IPv6 (Internet Protocol version 6) is the latest revision of the Internet Protocol (IP), the primary communications protocol upon which the entire Internet is built. It is intended to replace the older IPv4, which is still employed for the vast majority of Internet traffic as of 2012. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 running out of addresses.
Each device on the Internet, such as a computer or mobile telephone, must be assigned a number called an IP address, a binary number with a certain number of digits (each presented by one bit), in order to communicate with other devices. With the ever-increasing number of new devices being connected to the Internet, there is a need for more addresses than IPv4 can accommodate. IPv6 uses 128-bit addresses, allowing for 2128, or approximately 3.4×1038 addresses — more than 7.9×1028 times as many as IPv4, which uses 32-bit addresses. IPv4 allows for only 4,294,967,296 unique addresses worldwide (or less than one address per person alive in 2012), but IPv6 allows for around 4.8×1028 addresses per person — a number unlikely ever to run out. However, this means the two protocols are not compatible, complicating the transition to IPv6. IPv6 addresses, as commonly displayed to users, consist of eight groups of four hexadecimal digits separated by colons, for example 2001:0db8:85a3:0042:0000:8a2e:0370:7334.
The deployment of IPv6 is accelerating, with a World IPv6 Launch having taken place on 6 June 2012, in which major internet service providers, especially in countries that had been lagging in IPv6 adoption, deployed IPv6 addresses to portions of their users. Data from Arbor Networks showed a peak of 0.2% of Internet traffic on IPv6 during the launch.
IPv6 is designed to solve many of the problems of IPv4, including mobility, auto-configuration, and overall extensibility. IPv6 expands the address space on the Internet and supports a nearly unlimited number of devices that can be directly connected to the Internet.
Microsoft is committed to expanding the worldwide capabilities of the Internet through IPv6 and enabling a variety of new and exciting scenarios. Microsoft and other major technology companies have been working behind the scenes for years to deliver a smooth transition from IPv4 to IPv6—in effect an upgrade of the entire Internet—and we continue to lead in the development of this new standard.
IPv6 is the replacement for IP version 4 (IPv4), the Internet layer protocol of the TCP/IP protocol stack in prevalent use around the world today. IPv6 solves many of the problems and shortcomings of IPv4, providing an Internet layer protocol that can scale to the future needs of devices that will connect to the Internet. The most prominent feature of IPv6 is the use of 128-bit addresses (rather than 32-bit addresses), which allows for 3.4 × 1038 possible addresses, more than enough to handle today's needs and those of the foreseeable future.
IPv6 is not backward compatible with IPv4. An IPv6-only node cannot communicate with an IPv4-only node. Therefore, a careful transition must occur from an IPv4-only network to a network that supports both IPv4 and native IPv6. As more nodes and applications on the network become IPv6-enabled, the majority of traffic on your network shifts over time from mostly IPv4 to mostly IPv6. This is the current goal of an IPv6 transition strategy. Due to the prevalence of nodes, devices, applications, and network management systems that support only IPv4 now, with few exceptions, the goal of your IPv6 transition strategy is to migrate from an IPv4-only network to a network that supports both IPv4 and IPv6 traffic, not to migrate to an IPv6-only network.
Today's practical applications of IPv6 include the following:
An addressing scheme that scales to the largest of networks
Current public IPv4 address space is limited and usually reserved for Internet-facing hosts. Even when you use the IPv4 private address space on your intranet, IPv4-only intranets can only scale so far. With IPv6, public address space is very easy to obtain and private address space, using Unique Local Address (ULA) prefixes, can apply to each site of your organization. The combination of public address space and ULA prefixes allow you to scale your intranet to an enormous size.
Ability to use IPv6-only services and applications
The latest versions of Windows have features that are either IPv6-only or work best in an IPv6-