Development of IPv6 by the Internet Engineering Task Force (IETF) began in 1993,
in response to a series of perceived problems, primarily the exhaustion of the
current, IP version 4 (IPv4), address space.
It arose out of an evaluation and design process that began in 1990 and
considered a number of options and a range of different protocol alternatives.
The design process was essentially complete, and a protocol specified, in the
first half of 1995, although related work continues.
The current version of the specification was published, after considerable
implementation experience had been obtained, at the end of 1998. However, a
number of other changes were made in formats and the interpretation of data
fields. Those changes are intended to make the network operate better in the
long term and to expand options for the design of efficient protocols, but their
presence makes transition more complex than it would have been with address
space expansion alone.
Until a few years ago, some communities argued that IPv4 address space
exhaustion would not happen, or would be avoided. But now, there is now general
consensus that measures should be taken urgently to deal with the growing
scarcity of IPv4 address space.
More tutorial material is available at the ‘Articles & Documents’.