IPv4 address exhaustion

IPv4 address exhaustion timeline

IPv4 address exhaustion is the depletion of the pool of unallocated IPv4 addresses. Because the original Internet architecture had fewer than 4.3 billion addresses available, depletion has been anticipated since the late 1980s when the Internet started experiencing dramatic growth. This depletion is one of the reasons for the development and deployment of its successor protocol, IPv6. ^[1] IPv4 and IPv6 coexist on the Internet.

The IP address space is managed globally by the Internet Assigned Numbers Authority (IANA), and by five regional Internet registries (RIRs) responsible in their designated territories for assignment to end users and local Internet registries, such as Internet service providers. The main market forces that accelerated IPv4 address depletion included the rapidly growing number of Internet users, always-on devices, and mobile devices.

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. ^[2]

The top-level exhaustion occurred on 31 January 2011. ^{[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). ^[13] These RIRs still allocate recovered addresses or addresses reserved for a special purpose. Individual ISPs still have pools of unassigned IP addresses, and could recycle addresses no longer needed by subscribers.

Vint Cerf co-created TCP/IP thinking it was an experiment, and has admitted he thought 32 bits was enough. ^{[14] [15] [16] [17]}

IP addressing

Every node of an Internet Protocol (IP) network, such as a computer, router, or network printer, is assigned an IP address for each network interface, used to locate and identify the node in communications with other nodes on the network. Internet Protocol version 4 provides 2³² (4,294,967,296) addresses. However, large blocks of IPv4 addresses are reserved for special uses and are unavailable for public allocation.

The IPv4 addressing structure provides an insufficient number of publicly routable addresses to provide a distinct address to every Internet device or service. This problem has been mitigated for some time by changes in the address allocation and routing infrastructure of the Internet. The transition from classful network addressing to Classless Inter-Domain Routing delayed the exhaustion of addresses substantially. In addition, network address translation (NAT) permits Internet service providers and enterprises to masquerade private network address space with only one publicly routable IPv4 address on the Internet interface of a main Internet router, instead of allocating a public address to each network device.

Address depletion

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. Each of them increased the demand on the limited supply of addresses, often in ways unanticipated by the original designers of the network.

Mobile devices

As IPv4 increasingly became the de facto standard for networked digital communication and the cost of embedding substantial computing power into hand-held devices dropped, mobile phones have become viable Internet hosts. New specifications of 4G devices require IPv6 addressing.

Always-on connections

Throughout the 1990s, the predominant mode of consumer Internet access was telephone modem dial-up. The rapid increase in the number of the dial-up networks increased address consumption rates, although it was common that the modem pools, and as a result, the pool of assigned IP addresses, were shared amongst a large customer base. By 2007, however, broadband Internet access had begun to exceed 50% penetration in many markets. ^[18] Broadband connections are always active, as the gateway devices (routers, broadband modems) are rarely turned off, so that the address uptake by Internet service providers continued at an accelerating pace.

Internet demographics

The developed world consists of hundreds of millions of households. In 1990, only a small fraction of these had Internet access. Just 15 years later, almost half of them had persistent broadband connections. ^[19] The many new Internet users in countries such as China and India are also driving address exhaustion.

Inefficient address use

Organizations that obtained IP addresses in the 1980s were often allocated far more addresses than they actually required, because the initial classful network allocation method was inadequate to reflect reasonable usage. For example, large companies or universities were assigned class A address blocks with over 16 million IPv4 addresses each, because the next smaller allocation unit, a class B block with 65,536 addresses, was too small for their intended deployments.

Many organizations continue to use public IP addresses for devices not accessible outside their local network. From a global address allocation viewpoint, this is inefficient in many cases, but scenarios exist where this is preferred in the organizational network implementation strategies.^{[ citation needed ]}

Due to inefficiencies caused by subnetting, it is difficult to use all addresses in a block. The host-density ratio, as defined in RFC 3194, is a metric for use of IP address blocks, that is used in allocation policies.

