Rapid IPv6 momentum and sunsetting IPv4

Bill Cerveny/Arbor Networks
07 Sep 2012

The next-generation Internet Protocol, IPv6, has experienced more growth in the last two years than in any other period in its 18-year existence . While there are many challenges ahead in the deployment of IPv6, IPv6 is a certain, although eventual, replacement for the currently dominant IP protocol, IPv4.

As deployment of IPv6 gains momentum worldwide, the Internet Engineering Task Force (IETF) has begun examining how to accelerate IPv6 as the dominant IP version and how to handle the ramping down of IPv4.

The IETF has made an important step forward by stating that IPv6 support is no longer optional in an IP- or internet-capable device. As envisioned by IETF RFC 6540, “IPv6 Support Required for IP Capable Nodes,” all devices that claim to be IP-capable or Internet-capable must support IPv6 and may optionally support IPv4.

In defining its guidance, RFC 6540 states that best practices should be:

• New IP implementations must support IPv6.
• Updates to current IP implementations should support IPv6.
• IPv6 support must be equivalent or better in quality and functionality when compared to IPv4 support in a new or updated IP implementation.
• New and updated IP networking implementations should support IPv4 and IPv6 coexistence (dual-stack), but must not require IPv4 for proper and complete function.
• Implementers are encouraged to update existing hardware and software to enable IPv6 wherever technically feasible.

It is hoped that this RFC sends a strong message to the internet community that IPv4 support should now be considered optional and IPv6 support mandatory.

From a number of perspectives, it is easier to maintain a network based on a single version of the Internet Protocol. Running a network with only one IP version should be the end-goal of any IPv6 deployment effort. Although there are many similarities in how IPv4 and IPv6 are designed, in many cases the two Internet Protocol versions operate as “ships in the night.” That said, there are some situations where duplicity of efforts can be mitigated. For example, an IPv6 addressing plan could leverage an existing IPv4 address plan.

Infrastructure for the two IP versions must be mostly managed separately. Addressing for IPv4 must be managed separately than addressing for IPv6. Routing must generally be handled and managed separately for IPv4 and IPv6, even if the same team manages both IP versions and the routing occurs across the same physical network links.

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