Background

TCP and UDP are the protocols on which all Internet applications depend. TCP and UDP, in turn, depend on IP. IP is the glue that joins the world's diverse collection of hosts, LANs and WANs into a single big virtual network. Without IP, the Internet as we know it would not exist.

Every machine that connects to the Internet must have a unique address. The current version if IP, version 4, uses 32-bit addresses. In theory, 32 bits results in many addresses (over 4 billion), but in practice only a fraction of the addresses can be used. The Internet is growing exponentially. In January 1993 there were an estimated 1.3 million machines; by January 1996, the number had reached 9.5 million [Reference]. There is widespread agreement within the Internet community that the Internet will run out of addresses early in the next century. The debate is not if, but when.

IP Version 6

IP Version 6 (IPv6) is the specific protocol chosen by the IETF as the Internet's Next-Generation IP. IPv6 uses 128-bit addresses, to insure sufficient addresses to last well into the 21st Century and beyond.

Given that IP had to change to accomodate bigger addresses, the IPv6 standardization effort also extends and improves on known limitations of IPv4. Specifically, IPv6 has the following advantages:

Status of IPv6

The specifications for the core pieces IPv6 protocols have been issued as Proposed Standards by the IETF, and all major vendors (host and router) are known to be doing IPv6 implementations. Indeed, the UNH Interoperability Lab hosted IPv6 "testathons" in February and June of 1996 for vendors to test out there implementations. Sun, HP, Digital, IBM (AIX), Bay Networks and Ipsilon have participated. Both Sun and Digital have prototype implementations that folks can download from the Internet for testing purposes. More information on implementations can be found here

For More Information

For information on the official current status of IPv6, the various draft documents the WG is developing, pointers to the mailing list (and its archives), etc., visit the IETF's official IPng Working Group page. Another good collection of semi-official material can be found at the playground archive, which is maintained by one of the IPng WG co-chairs.

For background on the issues that lead to the decision to chose IPv6 as the next standard, consult RFC 1752 and its extensive set of references. The book "IPng Internet Protocol Next Generation" (S. Bradner, A. Mankin editors, 1995. (ISBN 0-201-63395-7) contains similar information, but edited and distilled for easier reading.

If you think it's about time you learned something about IPv6, but don't know where to start, there is already at least one book on IPv6 that delves into the technical detail of the protocols: "IPv6 The New Internet Protocol" (Christian Huitema, 188pp., 1995. ISBN 0-13-241936).

If you would rather go straight to the RFCs, I'd suggest starting with the following (in approximate priority order).