Mitigation efforts

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. ^{[20] [2]}

IPv6, the successor technology to IPv4, was designed to address this problem. It supports approximately 3.4×10³⁸ network addresses. ^[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:

• use of network address translation (NAT) ^[23] which allows a private network to use one public IP address and permitting private addresses in the private network;
• use of private network addressing; ^[24]
• name-based virtual hosting of web sites;
• tighter control by regional Internet registries on the allocation of addresses to local Internet registries;
• network renumbering and subnetting to reclaim large blocks of address space allocated in the early days of the Internet, when the Internet used inefficient classful network addressing. ^[23]

Exhaustion dates and impact

Exhaustion of IPv4 addresses since 1995

IPv4 addresses allocation rate per RIR

Geoff Huston's projection of the evolution of the IP pool for each RIR

On 31 January 2011, the last two unreserved IANA /8 address blocks were allocated to APNIC according to RIR request procedures. This left five reserved but unallocated /8 blocks. ^{[7] [25] [26]} In accord with ICANN policies, IANA proceeded to allocate one of those five /8s to each RIR, exhausting the IANA pool, ^[27] at a ceremony and press conference on 3 February 2011.

The various legacy address blocks with administration historically split among the RIRs were distributed to the RIRs in February 2011. ^[28]

APNIC was the first regional Internet registry to run out of freely allocated IPv4 addresses, on 15 April 2011. This date marked the point where not everyone who needed an IPv4 address could be allocated one. 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. However, IPv6 hosts cannot directly communicate with IPv4 hosts, and have to communicate using special gateway services. This means that general-purpose computers must still have IPv4 access, for example through NAT64, in addition to the new IPv6 address, which is more effort than just supporting IPv4 or IPv6. ^[29]

In early 2011, only 16–26% of computers were IPv6 capable, while only 0.2% preferred IPv6 addressing ^[30] with many using transition methods such as Teredo tunneling. ^[31] About 0.15% of the top million websites were IPv6 accessible in 2011. ^[32] Complicating matters, 0.027% to 0.12% of visitors could not reach dual-stack sites, ^{[33] [34]} but a larger percentage (0.27%) could not reach IPv4-only sites. ^[35] IPv4 exhaustion mitigation technologies include IPv4 address sharing to access IPv4 content, IPv6 dual-stack implementation, protocol translation to access IPv4 and IPv6-addressed content, and bridging and tunneling to bypass single protocol routers. Early signs of accelerated IPv6 adoption after IANA exhaustion are evident. ^[36]

Regional exhaustion

All the RIRs have set aside a small pool of IP addresses for the transition to IPv6 (for example carrier-grade NAT), from which each RIR can typically get at most 1024 in total. ARIN ^[37] and LACNIC ^[38] reserves the last /10 for IPv6 transition. APNIC, and RIPE NCC have reserved the last obtained /8 block for IPv6 transition. AFRINIC reserves a /11 block for this purpose. ^[39] When only this last block remains, the RIR's supply of IPv4 addresses is said to be "exhausted".

Regional Internet registries

A timeline for IPv4 exhaustion in IANA and the RIRs.

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. ^{[46] [47]}

ARIN was exhausted on 24 September 2015. ^[48] ARIN has been unable to allocate large requests since July 2015, but smaller requests were still being met. ^[49] After IANA exhaustion, IPv4 address space requests became subject to additional restrictions at ARIN, ^[50] and became even more restrictive after reaching the last /8 in April 2014. ^[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. ^[52]

On 25 November 2019, RIPE NCC announced ^[53] that it had made its "final /22 IPv4 allocation from the last remaining addresses in our available pool. We have now run out of IPv4 addresses." RIPE NCC will continue to allocate IPv4 addresses, but only "from organisations that have gone out of business or are closed, or from networks that return addresses they no longer need. 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.

Impact of APNIC RIR exhaustion and LIR exhaustion

Systems that require inter-continental connectivity will have to deal with exhaustion mitigation already due to APNIC exhaustion. At APNIC, existing LIRs could apply for twelve months stock before exhaustion when they were using more than 80% of allocated space allocated to them. ^[54] Since 15 April 2011, the date when APNIC reached its last /8 block, each (current or future) member will only be able to get one allocation of 1024 addresses (a /22 block) once. ^{[55] [56]} As the slope of the APNIC pool line on the "Geoff Huston's projection of the evolution of the IP pool for each RIR" chart to the right shows, the last /8 block would have been emptied within one month without this policy. By APNIC policy, each current or future member can receive only one /22 block from this last /8 (there are 16384 /22 blocks in the last /8 block). Since there are around 3000 current APNIC members, and around 300 new APNIC members each year, APNIC expects this last /8 block to last for many years. ^[57] Since the redistribution of recovered space, APNIC is distributing an additional /22 to each member upon request.

