【正文】 tment39。s Internet uses IPv4, which is now nearly twenty 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 added to the Internet. IPv6 fixes a number of problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as routing and network auto configuration. IPv6 is expected to gradually replace IPv4, with the two coexisting for a number of years during a transition period. Some introductory information about the protocol can be found in our IPv6 FAQ. For those interested in the technical details, we have a list of IPv6 related specifications. Internet Protocol Version 6 is abbreviated to IPv6 (where the 6 refers to it being assigned version number 6). The previous version of the Internet Protocol is version 4 (referred to as IPv4). IPv6 is a new version of IP which is designed to be an evolutionary step from IPv4. It is a natural increment to IPv4. It can be installed as a normal software upgrade in Internet devices and is interoperable with the current IPv4. Its deployment strategy is designed to not have any flag days or other dependencies. IPv6 is designed to run well on high performance networks (. Gigabit Ethernet, OC12, ATM, etc.) and at the same time still be efficient for low bandwidth networks (. wireless). In addition, it provides a platform for new Internet functionality that will be required in the near future. IPv6 includes a transition mechanism which is designed to allow users to adopt and deploy IPv6 in a highly diffuse fashion and to provide direct interoperability between IPv4 and IPv6 hosts. The transition to a new version of the Internet Protocol must be incremental, with few or no critical interdependencies, if it is to succeed. The IPv6 transition allows the users to upgrade their hosts to IPv6, and the network operators to deploy IPv6 in routers, with very little coordination between the two.Where can I get an IPv6 implementation for my system?There is software available for most operating systems in mon use today. Find your favorite OS on our list of IPv6 implementations. We also have a collection of how to install documents for various systems. What applications run over IPv6 today?Many mon Internet applications already work with IPv6, and more are being ported. See our list of IPv6 enabled applications. Benefits of IPv6One of the clearest benefits of IPv6 is the increased address space.IPv4 was defined before it was understood just how explosive the Internet would be. Consequently available addresses for IPv4 hosts are running out. Many analysts predict hundreds of millions of mobile phones will be in use and require network connectivity. There will be literally trillions of network devices with in a decade.IPv6 also benefits from the experience of the protocol developers. Many new ideas and features that have been addedon to the IPv4 specification can now be a fundamental part of the new protocol. This certainly helps the various features work as intended with each other.The specification also enables an lPv6 host to be automatically configured by the upstream router. As the host boots up it will solicit a router for its address prefix and other information that is usually manually configured. This scheme also makes it much easier to renumber the machines, for example if the site changes service provider. In the case of multihomed sites there will be multiple addresses per system.To some, the most important feature is restoring the endtoend nature of the Internet. This ideal has been eroded by private networks behind Network Address Translator (NAT) boxes .Improved Security is possible with endtoend connections and in fact, some versi