What is IPv6?

IPv6 is short for "Internet Protocol Version 6". It is the "next generation" protocol designed by the IETF (Internet Engineering Task Force) to replace the current version Internet Protocol, IP Version 4 (IPv4).

Most of today's Internet and corporate networks use IPv4, which is now more than twenty years old. IPv4 has been remarkably resilient in spite of its age. In the early seventies, when IPv4 was originally developed, it was impossible to imagine the current size and speed of the Internet. It is amazing, that this protocol is still able to support the modern Internet.

Despite IPv4's long history it has a number of limitations. The most important limitation is the lack of address space. IPv4 addresses will run out in in the near future (current predictions are sometime between 2009 and 2011).

The IPv4 Internet would have run out of addresses many years ago if it had not been for the widespread deployment of technologies like NAT (Network Address Translation). However, but this is not a good long term solution and suffers from many undesirable side-effects.

By using the IPv6 address space of 128 bits (compared to 32 bits with IPv4), the limit on addresses has been extended from a theoretical 4 billion (232 = 4294967296) to 340 trillion (2128 = 3.4028236692093846346337460743177 x 1038).

Limited address space is not the only reason to move toward IPv6. The designers of IPv6 have learned from the many years of using IPv4. They kept all the strengths from IPv4 and added a lot of functionality which will be needed in our future networks. Of particular imnportance are the advanced autoconfiguration features that allow businesses to deploy a great array of new desktop, mobile and embedded network devices in a cost effective, controlled manner. Additionally, Mobility Enhancements will provide the foundation for new types of services.

IPv6 also adds many improvements to IPv4 in areas such as security, mobility, quality of service, scalability of the network architecure and routing. IPv6 is therefore very much suited for scalable and converged networks. A number of transition and coexistence mechanisms have been developed and are constantly improved in order to make the transition a smooth one. It is expected that IPv6 will gradually replace IPv4 within the following years, with the two protocols coexisting for many years during the transition period.

Unlike the "old" IPv4 addresses, IPv6 addresses are written in hex format and look like this 2001:0960:0002:0585:0000:0000:0000:0002 or, in shortened form, like this 2001:960:2:585::2.