The 1,024 addresses in the /22 block can be used by APNIC members to supply NAT44 or NAT64 as a service on an IPv6 network. However at a new large ISP, 1,024 IPv4 addresses might not be enough to provide IPv4 connectivity to all the customers due to the limited number of ports available per IPv4 address. ^[58]

The regional Internet registries (RIRs) for Asia (APNIC) and North America have a policy called the Inter-RIR IPv4 Address Transfer Policy, which allows IPv4 addresses to be transferred from North America to Asia. ^{[59] [60]} The ARIN policy was implemented on 31 July 2012. ^[60]

IPv4 broker businesses have been established to facilitate these transfers. ^[61]

Notable exhaustion advisories

Estimates of the time of complete IPv4 address exhaustion varied widely in the early 2000s. 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. ^[62] In September 2005, a report by Cisco Systems suggested that the pool of available addresses would deplete in as little as 4 to 5 years. ^[63] In the last year before exhaustion, IPv4 allocations were accelerating, resulting in exhaustion trending to earlier dates.

• On 21 May 2007, the American Registry for Internet Numbers (ARIN), the RIR for the US, Canada and a number of island states (mostly in the Caribbean), advised the Internet community that, due to the expected exhaustion in 2010, "migration to IPv6 numbering resources is necessary for any applications which require ongoing availability from ARIN of contiguous IP numbering resources". ^[64] "Applications" include general connectivity between devices on the Internet, as some devices only have an IPv6 address allocated.
• On 20 June 2007, the Latin American and Caribbean Internet Addresses Registry (LACNIC), advised "preparing its regional networks for IPv6" by 1 January 2011, for the exhaustion of IPv4 addresses "in three years time". ^[65]
• On 26 June 2007, the Asia-Pacific Network Information Centre (APNIC), the RIR for the Pacific and Asia, endorsed a statement by the Japan Network Information Center (JPNIC) that to continue the expansion and development of the Internet a move towards an IPv6-based Internet is advised. ^[66] This, with an eye on the expected exhaustion around 2010, would create a great restriction on the Internet. ^[67]
• On 26 October 2007, the Réseaux IP Européens Network Coordination Centre (RIPE NCC), the RIR for Europe, the Middle East, and parts of Central Asia, endorsed a statement ^[68] by the RIPE community urging "the widespread deployment of IPv6 be made a high priority by all stakeholders".
• On 15 April 2009, ARIN sent a letter to all CEO/Executives of companies who have IPv4 addresses allocated informing them that ARIN expects the IPv4 space will be depleted within the next two years. ^[69]
• In May 2009, the RIPE NCC launched IPv6ActNow.org to help explain "IPv6 in terms everyone can understand and providing a variety of useful information aimed at promoting the global adoption of IPv6".
• On 25 August 2009, ARIN announced a joint series event in the Caribbean region to push for the implementation of IPv6. ARIN reported at this time that less than 10.9% of IPv4 address space is remaining. ^[70]
• World IPv6 Day was an event sponsored and organized by the Internet Society and several large content providers to test public IPv6 deployment. It started at 00:00 UTC on 8 June 2011 and ended at 23:59 the same day. The test primarily consisted of websites publishing AAAA records, allowing IPv6 capable hosts to connect to these sites using IPv6, and for misconfigured networks to be corrected.
• World IPv6 Launch Day occurred on 6 June 2012, following the success of World IPv6 Day a year earlier. It involved many more participants and had a more ambitious goal of permanently enabling IPv6 on participant organizations' networks.
• On 24 September 2015 ARIN declared exhaustion of the ARIN IPv4 addresses pool. ^[11]
• On 25 November 2019, RIPE NCC announced ^[53] that it had made its "final /22 IPv4 allocation from the last remaining addresses in our available pool."
• On 21 August 2020, LACNIC announced that it had made its final IPv4 allocation. ^[71]

Post-exhaustion mitigation

By 2008 policy planning for the end-game and post-exhaustion era was underway. ^[72] Several proposals have been discussed to delay shortages of IPv4 addresses:

Reclamation of unused IPv4 space

Before and during the time when classful network design was still used as allocation model, large blocks of IP addresses were allocated to some organizations. 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. However, even if all of these were reclaimed, it would only result in postponing the date of address exhaustion.

Similarly, IP address blocks have been allocated to entities that no longer exist and some allocated IP address blocks or large portions of them have never been used. No strict accounting of IP address allocations has been undertaken, and it would take a significant amount of effort to track down which addresses really are unused, as many are in use only on intranets.^{[ citation needed ]}

Some address space previously reserved by IANA has been added to the available pool. There have been proposals to use the class E network range of IPv4 addresses ^{[76] [77]} (which would add 268.4 million IP addresses to the available pool) but many computer and router operating systems and firmware do not allow the use of these addresses. ^{[63] [78] [79] [80]} For this reason, the proposals have sought not to designate the class E space for public assignment, but instead propose to permit its private use for networks that require more address space than is currently available through RFC 1918.

