The American Registry for Internet Numbers (ARIN) has just sent out an alert that its share of the unique URL addresses for the Internet Protocol, Version 4 (IPv4) is running out. Since only a few of four billion or so unique URL addresses possible with IPv4 are left, ARIN has announced that there’s not enough in its stock to satisfy an entire order. So it has activated a stricter procedure by which to assign the few remaining IPv4 addresses.
Specifically, in its just announced policy for unmet requests, when an organization qualifies for a block size that no longer remains in the ARIN IPv4 inventory, they'll be given the option to either accept a smaller block that is available to fully satisfy their request, or to be placed on the waiting list for unmet requests.
“The number of days remaining before depletion are dwindling,” writes ARIN's chief information officer Richard Jimmerson in a blog post just before July 4. “It is very likely that we are already processing a request that we will be unable to fulfill.”
An article in the Washington Post on the ARIN announcement seems to imply that major changes are imminent, but that we are not to worry because IPv6 is available to save us and give us all the URL addresses we need. Only the second part of that is true. Except for many mobile smartphone and tablet users whose wireless service providers are just now making the shift, the transition to IPv6 will take years and even decades. Many existing Internet Service Providers with IPv4 will be around for a long time. Indeed, there is already a growing market for buying used and highly desirable IPv4 addresses.
IPv6 with its 340 trillion trillion trillion possible unique combinations has been sitting in the wings as a replacement for IPv4 since about 2000. But few if any large organizations with the bankroll to establish a presence on the Internet have felt it was economically viable to invest in it until recently. It was not until three to four years ago that major Internet and Web entities under the umbrella of the Internet Society finally started making the transition. Many of those most active in making the shift are in mobile smartphone markets, including AT&T, Google, T-Mobile, and Verizon. Most of them are still only half-way through their deployment and testing on IPv6. And where available, it is being offered only as an optional alternative to IPv4.
Even with the number of its remaining unique addresses drying up, IPv4 still accounts for 93 percent of worldwide Internet traffic. According to a continuously updated chart maintained by Google, as of July 3, 2015, the percentage of users worldwide who access Google via ISPs with IPv6 is currently about seven percent. Google's per country adoption charts indicate that in the United States just slightly over 20 percent of the users who come to Google do so via IPv6 connections.
The reason there is not a rush on IPv6 is simple: economics. Most local, regional, and in some cases national Internet Service Providers are not able or are unwilling to pay the expense of transitioning from their existing base of IPv4-based routers, switches, and servers, except on a slow and years-long incremental basis. In the United States, only the largest of ISPs have committed to the transition, including Charter Communications, Comcast, Global Crossing, Hurricane Electric, Liberty Global, and Time-Warner Cable. IPv6 will slowly eat away at the continued IPv4 dominance, due mostly to new network providers and companies with no investment in existing IPv4.
But most second and third tier regional, statewide, and local ISPs who have major investments in IPv4 are not rushing to make the shift. Engineers and technicians at the several regional ISPs I have dealt with directly over the last decade or so point out that there is no compelling end-use application that cannot be done with existing IPv4. Since about 2000, through the use of such traditional techniques as the use of several levels of subdomains, dynamic rather than static network address translation (NAT), destination and stateful NAT, NAT loopbacks, port address translation, and Internet connection sharing, they have been able to keep up with demands, not only for more bandwidth, but more features and flexibility.