Mark A. Miller, P.E., President, DigiNet Corporation

Remember that film classic The Wizard of Oz? The Wizard had built up quite a reputation for himself until Toto the dog pulled back the curtain that he was hiding behind, revealing a panel with only dials and levers that generated a lot of smoke, but little else.

In a similar way, the new IPv6 protocol has gathered a great deal of industry interest because of its enhanced addressing structure, solving the shortage of IPv4 addresses in a very dramatic way. (It has been estimated that there is an IPv6 address for every proton on earth, so we are not likely to run out any time soon!) But if we pull back the curtain, what other IPv6 capabilities are back there? To answer that question, we need to go back to one of the earlier design documents for IPv6, Request for Comments (RFC) 1752, published by the Internet Engineering Task Force (IEFT) in January 1995, and titled The Recommendation for the IP Next Generation Protocol (see http://www.rfc-editor.org/rfc/rfc1752.txt).

As a brief historical note, in 1990 the IETF recognized that the address exhaustion would become an issue in the future, and began looking for a successor to IPv4. The organization solicited input from across the voice and data communications industries, and received responses from a variety of sources, including cable television, electric power, and cellular telephone interests. During the next few years, several different proposed protocols were developed, with interesting names that included CATNIP (Common Architecture for the Internet), SIPP (Simple Internet Protocol Plus), and TUBA (TCP and UDP with Bigger Addresses). All three of the proposals were reviewed, with none providing a solution that was completely satisfying to the evaluating committee. Nevertheless, individual elements of the three proposals were found to have merit, and a resulting “best of breed” features list was developed. These key IPv6 features included:

• Expanded addressing and routing capabilities: increasing the IP address field size from 32 to 128 bits, plus providing for more levels of addressing hierarchy and auto-configuration of addresses.
• Simplified header format: eliminating some of the fields in the IPv4 header that were seldom used (recall that IPv4 was originally designed to meet U.S. Government communications requirements, not all of which were applicable to enterprise applications), thus reducing the packet processing overhead for devices (such as routers) that needed to examine the header in every IPv4 packet. This simplification yielded an IPv6 header that is only twice the size of the IPv4 header, even though the IPv6 addresses are four times as large.
• Support for Headers Extensions and Options: some IPv6 packets may require special handling, such as specifying a particular path from the source to the destination (for perhaps load balancing or security purposes). Since not all packets may require this special handling, the streamlined IPv6 packet header is extended only when necessary, to include this additional packet handling information. By making these extensions optional, the additional processing overhead does not impact every packet, thus benefitting the overall transmission system as a whole.
• Support for authentication and privacy: including mechanisms to ensure the confidentiality of the packet contents, which could be of great benefit to the transport of financial (and many other) types of transactions that require non-disclosure.
• Support for autoconfiguration: the “plug and play” mechanism, which allows an IPv6 device to be added to a network with little or no human involvement.
• Support for source routes: allowing the source of the packet (i.e. a host computer) to determine the path that a specific packet, or flows of packets, will take through the associated internetwork.
• Simple and flexible transition from IPv4: the capabilities to move from the existing IPv4 that allow for incremental upgrades, incremental deployments, the continuing use of existing IPv4 addresses, and low startup costs. By simplifying these transitions processes, barriers to making that transition are thus removed.
• Quality of service capabilities: the ability to label traffic flows that require special packet handling, such as would be needed for the transport of real time information, such as voice or video.

So you see, there is quite a bit more behind the IPv6 curtain than just the ability to generate a lot of smoke; and as enterprise IPv6 deployments proceed, we will undoubtedly hear more about these interesting capabilities. (My personal prediction is that the built-in security enhancements are going to steal the show, but we can save that for another discussion). Our next article will examine a more current event that should produce more than just a lot of smoke: World IPv6 Day coming to a network near you in June.

Author’s Biography

Mark A. Miller, P.E. is President of DigiNet Corporation®, a Denver-based consulting engineering firm. He is the author of many books on networking technologies, including the Internet Technologies Handbook, published by John Wiley & Sons.