Several organizations have returned large blocks of IP addresses. Notably, Stanford University relinquished their Class A IP address block in 2000, making 16 million IP addresses available. ^[81] Other organizations that have done so include the United States Department of Defense, BBN Technologies, and Interop. ^[82]

Markets in IP addresses

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. The primary benefits of an IPv4 address market are that it allows buyers to maintain undisrupted local network functionality. ^{[83] [84]} IPv6 adoption, while in progress, is currently still^{[ when? ]} in early stages. ^[85] It requires a significant investment of resources, and poses incompatibility issues with IPv4, as well as certain security and stability risks. ^{[86] [87]}

• The creation of a market in IPv4 addresses would only delay the practical exhaustion of the IPv4 address space for a relatively short time, since the public Internet is still growing.
• The concept of legal ownership of IP addresses as property is explicitly denied by ARIN and RIPE NCC policy documents and by the ARIN Registration Services Agreement, although ownership rights have been postulated based on a letter from the National Science Foundation General Counsel. ^[88] NSF later indicated that the view was not official, and a statement from the Department of Commerce was subsequently issued indicating that "The USG participates in the development of and is supportive of the policies, processes, and procedures agreed upon by the Internet technical community through ARIN." ^{[89] [90]}
• Ad-hoc trading in addresses could lead to fragmented patterns of routing that could increase the size of the global routing table, potentially causing problems for routers with insufficient routing memory resources.
• Microsoft bought 666,624 IPv4 addresses from Nortel's liquidation sale for 7.5 million dollars in a deal brokered by Addrex. ^{[91] [92]} Before exhaustion, Microsoft could have obtained addresses from ARIN without charge, provided that, as per ARIN policy, Microsoft could present ARIN with a need for them. ^[93] The success of this transfer was contingent on Microsoft successfully presenting ARIN with such a justification. The purchase provided Microsoft with a supply that was sufficient for their claimed needs for growth over the next 12 months, rather than for a 3-months' period as is normally requested from ARIN. ^[94]

Transition mechanisms

Main article: IPv6 transition mechanism

As the IPv4 address pool depletes, some ISPs will not be able to provide globally routable IPv4 addresses to customers. Nevertheless, customers are likely to require access to services on the IPv4 Internet. Several technologies have been developed for providing IPv4 service over an IPv6 access network.

In ISP-level IPv4 NAT, ISPs may implement IPv4 network address translation within their networks and assign private IPv4 addresses to customers. This approach may allow customers to keep using existing hardware. 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. ^[95]

However the allocation of private IPv4 addresses to customers may conflict with private IP allocations on the customer networks. Furthermore, some ISPs may have to divide their network into subnets to allow them to reuse private IPv4 addresses, complicating network administration. There are also concerns that features of consumer-grade NAT such as DMZs, STUN, UPnP and application-level gateways might not be available at the ISP level. 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.^{[ citation needed ]}

NAT64 translates IPv6 requests from clients to IPv4 requests. This avoids the need to provision any IPv4 addresses to clients and allows clients that only support IPv6 to access IPv4 resources. However this approach requires a DNS server with DNS64 capability and cannot support IPv4-only client devices.

DS-Lite (Dual-Stack Light) uses tunnels from the customer premises equipment to a network address translator at the ISP. ^[96] The consumer premises equipment encapsulates the IPv4 packets in an IPv6 wrapper and sends them to a host known as the AFTR element. The AFTR element de-encapsulates the packets and performs network address translation before sending them to the public Internet. The NAT in the AFTR uses the IPv6 address of the client in its NAT mapping table. This means that different clients can use the same private IPv4 addresses, therefore avoiding the need for allocating private IPv4 IP addresses to customers or using multiple NATs.

Address plus Port allows stateless sharing of public IP addresses based on TCP/UDP port numbers. Each node is allocated both an IPv4 address and a range of port numbers to use. Other nodes may be allocated the same IPv4 address but a different range of ports. The technique avoids the need for stateful address translation mechanisms in the core of the network, thus leaving end users in control of their own address translation. ^[97]

Long-term solution

Deployment of IPv6 is the standards-based solution to the IPv4 address shortage. ^[8] IPv6 is endorsed and implemented by all Internet technical standards bodies and network equipment vendors. It encompasses many design improvements, including the replacement of the 32-bit IPv4 address format with a 128-bit address which provides an addressing space without limitations for the foreseeable future. IPv6 has been in active production deployment since June 2006, after organized worldwide testing and evaluation in the 6bone project ceased. Interoperability for hosts using only IPv4 protocols is implemented with a variety of IPv6 transition mechanisms.

