Owen DeLong, IPv6 evangelist and director of professional services at Hurricane Electric (http://www.he.net/), says:

In February of 2011, the IANA distributed the last five available blocks of IPv4 addresses – one block to each of the five Regional Internet Registries (RIRs). APNIC, the RIR for the Asia/Pacific Region, is down to its last /8 block of IPv4 addresses and has implemented allocation policies that limit each applicant to a single /22 subnet. The other four RIRs (AfriNIC, ARIN, LACNIC, and RIPE) are forecast to distribute the last of their remaining address blocks in the latter half of 2011. Inarguably, the exhaustion of the IPv4 address space is upon us, yet many telecommunication companies are postponing the transition to IPv6 at their peril.

Organizational inertia is the single biggest challenge to the embrace of IPv6 in many large telecom companies. Fear, uncertainty and doubt are often factors; indeed, it is often difficult to devote resources to immediate problems, let alone to a problem whose costs will accrue at an unknown time. Another factor is the incorrect assessment (stemming from technological naiveté) that stopgap measures – like additional layers of NAT – can suffice indefinitely.

In some cases, the dependence upon network infrastructure containing an incomplete IPv6 feature set justifies delay. Examples of this include the lack of DNS server information in SLAAC (partially solved now, but not widely deployed yet) and the inability of DHCPv6 to provide gateway or routing information. In other limited cases, vendors have failed either to implement workable IPv6 products or to achieve IPv4 feature parity. Although it is certainly true that early adoption creates extra challenges like these, we are long past the “early” stage of IPv6 adoption; the dedication of intellectual resources to such challenges is a necessary condition of IPv6 mastery. It is better to gain the understanding now, before IPv6 becomes a customer-critical service (probably by the end of this year) and IPv6’s advantages simply become requirements.

Beyond IPv6’s enormous address space, IPv6 boasts a number of benefits that make the transition worth the effort today. IPv6 features improved routing efficiency and reduced router processing – thanks to a simpler, more consistent header. IPv6 also provides cleaner and simpler security through IPsec, better aggregation of networks, simplified planning for network growth, support for true peer-to-peer connectivity, and elimination of complex layers of indirection (like NAT).

Thankfully, many telecom companies are not dragging their feet. Content Delivery Networks (like Limelight and Akamai) plan to become fully IPv6 compliant before 2011 ends. The infrastructure behind the global Internet has become dual-stacked over the last ten years. The root name servers (fundamental to how we convert names like example.com into address numbers) have been IPv6-enabled for many years. Top Level Domains (TLDs) like .com, .net and .us are serviced by domain name servers that are dual-stacked. Presently 256 out of 306 TLDs are enabled for IPv6. In fact, a recent Infonetics report suggests that 83% of service providers are either offering IPv6 services or plan to by next year.

To paraphrase an ancient text, the writing is on the wall: The days of IPv4 are numbered, and the justifications for delay have been found wanting.