<networking, protocol> (IPv6, IPng, IP next generation) The most viable candidate to replace the current Internet Protocol. The primary purpose of IPv6 is to solve the problem of the shortage of IP addresses.
The following features have been purposed: 16-byte addresses instead of the current four bytes; embedded encryption - a 32-bit Security Association ID (SAID) plus a variable length initialisation vector in packet headers; user authentication (a 32-bit SAID plus variable length authentication data in headers); autoconfiguration (currently partly handled by Dynamic Host Configuration Protocol); support for delay-sensitive traffic - a 24 bit flow ID field in headers to denote voice or video, etc.
One possible solution is based on the TUBA protocol (RFC 1347, 1526, 1561) which is itself based on the OSI Connectionless Network Protocol (CNLP). Another is TP/IX (RFC 1475) which changes TCP and UDP headers to give a 64-bit IP address, a 32-bit port number, and a 64-bit sequence number.
RFC 1550 is a white paper on IPng.
["Doubts About IPng could create TCP/IP chaos", Johna Till Johnson, Data Communications, Nov 1994].