What is it?
Internet Protocol version 6 (IPv6) has been designed by the Internet Engineering Task Force to replace the current IP version 4 network layer protocol in the TCP/IP communications standard.
Most of the internet uses IPv4, which is now nearly 20 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 that connect to the internet.
IPv6 fixes a number of problems in IPv4, such as the limited number of available addresses. It also adds improvements in areas such as routing and network auto-configuration.
Some US government agencies, including the Department of Defense, have set a deadline of 2008 for moving to IPv6, and China, Japan and Korea are all committed to it.
But the commercial world needs to be convinced that the "evolutionary" benefits are worth the expense and upheaval.
Some carriers are installing dual-protocol networks, but the best prediction is that IPv6 will not begin to displace IPv4 until current networks come up for replacement, when the transition cost (estimated at up to £43bn worldwide) can be absorbed. Even then, they will coexist for a long time.
Where did it originate?
IPv6 was invented at Xerox Parc and adopted by the Internet Engineering Task Force in 1994. In 2004, the Internet Corporation for Assigned Names and Numbers announced the internet's root domain name system servers had been modified to support IPv6.
What is it for?
IPv4, with 32-bit address spaces, provides 4,000 million addresses - fewer than the number of people on the planet and largely collared by the developed world at the expense of emerging economies. Stanford University and the Massachusetts Institute of Technology between them have more IP addresses than the whole of China.
IPv6 introduces 128-bit addresses, expanding the potential number to trillions to take account of a world filled with internet-enabled devices.
IPv6 has integral security capabilities that had to be tacked on to IPv4. It is described as a conservative extension of IPv4, not a revolutionary replacement. Applications such as virtual private networks, voice over IP and peer-to-peer networking should all be more powerful and manageable under IPv6.
What makes it special?
IPv6 will not only support a vast increase in the number of internet devices, but will lower the cost of internet-enabling them. It will reduce application complexity and eliminate the need for dynamic address translation.
However, Geoff Huston, senior researcher at Asia-Pacific internet registry Apnic, said, "Existing players currently have strong motivations to defer expenditure decisions because of shareholder pressure. When you add to this the consideration that IPv6 is a step back to a simpler, cheaper network, then this translates to an incremental investment that will reduce their revenue yield per customer."
How difficult is it to master?
Evolutionary or not, IPv6 training is expected to make up a large part of the cost of transition. Existing IPv4 practitioners can learn IPv6 on a four-day course.
What systems does it run on?
Most new IT equipment is supplied IPv6-ready.
What's coming up?
US federal agencies are supposed to implement IPv6 by 2008. The UK government and European Commission have set up task forces to promote it, but without firm dates.
Rates of pay
Junior network engineers with IP skills can earn between £25,000 and £35,000.
IPv6 training is available from major equipment suppliers and their partners. Some free basic tutorials and other resources are available online.