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IPv4 Addresses in North America: Going, Going, Gone!

Like the monotonous droning sound of jungle drums so has been the repetitive and continual predictions about the exhaustion of world’s supply of public IPv4 address. We have been hearing about the impending scarcity of IPv4 addresses for so long that we don’t hear the calls to action. The recent announcement by The American Registry […]

Like the monotonous droning sound of jungle drums so has been the repetitive and continual predictions about the exhaustion of world’s supply of public IPv4 address. We have been hearing about the impending scarcity of IPv4 addresses for so long that we don’t hear the calls to action. The recent announcement by The American Registry for Internet Numbers (ARIN) that they have reached IPv4 exhaustion has now signaled the alarm. Organizations can no longer ignore what the future of the IPv4 Internet may be like. Instead, they must seize ownership of their own destiny and deploy IPv6.

IPv4 Addresses

When the Internet Protocol (IP) was being developed in the 1970s the number of endpoints was quite small. The working being done at Defense Advanced Research Projects Agency (DARPA) was done with a small set of university research and government systems. The 32-bit addresses used with IPv4 are hierarchically allocated (like phone numbers) and used quad dotted decimal notation for human readability. At the time the Internet Protocol was developed, no one could have possibly predicted the impending popularity of the Internet.

Addressing and routing go hand-in-hand and the inefficiency of allocation of IPv4 addresses eventually led to a worldwide shortage of addresses. The IETF Address Lifetime Expectations (ALE) Working Group anticipated back this trend back in the mid-1990s that this date would come. With the introduction of Classless Interdomain Routing (CIDR) and Network Address Translation (NAT) in the mid-1990s, IPv4 has been on extended life-support for almost two decades. For almost a decade the community has been watching Geoff Huston’s IPv4 Address Report as a guide to anticipate when IPv4 exhaustion would occur.

IANA and the RIRs

The Internet Assigned Number Authority (IANA) depleted their free pool of IPv4 address space on February 3, 2011. On that date, all the available IPv4 addresses had been allocated to the five Regional Internet Registries (RIRs) around the world. Each RIR has had to independently manage their own supply of IPv4 addresses resources. However, each RIR has had a different strategy for their exhaustion stage/phase schedule. Each RIR has had a different policy for how they are effectively managing the allocation of their limited IPv4 resources.


The Asia-Pacific Network Information Centre (APNIC) has had an extremely fast-growing Internet population and took a particularly aggressive stance on IPv4 address allocation and prioritizing IPv6 deployment. Their supply of IPv4 addresses ran out on April 15, 2011. APNIC has been giving guidance to their member organizations for years on IPv4 address exhaustion and has a page on what is happening in the post-exhaustion phase.


The next RIR to run out of IPv4 addresses was Réseaux IP Européens Network Coordination Centre (RIPE NCC). Their supply of public IPv4 addresses passed their final /8 equivalent on September 14, 2012. RIPE NCC’s policies state that their members can make a one-time request for a /22 allocation and no new Provider Independent (PI) allocations will be made.


The Latin America and Caribbean Network Information Centre (LACNIC) was the next RIR to exhaust their supply of IPv4 addresses. This occurred on June 10, 2014 as a result of their growing Internet community. Their member organization continue to grow their Internet access and LACNIC has initiatives around helping their members embark on the IPv6 path.


The American Registry for Internet Numbers (ARIN) is the Regional Internet Registry (RIR) for the U.S., Canada, and Caribbean and North Atlantic islands. North America has had a large Internet-connected population, but as more systems and organizations have connected to the Internet, ARIN has processed numerous requests for public IPv4 addresses.

ARIN entered Phase 4 of their IPv4 Exhaustion plan on April 23, 2014 and has been operating under their Phase 4 policies since then. During Phase 4, any new request for IPv4 address space is reviewed by the IPv4 Review Team queue where they are reviewed in a first-come first-served basis. ARIN has been managing the IPv4 Request Pipeline as their IPv4 stockpile dwindles. The current IPv4 address inventory is listed on ARIN’s IPv4 depletion page. ARIN has an IPv4 Depletion blog where you can find the latest information on this topic.

Now that IPv4 exhaustion has occurred for ARIN members, the rules for future IPv4 allocations will change. ARIN members can make address requests, but ARIN is likely to not have address supply to meet those requests. Applicants will either be given the choice to accept a smaller block than they requested or get their name added to a waiting list. Applicants can also withdraw their request and chose to acquire their IPv4 addresses from another source. This ARIN web page provides information on the waiting list for unmet IPv4 address requests. These guidelines are published in the Number Resource Policy Manual (NRPM) Section 4.1.8.


The African Network Information Centre (AfriNIC) has a growing Internet population too, but they have not reached exhaustion of their IPv4 address supply. As more of their communities come online their usage of their remaining IPv4 addresses are likely to accelerate.

Next Steps

Using both IPv4 and IPv6 in parallel dual-protocol mode gives your organization the best position to be able to communicate with the broadest Internet community. Deploying IPv6 is a long-term strategy, but enterprise organizations must start that process immediately. However, even if organizations aggressively deploy IPv6, they will still experience a short-term IPv4 address shortage. Still, organizations may be forced to purchase/lease public IPv4 addresses and now those IPv4 addresses will only become more expensive.

If you haven’t embarked on the IPv6 path yet, there is no time like the present to define your organization’s IPv6 strategy. Ed Horley, Practice Manager – Cloud Solutions and the Practice Lead – IPv6 at Groupware Technology, and Infoblox IPv6 Center of Excellence member has a great blog with some solid guidance for enterprises on how to get started with IPv6. Following are his first phases of an IPv6 plan.

This post originally appeared on the Infoblox blog at https://community.infoblox.com/blogs/2015/07/01/north-america%E2%80%99s-ipv4-address-shortage

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