Last year some estimates for running out of IPv4 based addresses was placed in 2012. Today as a result of a huge increase in demand by Asia for Internet numbers John Curran, CEO at the American Registry for Internet Numbers is moving the date to as early as mid next year. In any case, ISPs and companies that have put off preparing for IPv6 will have to do so quickly. Moreover, they will need to support it and IPv4 for many years until the older addressing scheme is phased out. It is necessary to support both schemes as doing only one or the other will result in certain sites and users losing access to the Internet.
In the simplest of terms, IPv6 is intended to resolve the issue of the world running out of IP address in 2011. IPv4 is based upon a 32-bit address scheme whereas IPv6 uses 128 bits. The difference is dramatic. With IPv4, the Internet has a total IP address capacity of 4 billion unique addresses. In 1980 when IPv4 was released this seemed like a big number, as the engineering groups involved did not foresee the eventual growth that defines today's Internet. IPv6 represents 3.4x1038 or 340 trillion, trillion, trillion addresses. I think that might last the planet earth for a while. Other elements of IPv6 include improved security, simpler processing, mobility features and multicast.
As a result of the recession and focus on spending cuts many companies and ISPs are not ready for IPv6.
Curran suggests that ISPs begin offering IPv6 now in anticipation to exhausting the current numbers.
The effort will be worth it as the trillions of addresses available under the IPv6 scheme will certainly last beyond the life of what we know today as the Internet.