The world's IPv4 addresses are officially exhausted!

The long-feared exhaustion of global IPv4 addresses has finally arrived today - all 4.3 billion IPv4 addresses have been allocated, which means there are no more IPv4 addresses to be allocated to ISPs and other large network infrastructure providers.

This process had been foreseen since the 1980s, and the top-level addresses were actually exhausted in 2012. At that time, all IPv4 address space had been allocated to five regional Internet registries, the African Network Information Center (AFRINIC) for Africa, the North American Network Information Center (ARIN) for Antarctica, Canada, parts of the Caribbean, and the United States, the Asia-Pacific Network Information Center (APNIC) for East Asia, Oceania, South Asia, and Southeast Asia, the Latin American Network Information Center (LACNIC) for much of the Caribbean and all of Latin America, and the European Network Information Center (RIPE NCC) for Europe, Central Asia, Russia, and West Asia.

Those Regional Internet Registries quickly started running out of space. On April 15, 2011, Asia Pacific (APNIC) allocated its last IPv4 block, on September 14, 2012, for Europe, the Middle East and Central Asia (RIPE NCC), on June 10, 2014, for Latin America and the Caribbean (LACNIC), on September 24, 2015 for North America, and today, the European RIPE (World Internet Organization) NCC has finally run out of storage.

The news was announced in an email (published by Nikolas Pediaditis) which reads:

Dear Colleagues,

Today, at 15:35 UTC+1 on November 25, 2019, we made our final /22 IPv4 allocation from the last remaining addresses in the available pool. We have now run out of IPv4 addresses.

For network operators, our announcement should come as no surprise – the RIPE community has long anticipated and planned for IPv4 exhaustion. In fact, it is thanks to the community’s responsible stewardship of these resources that we have been able to deliver /22 allocations to thousands of new networks in our service area since reaching our last /8 in 2012.

In theory, IPv4 address exhaustion should mean that no new IPv4 devices can be added to the Internet, but in practice, a number of factors work to mitigate.

The first is that ISPs can reuse and reclaim unused IPv4 addresses. The second is that the same IP address can be used privately behind an ISP router due to NAT (Network Address Translation). And of course, the last is the transition to IPv6, which should be well-ordered by now, allowing direct peer-to-peer connections over the Internet with its massive 3.4×10^38 address space.