See also

• List of assigned /8 IPv4 address blocks
• 512K Day – an event in 2014, involving the exhaustion of the default allocation of hardware routing slots on many routers

References

1. Li, Kwun-Hung; Wong, Kin-Yeung (14 June 2021). "Empirical Analysis of IPv4 and IPv6 Networks through Dual-Stack Sites". Information. 12 (6): 246. doi: 10.3390/info12060246 . ISSN   2078-2489.
2. Niall Richard Murphy; David Malone (2005). IPv6 network administration. O'Reilly Media. pp. xvii–xix. ISBN   0-596-00934-8.
3. Smith, Lucie; Lipner, Ian (3 February 2011). "Free Pool of IPv4 Address Space Depleted". Number Resource Organization . Archived from the original on 13 August 2011. Retrieved 3 February 2011.
4. "Available Pool of Unallocated IPv4 Internet Addresses Now Completely Emptied" (PDF). ICANN . 3 February 2011. Archived (PDF) from the original on 8 August 2011. Retrieved 10 September 2016.
5. "Major Announcement Set on Dwindling Pool of Available IPv4 Internet Addresses" (PDF). Archived (PDF) from the original on 13 March 2011. Retrieved 10 September 2016.
6. ICANN, nanog mailing list. "Five /8s allocated to RIRs – no unallocated IPv4 unicast /8s remain". Archived from the original on 27 August 2011. Retrieved 3 February 2011.
7. Huston, Geoff. "IPv4 Address Report, daily generated". Archived from the original on 6 August 2011. Retrieved 16 January 2011.
8. "Two /8s allocated to APNIC from IANA". APNIC. 1 February 2010. Archived from the original on 7 August 2011. Retrieved 3 February 2011.
9. "APNIC IPv4 Address Pool Reaches Final /8". APNIC. 15 April 2011. Archived from the original on 7 August 2011. Retrieved 15 April 2011.
10. "LACNIC Enters IPv4 Exhaustion Phase - The Number Resource Organization". Archived from the original on 13 May 2016. Retrieved 10 September 2016.
11. "ARIN IPv4 Free Pool Reaches Zero". American Registry for Internet Numbers. 24 September 2015. Archived from the original on 25 September 2015. Retrieved 25 September 2015.
12. "IPv4 Exhaustion - AFRINIC". Regional Internet Registry for Africa. 17 January 2020. Archived from the original on 15 September 2020. Retrieved 18 September 2020.
13. "The RIPE NCC has run out of IPv4 Addresses". Réseaux IP Européens Network Coordination Centre. 25 November 2019. Archived from the original on 25 November 2019. Retrieved 25 November 2019.
14. Perry, Tekla (7 May 2023). "Vint Cerf on 3 Mistakes He Made in TCP/IP". IEEE Spectrum . Archived from the original on 8 May 2023. Retrieved 8 May 2023.
15. Moses, Asher; Grubb, Ben (21 January 2011). "Internet Armageddon all my fault: Google chief". Sydney Morning Herald . Archived from the original on 3 February 2023. Retrieved 8 May 2023.
16. Trout, Christopher (26 January 2011). "Vint Cerf on IPv4 depletion: 'Who the hell knew how much address space we needed?'". Engadget . Archived from the original on 3 February 2023. Retrieved 8 May 2023.
17. "Google IPv6 Conference 2008: What will the IPv6 Internet look like?". Google TechTalks channel on YouTube . 29 January 2008. Cerf quote starts 13½ minutes into the video. I'm serious, the decision to put a 32-bit address space on there was the result of a year's battle among a bunch of engineers who couldn't make up their minds about 32, 128 or variable length. And after a year of fighting I said - I'm now at ARPA, I'm running the program, I'm paying for this stuff and using American tax dollars - and I wanted some progress because we didn't know if this is going to work. So I said - 32 bits, it is enough for an experiment, it is 4.3 billion terminations - even the defense department doesn't need 4.3 billion of anything and it couldn't afford to buy 4.3 billion edge devices to do a test anyway. So at the time I thought we were doing a experiment to prove the technology and that if it worked we'd have an opportunity to do a production version of it. Well - it just escaped! - it got out and people started to use it and then it became a commercial thing. So, this [IPv6] is the production attempt at making the network scalable. Only 30 years later.
