| Toru Takesue | Carrier Solution Dept., Network Solution Div., |
| Shiro Tanabe, Ph.D. | Network Architecture Dept., IP Network Research Center., Central Research Lab., |
| Shinichi Iwaki | Carrier Business Promotion Center, Network Solution Div., |
Based on IPv4 (Internet protocol version 4), which was standardized in the 1980s, the Internet has developed rapidly into an infrastructure indispensable to today's society. IP (Internet protocol) networks, such as the Internet, continue to be enhanced in terms of both speed and functionality. Progress in speed is particularly prominent in access networks, which now support broadband communications in copper, wireless, and optical fiber transmission mediums. IP networks must provide several functions including provisions for guaranteed QoS (quality of service), mobility, collaboration between servers, and high-value-added services. However, an IPv4-based Internet has limitations in terms of scalability, QoS guarantee, and manageability because IPv4 was originally designed as a network interconnecting researchers and, as such, had not anticipated its current role of providing a social infrastructure. IPv6 is not a mere extension of network address domains over IPv4 but is a key technology to overcome the above-mentioned limitations.
IPv6 network, the Internet, quality of service, mobility, network address, broadband
