1.1. The History of IPv6
The Internet Engineering Task Force (IETF) began the effort to develop a successor protocol to IPv4 in the early 1990s. Several parallel efforts to solve the foreseen address space limitation and to provide additional functionality began simultaneously. The IETF started the Internet ProtocolNext Generation (IPng) area in 1993 to investigate the different proposals and to make recommendations for further procedures.
The IPng area directors of the IETF recommended the creation of IPv6 at the Toronto IETF meeting in 1994. Their recommendation is specified in RFC 1752, "The Recommendation for the IP Next Generation Protocol." The Directors formed an Address Lifetime Expectation (ALE) working group to determine whether the expected lifetime for IPv4 would allow the development of a protocol with new functionality, or if the remaining time would allow only the development of an address space solution. In 1994, the ALE working group projected that the IPv4 address exhaustion would occur sometime between 2005 and 2011 based on the available statistics.
For those of you who are interested in the different proposals, here's some more information about the process (from RFC 1752). There were four main proposals: CNAT, IP Encaps, Nimrod, and Simple CLNP. Three more proposals followed: the P Internet Protocol (PIP), the Simple Internet Protocol (SIP), and TP/IX. After the March 1992 San Diego IETF meeting, Simple CLNP evolved into TCP and UDP with Bigger Addresses (TUBA), and IP Encaps became IP Address Encapsulation (IPAE). IPAE merged with PIP and SIP and called itself Simple Internet Protocol Plus (SIPP). The TP/IX working group changed its name to Common Architecture for the Internet (CATNIP). The main proposals were now CATNIP, TUBA, and SIPP. For a short discussion of the proposals, refer to RFC 1752.
The Internet Engineering Steering Group approved the IPv6 recommendation and drafted a Proposed Standard on November 17, 1994. RFC 1883, "Internet Protocol, Version 6 (IPv6) Specification," was published in 1995. The core set of IPv6 protocols became an IETF Draft Standard on August 10, 1998. This included RFC 2460, which obsoleted RFC 1883.