Five Japanese and U.S. high-tech firms have developed new Internet connection software compatible with IPv6, the next-generation Internet protocol, a spokesman for one of the five said Friday.

The new router software was developed independently by three Japanese firms -- Hitachi Ltd., Fujitsu Ltd. and NEC Corp. -- and two U.S. firms -- Cisco Systems Inc. and Juniper Networks Inc. -- in cooperation with the Telecommunications Advancement Organization of Japan, an affiliate of the telecom ministry, the Fujitsu spokesman said.

The five firms participated in TAO's project to test and analyze connectivity for new IPv6-compatible router software, and recently succeeded in a connectivity test, he said.

The Internet today mostly uses IPv4, which 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 Net.

Under IPv6, the number of Internet addresses will become virtually limitless, enabling a vast variety of machines, including TVs, refrigerators and other home appliances, to be connected to the Internet. IPv6 is expected to gradually replace IPv4, with the two coexisting for a number of years during a transition period.