Internet Protocol (IP) version 6

Internet Protocol (IP) version 6 (IPv6 or IPng) is the next generation of IP and has been designed to be an evolutionary step from IP version 4 (IPv4).

While IPv4 has allowed the development of a global Internet, it is not capable of carrying much farther into the future because of two fundamental factors: limited address space and routing complexity. The IPv4 32-bit addresses do not provide enough flexibility for global Internet routing. The deployment of Classless InterDomain Routing (CIDR) has extended the lifetime of IPv4 routing by a number of years, but the effort to better manage the routing will continue. Even if IPv4 routing could be scaled up, the Internet will eventually run out of network numbers.

The Internet Engineering Task Force (IETF) recognized that IPv4 would not be able to support the phenomenal growth of the Internet, so the IETF IPng working group was formed. Of the proposals that were made, Simple Internet Protocol Plus (SIPP) was chosen as an evolutionary step in the development of IP. This was renamed to IPng, and RFC1883 was finalized in December of 1995.

IPv6 extends the maximum number of Internet addresses to handle the ever increasing Internet user population. As an evolutionary change from IPv4, IPv6 has the advantage of allowing the new and the old to coexist on the same network. This coexistence enables an orderly migration from IPv4 (32 bit addressing) to IPv6 (128 bit addressing) on an operational network.

This overview is intended to give the reader a general understanding of the IPng protocol. For detailed information, please see RFCs 2460, 2373, 2465, 1886, 2461, 2462, and 2553.

Security provides security information on the TCP/IP suite of protocols, including IPv6. For details about IP Security, versions 4 and 6, see Internet Protocol security.