NTT Communications Corp. has begun offering a consumer IPv6 (Internet protocol version 6) connection service that runs across any standard Internet access line and costs ¥300 (US$2.50) per month. The service, which was launched in Japan earlier this month, is the first of its kind in the world, according to the carrier.

To use NTT's service customers must install an access program, which is offered for computers running the Japanese version of the Windows XP SP2 operating system. The software maintains an IPv6 tunnel across a standard IPv4 Internet connection -- fixed or wireless broadband or dial-up -- to a server that links onto the IPv6 Internet. The software also manages the PC's IPv4 and IPv6 addresses. Windows Vista, Microsoft Corp.'s upcoming new operating system, will include support built-in.

When a user accesses a resource on the Internet, such as a Web site, the PC looks up the site's IP address from its domain name as usual. If an IPv6 address is available, a connection is established via the IPv6 tunnel. If not, the connection is made across the IPv4 connection as usual. In this way users don't need to manually switch between connections.

NTT provides users with two sets of global IPv6 addresses. One set is in a fixed range and allows users to, for example, assign a fixed address to a home music server so it can be accessed from anywhere on the Internet. The other set is a temporary address range. In both cases users have potentially millions of IP addresses to assign to devices around the home.

The availability of permanent IP addresses is a major enabler for the networked home. Today's temporary IPv4 addresses make it difficult to find devices such as home servers from out on the Internet. A permanent address will mean they can always be found. That's important for a wide range of consumer electronics products.

Sony Corp.'s LocationFree TV is a device that connects to your TV antenna, video recorder and set-top box and can stream programming to clients outside of the home via the Internet. At present the device has to keep in touch with a Sony-run server so it can always be located, but a switch to IPv6 -- both in the connection and device itself -- would mean it's address on the Internet never changes.

At present users will have to keep a PC running at home to handle the interconnection between their gadgets and the wider IPv6 Internet, because support for IPv6 isn't built into most gadgets, but a new range of products and routers with IPv6 support will change that. One IPv6 device already available in Japanese computer stores is a network camera from Matsushita Electric Industrial Co. Ltd. (Panasonic). The device just needs to be plugged into an IPv6 connection and can serve images itself.

The IPv6 consumer service is available now in Japan through NTT's consumer Internet access service, OCN. It costs ¥300 per month for the IPv6 link but users must supply their own Internet connection. Users who are not currently OCN customers and wish to use their existing Internet connection must pay an additional ¥250 per month to become an OCN customer.

More information on NTT's IPv6 service and projects can be found online at http://www.ipv6style.jp .