About IPv6
IPv6 is short for "Internet Protocol Version 6". IPv6 is designed to replace the current version Internet Protocol, IP Version 4 ("IPv4").
Most of today's internet uses IPv4, which is now nearly twenty years old. IPv4 has been remarkably resilient in spite of its age, but it is beginning to have problems. Most importantly, there is a growing shortage of IPv4 addresses, which are needed by all new machines added to the Internet.
IPv6 fixes a number of problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as routing and network autoconfiguration. IPv6 is expected to gradually replace IPv4, with the two coexisting for a number of years during a transition period.
IPv6 addresses are 128 bits long (as defined by RFC 4291), whereas IPv4 addresses are 32 bits. The IPv4 address space contains 4,294,967,296 addresses whereas IPv6 has enough room for 3.402823669x1038 unique addresses (this is approximately 5x1028 addresses for each of the roughly 6.5 billion people alive today).
Notation
IPv6 addresses are normally written as eight groups of four hexadecimal digits. For example,
2001:0db8:85a3:08d3:1319:8a2e:0370:7334
is a valid IPv6 address.
Support of IPv6
Linux: Fully supports IPv6 as of kernel version 2.6.10 (December 24, 2004) (Note: IPv6 was introduced much earlier, but 2.6.10 marks the date that it was officially certified by the IPv6 forum)
Windows: Suports IPv6 as of Windows XP SP1 (September 9, 2002)