18. Ferguson, Tim (18 February 2007). "Broadband adoption passes halfway mark in U.S." CNET news.com. Archived from the original on 15 November 2013. Retrieved 10 November 2010.
19. "Projections of the Number of Households and Families in the United States: 1995 to 2010" (PDF). April 1996. Archived (PDF) from the original on 17 October 2010. Retrieved 10 November 2010.
20. Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan. doi: 10.17487/RFC4632 . RFC 4632.
21. Mark Townsley (21 January 2011). "World IPv6 Day: Working Together Towards a New Internet Protocol". Archived from the original on 14 August 2011. Retrieved 8 May 2011.
22. S.H. Gunderson (October 2008). "Global IPv6 Statistics – Measuring the current state of IPv6 for ordinary users" (PDF). Archived (PDF) from the original on 15 August 2011. Retrieved 10 November 2010.
23. Scott Hogg (9 November 2011). "Techniques for Prolonging the Lifespan of IPv4". Network World . Archived from the original on 26 April 2024. Retrieved 20 September 2016.
24. Address Allocation for Private Internets. sec. 4. doi: 10.17487/RFC1918 . RFC 1918.
25. "IANA IPv4 Address Space Registry". IANA. IANA IPv4 Address Space Registry. Archived from the original on 5 July 2019. Retrieved 31 January 2011.
26. Stephen Lawson (31 January 2011). "Address allocation kicks off IPv4 endgame". Computerworld . Archived from the original on 9 May 2012. Retrieved 1 February 2011.
27. "Global Policy for the Allocation of the Remaining IPv4 Address Space". Archived from the original on 10 August 2011. Retrieved 1 February 2011.
28. "The IPv4 Depletion site "Blog Archive" Status of the various pool". Ipv4depletion.com. 3 December 2010. Archived from the original on 19 January 2012. Retrieved 2 December 2011.
29. "IPv6 and Transitional Myths". Fix6.net. 24 November 2010. Archived from the original on 23 July 2011. Retrieved 3 February 2011.
30. "ISP Column - May 2011". Potaroo.net. Archived from the original on 31 October 2011. Retrieved 2 December 2011.
31. Huston, Geoff. "Stacking it Up: Experimental Observations on the operation of Dual Stack Services in today's Network" (PDF). Archived from the original (PDF) on 6 July 2011. Retrieved 25 February 2011.
32. "IPv6 Measurements – A Compilation – RIPE Labs". RIPE . 9 December 2009. Archived from the original on 21 January 2012. Retrieved 2 December 2011.
33. "IPV6 Test – Introductie". Ipv6test.max.nl. Archived from the original on 4 April 2009. Retrieved 2 December 2011.
34. Igor Gashinsky (1 February 2011), World IPv6 Day: A Content Provider Perspective (PDF), archived (PDF) from the original on 27 July 2011, retrieved 1 September 2016
35. "ISP Column – April 2010". Potaroo.net. Archived from the original on 28 October 2011. Retrieved 2 December 2011.
36. Carolyn Duffy Marsan (7 February 2011). "Suddenly everybody's selling IPv6". Network World . Archived from the original on 4 January 2013.
37. "ARIN IPv4 Countdown Plan". ARIN. 3 February 2011. Archived from the original on 25 June 2014. Retrieved 16 June 2014.
38. "LACNIC". Archived from the original on 4 September 2016. Retrieved 10 September 2016.
39. "IPv4 Address Report". Potaroo.net. Archived from the original on 6 August 2011. Retrieved 5 May 2014.
40. "APNIC's IPv4 pool usage". APNIC . Archived from the original on 14 January 2011. Retrieved 2 December 2011.
41. "APNIC IPv4 Address Pool Reaches Final /8". APNIC . 15 April 2011. Archived from the original on 17 April 2011. Retrieved 20 July 2022.
42. "APNIC Allocation Rate (smoothed)". Archived from the original on 24 July 2011. Retrieved 10 September 2016.
43. "The End" (PDF). Archived (PDF) from the original on 28 April 2011. Retrieved 10 September 2016.
44. "RIR pool exhaust rates (zoomed)". Archived from the original on 11 June 2016. Retrieved 10 September 2016.
45. "RIPE NCC Begins to Allocate IPv4 Address Space From the Last /8". RIPE. Archived from the original on 16 September 2012. Retrieved 19 August 2013.
46. "IPv4 Address Report retrieved June 16, 2014". Archived from the original on 6 August 2011. Retrieved 27 January 2007.
47. "No more IPv4 addresses in Latin America and the Caribbean". Archived from the original on 3 August 2014. Retrieved 16 June 2014.
