IPv6, or International Protocol version 6, is the planned successor to the current IPv4 system of allocating IP addresses to computers connected to the Internet around the world. Briefly, all computers connecting to the Internet must possess a unique identification number, known as an IP address and essentially analogous to a telephone number. However, the current IPv4 system of IP numbers possesses only about 4 billion addresses, and most of these have now been claimed by service providers around the world. IPv6 is a new system which introduces much larger address numbers, so that many more devices will be able to connect to the Internet at the same time.
- The Coming IPv4 Crisis -
All computers on the Internet must have a unique number so that they can send and receive information to, at least potentially, any other computer on the Internet. For years, these numbers were designated through the fourth version of the Internet protocol (IPv4), which designated computers according to four numbers between 0 and 255 (for instance, 62.79.86.255). Some ranges within this were reserved for a variety of purposes, so that in practice slightly less than the theoretical maximum of about 4.3 billion unique IP addresses could be in use at any given time.
Four billion unique addresses, however, is not enough to cope with the rising demand for new technology. The central address agency, the Internet Assigned Numbers Authority (IANA), parcels out groups of 16.8 million addresses at a time through the Regional Internet Registries in North America (ARIN0, Europe (RIPE NCC), Asia and Australia (APNIC), and Africa (AfriNIC). There are 221 such blocks of addresses on the Internet, of which 205 have already been given out. Moreover, IANA has already agreed that when it is down to the last five, it will give one to each of the regional registries. This means there are sixteen blocks of unused space left, and we are continuing to allocate them at a little over one block per month. Once all IPv4 addresses have been sold, probably sometime next year, it does not actually mean they are in use yet - but it does mean that IP addresses will stop being a routine technical detail and start becoming prized, expensive real estate.
- About IPv6 -
The basic protocols at the heart of the Internet have more than proven their worth - indeed, the only real problem (but it is not at all a small problem) is that IPv4 is simply running out of numbers. IPv6 makes two basic changes to allow much larger numbers. First, where IPv4 combined four "digits" of between 0 and 256, an IPv6 address consists of eight blocks of four digits. Each digit is hexadecimal (base-16 rather than base-10). Thus, the total number of unique useable addresses made possible under IPv6 is about 340 undecillion - that is, the number 34 followed by thirty-six zeroes. Today's entire Internet can be squeezed into a small and insignificant subnet on the new IPv6 system.
The new numbering system, then, more then solves the space crisis facing the IPv4 system. At the same time, the designers of IPv6 had more in mind when they designed it then simply providing for a very large number of IP addresses. This should be obvious: even if every person on Earth today decided to invest in buying several trillion computers each, the result could still be easily absorbed by the IPv6 system. Instead, now that space will become relatively free and cheap again, hopefully networks can be more efficiently reorganized.
In addition to the above, there are some new alterations to how Internet protocols work as part of IPv6, although for the most part these are incremental changes to the IPv4 system which will interest network technicians but have little impact on everyday users. These additions include mandatory multicast capability (so that a single packet can be sent to several computers at once), and new security features.
- History of IPv6 -
The Internet was originally intended as a collaborative experiment between the military and American universities - and then, when it expanded to the public, was seen largely as a space for programmers and geeks. By the early 1990s, when it was apparent that this woefully underestimated the Internet's potential, networking engineers were also becoming aware that the existing Internet Protocol (IP) address system would be woefully unprepared for future expansion. Four billion addresses sounded impressive when large institutions owned a few computers each - but not billions of people were looking forward to one day having a computer of their own, and then some.
In 1994, the Internet Engineering Task Force (IETF) set up several groups to develop what it then referred to as IPng, the Next Generation Internet Protocol. Over the coming years, this became the framework for today's IPv6. Currently, all major operating systems, including the latest versions of Microsoft Windows and Apple's Mac OS X, support IPv6 Internet connections. However, for the most part we continue to access the Internet through IPv4 addresses, and it remains to be seen how smoothly Internet service providers will be able to make the transition as we run through the last of the remaining free IPv4 space in the next few years.