During 2011, the long-anticipated and long-dreaded IPv4 address exhaustion finally came about. Of course, operators and service providers have been preparing for years, and are largely educated about what’s involved for migrating from IPv4 to IPv6. That doesn’t they are ready.

Alcatel-Lucent (News - Alert) noted in a recent white paper, IPv6 Transition in Fixed and Mobile Environments, that, “Although IPv6 has been around for some time, very few service providers have actually introduced IPv6 in residential broadband networks.”  The white paper also states that, “Studies indicate that less than 1% of the top 1000 websites support IPv6, and certain applications on the end devices do not support IPv6 connectivity at all.”

The transition is a challenging one because IPv6 is technically incompatible with IPv4, so providers are dealing with a whole new set of concepts for converged IP broadband network operation—while keeping existing systems running. In fact, one of the greatest challenges with the move to IPv6 is how to continue to support IPv4 services in residential broadband environments at the same time as service providers migrate to a mixed IPv4 and IPv6 operational model. In other words, the IPv6 transition is forcing a network evolution.

The issues related to IPv6 are multi-dimensional, and mostly involve elements over which service providers have no control. Many of these elements have to do with network design factors selected for IPv6 introduction. What makes it so complicated is that cable, telecom and mobile service providers may be choosing different, potentially incompatible, elements for rolling out IPv6.

These elements include applications, end devices, access nodes, CPE, IP nodes and BNG/BRAS. For service providers, challenges related to these elements fall into four main categories

• IPv6 in combination with PPPoX in Telco environments
• IPv6 in combination with IPoE in Telco environments
• IPv6 and DOCSIS 3.0 in cable environments
• IPv6 in mobile environments based on R7 or R8 3GPP

In the white paper, Alcatel-Lucent explores these challenges through several IPv6 transition scenarios: IPv6 single stack, IPv4/IPv6 dual-stack deployment options, Tunneling IPv6 over IPv4 using 6RD (anycast), dual stack throughout the network, and partial dual-stack deployment in combination with IPv6-only.

Because there are so many options available, there’s no single answer about the best way to transition from IPv4 to IPv6.

“There are many options in deploying IPv6 and dealing with IPv4 exhaustion,” Alcatel-Lucent noted. “The implications for each will vary based on the network design chosen for introducing IPv6.”

Success, therefore, depends on developing multiple scenarios to support a mixed operational model, and a solid understanding of implications for each scenario.