IPv4 address exhaustion

The anticipated shortage has been the driving factor in creating and adopting several new technologies, including network address translation (NAT), Classless Inter-Domain Routing (CIDR) in 1993, and IPv6 in 1998.

[3][4][5][6] All RIRs have exhausted their address pools, except those reserved for IPv6 transition; this occurred on 15 April 2011 for the Asia-Pacific (APNIC),[7][8][9] on 10 June 2014 for Latin America and the Caribbean (LACNIC),[10] on 24 September 2015 for North America (ARIN),[11] on 21 April 2017 for Africa (AfriNIC),[12] and on 25 November 2019 for Europe, Middle East and Central Asia (RIPE NCC).

While the primary reason for IPv4 address exhaustion is insufficient capacity in the design of the original Internet infrastructure, several additional driving factors have aggravated the shortcomings.

Efforts to delay address space exhaustion started with the recognition of the problem in the early 1990s, and the introduction of a number of stop-gap refinements to make the existing structure operate more efficiently, such as CIDR methods and strict usage-based allocation policies.

The Internet Engineering Task Force (IETF) created the Routing and Addressing Group (ROAD) in November 1991 to respond to the scalability problem caused by the classful network allocation system in place at the time.

[21] Although as of 2008[update] the predicted depletion was already approaching its final stages, most providers of Internet services and software vendors were just beginning IPv6 deployment at that time.

[22] Other mitigation efforts and technologies include: On 31 January 2011, the last two unreserved IANA /8 address blocks were allocated to APNIC according to RIR request procedures.

As a consequence of this exhaustion, end-to-end connectivity as required by specific applications will not be universally available on the Internet until IPv6 is fully implemented.

APNIC was the first RIR to restrict allocations to 1024 addresses for each member, as its pool reached critical levels of one /8 block on 14 April 2011.

[7][40][41][42][43][44] The APNIC RIR is responsible for address allocation in the area of fastest Internet expansion, including the emerging markets of China and India.

RIPE NCC, the regional Internet registry for Europe, was the second RIR to deplete its address pool on 14 September 2012.

[45] On 10 June 2014, LACNIC, the regional Internet registry for Latin America and the Caribbean, was the third RIR to deplete its address pool.

[37] On 31 March 2017, AFRINIC became the last regional Internet registry to run down to its last /8 block of IPv4 addresses (102/8), thus triggering the first phase of its IPv4 exhaustion policy.

[51] "On 13 January 2020, AFRINIC approved an IPv4 prefix that resulted in no more than a /11 of non-reserved space to be available in the Final /8," which triggered its IPv4 Exhaustion Phase 2.

These addresses will be allocated to our members (LIRs) according to their position on a new waiting list…" The announcement also called for support for the implementation of the IPv6 roll-out.

In 2003, Paul Wilson (director of APNIC) stated that, based on then-current rates of deployment, the available space would last for one or two decades.

Since the use of CIDR the Internet Assigned Numbers Authority (IANA) could potentially reclaim these ranges and reissue the addresses in smaller blocks.

[citation needed] ARIN, RIPE NCC and APNIC have a transfer policy, such that addresses can get returned, with the purpose to be reassigned to a specific recipient.

[73][74][75] However, it can be expensive in terms of cost and time to renumber a large network, so these organizations are likely to object, with legal conflicts possible.

[82] The creation of markets to buy and sell IPv4 addresses has been considered to be a solution to the problem of IPv4 scarcity and a means of redistribution.

Some estimates for NAT argue that US ISPs have 5-10 times the number of IPs they need in order to serve their existing customers.

ISP-level NAT may result in multiple-level address translation which is likely to further complicate the use of technologies such as port forwarding used to run Internet servers within private networks.

DS-Lite (Dual-Stack Light) uses tunnels from the customer premises equipment to a network address translator at the ISP.

The AFTR element de-encapsulates the packets and performs network address translation before sending them to the public Internet.