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IPv4 address exhaustion

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IPv4 address exhaustion is the decreasing supply of unallocated Internet Protocol Version 4 (IPv4) addresses available at the Internet Assigned Numbers Authority (IANA) and the regional Internet registries (RIRs) for assignment to end users and local Internet registries, such as Internet service providers. IPv4 provides for approximately 4 billion addresses, and with the allocation granularity of /8 blocks, each approximately 16.8 million addresses, IANA's primary address pool exhaustion is projected for early 2011.[1][2] In January 2011, only seven allocation blocks remain available, or less than 3% of the IPv4 address space.[3]

The depletion of the IPv4 allocation pool has been a concern since the late 1980s when the Internet started to experience dramatic growth. 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.[4][5]

The anticipated shortage has been the driving factor in creating and adopting several new technologies, including classful networks in the 1980s,[citation needed] Classless Inter-Domain Routing (CIDR) methods in 1993, network address translation (NAT) and a new version of the Internet Protocol, IPv6, in 1998.[5]

The transition of the Internet to IPv6 is the only practical and readily available long-term solution to IPv4 address exhaustion. Although the predicted IPv4 address exhaustion was approaching its final stages, most providers of Internet services and software vendors were just beginning IPv6 deployment in 2008.[6] Several large content providers are going to test public IPv6 deployment on "World IPv6 Day", June 8, 2011.[7][8]

IP addressing

Every host on an IP network, such as a computer or networked printer, is assigned an IP address that is used to communicate with other hosts on the same network or globally. Internet Protocol version 4 provides 232 (approximately 4.3 billion) 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. Classful networking and particularly Classless Inter-Domain Routing delayed the exhaustion of addresses substantially.

In addition, network address translation permitted large Internet service providers to allocate only one public IP address to each of their customers, by masquerading the customer network behind this address with specially configured customer-premise Internet routers.

Address depletion

While the primary reason for IPv4 address exhaustion is insufficient design capacity 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, the cost of embedding substantial computing power into handheld 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 dialup. The rapid growth of the dialup 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 larger customer base. By 2007, however, broadband Internet access had begun to exceed 50% penetration in many markets.[9] 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
There are hundreds of millions of households in the developed world. In 1990, only a small fraction of these had Internet connectivity. Just 15 years later, almost half of them had persistent broadband connections.[10] 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 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 65536 addresses, was too small for their intended deployments.
Many organizations continue to utilize 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.
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 utilization of IP address blocks, that is used in allocation policies.
Virtualization
With advances in hardware performance and processor features of server systems and the advent of sophisticated hardware abstraction layers it became possible to host many instantiations of an operating system on a single computer. Each of these systems may require a public IP address.

Mitigation efforts

Some methods of mitigation of IPv4 address exhaustion have been

Several organizations have returned large blocks of IP addresses. Notably, Stanford University relinquished their Class A IP block in 2000, making 16 million IP addresses available.[11] Other organizations that have done so include the United States Department of Defense, BBN Technologies, and Interop.[citation needed]

Exhaustion date

Exhaustion of IPv4 addresses since 1995.
IPv4 addresses allocation rate per RIR.

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.[12] 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.[13] In the last year before exhaustion, IPv4 allocations were accelerating, resulting in exhaustion trending to earlier dates.

As of 22 January 2011, seven IANA assignment blocks (/8 CIDR blocks) remain unallocated and APNIC is eligible for two new blocks.[2][14]

According to IANA policies each one of the last five remaining blocks is to be distributed to the five RIR's, respectively, exhausting the IANA pool. At the RIR level, APNIC is expected to be exhausted first within 8 to 9 months. By early 2012, new devices and services are expected to appear on the Internet that are only reachable by IPv6. These will only be accessible from the IPv4 Internet if older hosts that cannot implement IPv6 utilize special translator gateway services.

