The Next Version of the Internet Protocol - IPv6 - Page 4

 By Pete Loshin
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Part 4: Migrating to IPv6

Migrating to IPv6

Software upgrades, particularly operating system upgrades, can have a huge impact on organizations. Remember the transition from Windows 3.x to Windows 95? In addition to the raw cost of the OS upgrade, system hardware had to be upgraded or systems discarded because they lacked the RAM, CPU, or hard drive resources to run the new OS. Migration to IPv6 is likely to produce less intense pain and has the potential for being less expensive. For one thing, the transition will be gradual. Brian Carpenter, Internet Architecture Board (IAB) chair and Program Director of Internet Standards and Technology for IBM, explains: "We never expected the transition process to take less than 15 years, counting from around 1994."

Another active member of the IPng working group and senior member of technical staff at Compaq's UNIX Internet Engineering Group, Jim Bound, urges not to "view IPv6 as a migration or transition for the majority of organizations, but rather the 'interoperation' of IPv6 with IPv4 for some time." Bound continues, "It's important to realize that IPv6 is an evolution from IPv4, not a revolution to a [totally] new Internet Protocol."

By design, moving to support IPv6 will mean moving to a multiprotocol Internet rather than a full-blown protocol cutover or flag-day conversion. No one expects IPv4 to go away, ever. Which means that the big question will not be whether or not to upgrade to IPv6, but rather when, how, where, and how much to transition to support for IPv6. Supporting IPv6 is going to be both simpler and more complex than any other networking decision you'll make.

IPv6 interoperability with IPv4 is supported in three ways: tunnels, translators, and dual-stacks. As Bound explained, these are all works in progress: "Right now, to build any products on these technologies is premature." He continued, "multiple tools will be defined...a user will have a range of tools to use just like a carpenter, mason, or landscaper does in their tasks." According to Bound, no single mechanism is "better" than the others; he can "see a case where all three are used in one organization eventually."

There is no single road to IPv6 support. Some individual networks will be upgraded en masse, creating reservoirs of IPv6 support surrounded by oceans of IPv4. Individuals within the IPv6 networks can be IPv6-only, but IPv4/IPv6 gateways are necessary at their borders for these networks to interoperate with IPv4 networks. And different IPv6 networks can communicate with each other through the IPv4 Internet by setting up IPv6/IPv4 tunnels.

Other organizations will migrate host by host, with dual-protocol IPv4/IPv6 nodes scattered throughout the existing IPv4 network like raisins in a loaf of raisin bread. These nodes will be able to interoperate with each in native IPv6, or with IPv6 nodes outside the network by tunneling IPv6 inside IPv4 packets.

This article was originally published on Oct 11, 1999
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