2001:252:0:1::2008:6 and 2001:252:0:1::2008:8) and all network operations of the Games were conducted using IPv6.[29]It is believed that the Olympics provided the largest showcase of IPv6 technology since the inception of IPv6.
In 1997, IBM became the first commercial vendor to support IPv6 through its AIX 4.3 operating system. The latest version of Microsoft's Windows operating system, Windows Vista, has full IPv6 support enabled by default.