48. "IPV4 Address Report". Archived from the original on 6 August 2011. Retrieved 27 January 2007.
49. "It's official: North America out of new IPv4 addresses". 2 July 2015. Archived from the original on 5 July 2015. Retrieved 6 July 2015.
50. "information on ARIN website". ARIN. Archived from the original on 28 June 2011. Retrieved 3 February 2011.
51. AFRINIC. "AFRINIC Enters IPv4 Exhaustion Phase 1". www.afrinic.net. Retrieved 2 September 2022.
52. "AFRINIC enters IPv4 Exhaustion Phase 2". 13 January 2020. Retrieved 2 September 2022.
53. "The RIPE NCC has run out of IPv4 Addresses". RIPE NCC . 25 November 2019. Archived from the original on 2 April 2020. Retrieved 20 July 2022.
54. "APNIC – Policies for IPv4 address space management in the Asia Pacific region". APNIC. Archived from the original on 18 November 2011. Retrieved 2 December 2011.
55. "APNIC – Policies for IPv4 address space management in the Asia Pacific region". APNIC. Archived from the original on 18 November 2011. Retrieved 2 December 2011.
56. "APNIC – IPv4 exhaustion details". APNIC. 3 February 2011. Archived from the original on 2 December 2011. Retrieved 2 December 2011.
57. "IPv4 exhaustion details". APNIC. Archived from the original on 15 December 2010. Retrieved 2 February 2011.
58. "No more addresses: Asia-Pacific region IPv4 well runs dry". Ars Technica. 15 April 2011. Archived from the original on 22 August 2011. Retrieved 16 April 2011.
59. Tomohiro Fujisaki (24 February 2011). "prop-095-v003: Inter-RIR IPv4 address transfer proposal". Archived from the original on 25 March 2012. Retrieved 9 November 2011.
60. "Draft Policy ARIN-2011-1: ARIN Inter-RIR Transfers". 14 October 2011. Archived from the original on 6 April 2012. Retrieved 9 November 2011.
61. "APNIC Registered IPV4 Brokers". Archived from the original on 11 September 2015.
62. Lui, John (24 June 2003). "Exec: No shortage of Net addresses". ZDNet News. Archived from the original on 5 April 2005. Retrieved 20 July 2022.
63. Hain, Tony. "A Pragmatic Report on IPv4 Address Space Consumption". Archived from the original on 6 August 2011. Retrieved 14 November 2007.
64. "ARIN Board Advises Internet Community on Migration to IPv6". ARIN (Press release). 21 May 2007. Archived from the original on 15 October 2008. Retrieved 1 July 2007.
65. "LACNIC announces the imminent depletion of the IPv4 addresses". LACNIC (Press release). 21 June 2007. Archived from the original on 29 June 2012. Retrieved 1 July 2007.
66. "JPNIC releases statement on IPv4 consumption". APNIC (Press release). 26 June 2007. Archived from the original on 3 April 2012. Retrieved 1 July 2007.
67. "About IPv4 address exhaustion in Internet Registries" (PDF). JPNIC (Press release) (in Japanese). 19 June 2007. Archived (PDF) from the original on 7 October 2007. Retrieved 1 July 2007.
68. "RIPE 55 – Meeting Report". RIPE NCC . 26 October 2007. Archived from the original on 4 September 2011. Retrieved 2 February 2011.
69. "Notice of Internet Protocol version 4 (IPv4) Address Depletion" (PDF). Archived from the original (PDF) on 7 January 2010. Retrieved 3 February 2011.
70. White, Lauren (25 August 2009). "ARIN and Caribbean Telecommunications Union Host Premier Internet Community Meeting". Archived from the original on 30 April 2015. Retrieved 27 August 2009. The global Internet community is playing a crucial role in the effort to raise awareness of IPv4 depletion and the plan to deploy IPv6, as only 10.9% of IPv4 address space currently remains.
71. "IPv4 Exhaustion: LACNIC Has Assigned the Last Remaining Address Block". www.lacnic.net. Archived from the original on 24 September 2020. Retrieved 21 August 2020.
72. "Proposed Global Policy for the Allocation of the Remaining IPv4 Address Space". RIPE NCC. 3 March 2008. Archived from the original on 23 November 2010. Retrieved 10 November 2010.
73. "APNIC transfer policy". APNIC. 10 February 2010. Archived from the original on 5 June 2015. Retrieved 3 February 2011.
74. "ARIN transfer policy". ARIN. Archived from the original on 13 May 2011. Retrieved 3 February 2011.
