IPv6, or Internet Protocol version 6, is a new format governing communication between computers over the Internet. Over the next several years it will probably enter widespread use as we run out of IP addresses under the current regime, IPv4 (Internet Protocol version 4). The new standard exponentially increases the total number of computers which can potentially connect to the Internet, at the expense of addresses which except in specific circumstances will be nearly impossible to remember, as well as continuing uncertainty over how to make a smooth transition.
- About the IPv4 Address Crisis and IPv6 -
On the Internet, every computer communicates according to certain pre-established rules. For the moment, the most pressing of these is that each computer is given a unique number address consisting of four numbers between 0 and 255 (for example, 65.200.0.255), which functions in roughly the same way as a telephone number. This system of allocating numbers is known as IPv4, and is the one currently used to make the World Wide Web possible. Unfortunately, simple mathematics shows that this system only allows about four billion computers to connect to the Internet. After that, the system runs out of unique numbers to create IP addresses. As designed, the Internet cannot function with multiple computers sharing the same number.
This was not a serious problem when the system was designed during the 1970s and 1980s - indeed, at a time when only a very small number of technical specialists were using the Internet, and computers were very expensive, it was inconceivable that four billion computers would ever exist at the same time, let alone be connected to the Internet. However, the central agency which controls IP addresses, the Internet Assigned Numbers Authority, only has a small number of blocks of numbers left to allocate. After these run out, probably some time next year, it will still be some while yet before they are all assigned to end users, but this will occur, inevitably.
The solution is a new set of rules for assigning numbers, called IPv6. Instead of four billion addresses, IPv6 allows for about 340 undecillion IP addresses: that is, the number 34 followed by 37 zeroes. The new numbers are written in hexadecimal form in groups of four digits, such as 2001:0DB8:AC10:FE01:0000:0000:1000:0000. Unless each person alive today somehow invests in several trillion computers each, space in the new IPv6 system will be plentiful and cheap for an extremely long time to come.
- Advantages of IPv6 -
The chief advantage of IPv6, then, is that it creates enough numbers not only to solve the pending IPv4 address crisis, but also to prevent any future crisis. In the computer industry, predictions that limit the future tend to be proved wrong embarrassingly quickly, beginning with the apocryphal quote from an IBM executive in the 1940s who claimed that America would probably never build more than five computers. Nevertheless, given the vast difference in scale involved, it seems impossible that there will be a shortage of IP addresses again once the IPv6 system is fully implemented.
Other than the addresses, IPv6 is mostly an incremental rather than revolutionary adjustment to the existing IPv4 system. However, for network technicians and other specialists, a number of other features do provide some advantages. The vast amount of space available allows for the creation of more useful subnets for internal use by corporations and other organizations. The IPv6 specification also mandates multicasting capability (so that computers can send data to multiple recipients simultaneously) as well as some new security provisions.
- Disadvantages of IPv6 -
While, on the whole, IPv6 should be a beneficial upgrade to the current Internet, there are some noticeable disadvantages. In particular, the four-number IP addresses of today are relatively easy to remember, although few non-specialists have any need to. In the future, under IPv6, this will become increasingly impossible to do given the size of the address (see above).
In addition, and more seriously, there still seems to be no clear plan for how the transition from IPv4 to IPv6 will actually occur. Recent versions of all major operating systems, including Microsoft Windows, Apple's Mac OS X, and Linux, do incorporate support for IPv6. It is less clear how Internet service providers will make the transition. The degree of backwards-compatibility between the two is limited, and if we continue to run through the limited unallocated addresses available as quickly as we currently are, the time available for a slow, orderly transition is limited. Complete chaos is unlikely, but a painful transition involving a series of tricky and occasionally buggy workarounds is quite conceivable. Ideally, most of this will occur behind the scenes, so that the average consumer does not realize that a transition is occurring. Obviously, the more complicated and flawed the process, the more inconveniences will be caused to end users.