75. "Ripe FAQ". RIPE. Archived from the original on 19 August 2011. Retrieved 3 February 2011.
76. Wilson, Paul; Michaelson, George; Huston, Geoff (29 September 2008). "Redesignation of 240/4 from "Future Use" to "Limited Use for Large Private Internets" (expired draft)". Archived from the original on 18 October 2010. Retrieved 5 April 2010.
77. V. Fuller; E. Lear; D. Meyer (24 March 2008). "Reclassifying 240/4 as usable unicast address space (expired draft)". IETF . Archived from the original on 20 October 2009. Retrieved 10 November 2010.
78. "Address Classes". Microsoft . Archived from the original on 15 September 2008. Retrieved 14 November 2007.
79. van Beijnum, Iljitsch. "IPv4 Address Consumption". Archived from the original on 10 September 2011. Retrieved 14 November 2007.
80. "TCP/IP Overview". Cisco Systems. Archived from the original on 17 August 2011. Retrieved 14 November 2007.
81. Marsan, Carolyn (22 January 2000). "Stanford move rekinds 'Net address debate". Computerworld . Archived from the original on 10 February 2015. Retrieved 29 June 2010.
82. "ARIN Recognizes Interop for Returning IPv4 Address Space". ARIN. 20 October 2010. Archived from the original on 3 June 2011. Retrieved 3 February 2011.
83. Phil Lodico (15 September 2011). "Pssst! Rare IPv4 Addresses For Sale! Get Them While You Can!". Forbes. Archived from the original on 5 May 2017. Retrieved 1 September 2017.
84. Bjoran, Kristina (27 July 2011). "The State of the Internet: IPv4 Won't Die". Archived from the original on 17 June 2013.
85. Steve Wexler (18 October 2011). "IPv6: Unstoppable Force Meets Immovable Object". Archived from the original on 20 January 2012. Retrieved 5 December 2011.
86. David Braue (20 October 2011). "IPv6 will change network attack surface, albeit slowly: Huston". Archived from the original on 22 November 2011. Retrieved 5 December 2011.
87. Elizabeth Harrin (22 September 2011). "IPv6 Will Cause Some Security Headaches". Archived from the original on 28 November 2011. Retrieved 5 December 2011.
88. Mueller, Milton (22 September 2012). "It's official: Legacy IPv4 address holders own their number blocks". Internet governance Project. Archived from the original on 4 April 2013. Retrieved 22 February 2013.
89. Andrew, Dul. "Legacy IPv4 Address standing with USG". Archived from the original on 31 May 2013. Retrieved 22 February 2013.
90. Strickling, Lawrence. "United States Government's Internet Protocol Numbering Principles". USG/NTIA . Archived from the original on 21 February 2013. Retrieved 22 February 2013.
91. Chloe Albanesius (25 March 2011). "Microsoft Spends $7.5M on 666K Nortel IPv4 Addresses". PCMag . Archived from the original on 11 July 2017. Retrieved 1 September 2017.
92. Kevin Murphy (24 March 2011). "Microsoft spends $7.5 million on IP addresses". Domain Incite. Archived from the original on 27 August 2011. Retrieved 24 March 2011.
93. "Resource Transfers: Returning Unneeded IPv4 Address Space". ARIN. Archived from the original on 13 May 2011. Retrieved 1 February 2011.
94. Jaikumar Vijayan (25 March 2011). "IPv4 address transfers must meet policy, ARIN chief says". Archived from the original on 19 January 2012. Retrieved 26 March 2011.
95. Ramuglia, Gabriel (16 February 2015). "Why IPv4 is Here to Stay, Part 2: Show Me the Money". The Web Host Industry Review. Archived from the original on 20 February 2015. Retrieved 27 February 2015.
96. RFC 6333 - Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion
97. Bush, Randy (August 2011). Bush, R (ed.). "The Address plus Port (A+P) Approach to the IPv4 Address Shortage". tools.ietf.org. doi:10.17487/RFC6346. Archived from the original on 3 December 2020. Retrieved 12 January 2021.

External links

• Official current state of /8 allocations, as maintained by IANA
• ICANN recovers Large Block of Internet Addresses (14.0.0.0/8) 2008-02-10
• Global Policy Proposal for Remaining IPv4 Address Space – Background Report 2008-09-08
• RIR IPv4 status: APNIC RIPE
• IPv6 vs. carrier-grade NAT/squeezing more out of IPv4
• IP addressing in China and the myth of address shortage Archived 3 March 2016 at the Wayback Machine