The time remaining until the first RIR exhaustion is a short time for the entire industry to transition to IPv6. This situation is aggravated by the likelihood that until exhaustion there will be no significant consumer demand for IPv6. David Conrad, the general manager of IANA, acknowledges: "I suspect we are actually beyond a reasonable time frame where there won't be some disruption. Now it's more a question of how much."[15] Geoff Huston claims the transition to IPv6 should have started much earlier, such that by the exhaustion date it would be completed, with all devices IPv6-capable, and IPv4 being phased out.[16]

Notable exhaustion advisories

  • On May 21, 2007, the American Registry for Internet Numbers (ARIN), the North American RIR, 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".[17] "Applications" includes general connectivity between devices on the Internet, as some devices only have an IPv6 address allocated.
  • On June 20, 2007, the Latin American and Caribbean Internet Addresses Registry (LACNIC), advised "preparing its regional networks for IPv6" by January 1, 2011, for the exhaustion of IPv4 addresses "in three years time".[18]
  • On June 26, 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. This with an eye on the expected exhaustion around 2010 which will create a great restriction on the Internet.[19][20]
  • On April 15, 2009, the American Registry for Internet Numbers (ARIN), the North American RIR, 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.[21]
  • On August 25, 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.[22]
  • The RIPE NCC, the Regional Internet Registry (RIR) covering Europe, the Middle East and parts of Central Asia, has been working to inform all stakeholders about the urgent need to deploy IPv6 for many years. On 26 October 2007, the RIPE community issued a statement urging "the widespread deployment of IPv6 be made a high priority by all stakeholders". In May 2009, it launched a one-stop-shop for IPv6 news, tools and resources called IPv6ActNow.org. The RIPE NCC works closely with the European Commission, the OECD, Law Enforcement Agencies and a number of government and non-governmental stakeholders as an advisor on IPv6 deployment and other Internet number resource issues. The RIPE NCC also offers comprehensive information about IPv4 exhaustion on its website.
  • Tony Hain of networking equipment manufacturer Cisco Systems predicts the exhaustion date of the unallocated IANA pool to be early in 2011 (updated monthly).[23] His predictions use the same data source as Geoff Huston's, but the trends are generated from different subsets, and account for the different distribution rules for the "last 5".[24]

Endgame

As of 2008, a policy process has started for the end-game and post-exhaustion era.[25]

Several proposals have been discussed to mitigate end game 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. The Internet Assigned Numbers Authority (IANA) could potentially reclaim these ranges and reissue the addresses in smaller blocks.[citation needed] ARIN, the North American Internet registry, has a transfer policy, such that addresses can get returned to ARIN, with the purpose to be reassigned to a specific recipient.[citation needed] However, it can be expensive in terms of cost and time to renumber a large network, so these organizations will likely 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 or never used them. No strict accounting of IP address allocations has been undertaken, and it would take quite a bit of effort to track down which addresses really are unused, as many are only in use on intranets.[citation needed]

Some address space that was previously reserved by IANA has been added to the available pool. There have been proposals to use the class E network addresses,[26][27] but many computer and router operating systems and firmware do not allow the use of these addresses.[28][29][30][31][32] For this reason, the proposals have sought not to designate the class E space for public assignment, but instead propose to permit private use for networks that require more address space than is currently available through RFC 1918.

ISP-wide network address translation

When Internet service providers (ISPs) implement network address translation within their network, rather than at the demarcation to customer networks, they may allocate private addresses to customers and need only one global scope address for a potentially large group of customers. However, many customers must use the gateway for traffic to the Internet.[33]

This has been successfully implemented in some countries like Russia, where many broadband providers now use Carrier Grade NAT, and offer publicly routable IP address at an additional cost.[citation needed] Similarly, Research In Motion (RIM), the maker of BlackBerry devices, currently routes all Blackberry data to central network operating centers for encryption and decryption purposes; this has the side effect of reducing the number public IP addresses necessary assigned.

However, ISP-wide NAT is not scalable, and limited to the number of ports available (approximately 65000) in the Transport Layer protocols. In addition, network address translation is not suitable for all applications.

Markets in IP addresses

The creation of markets to buy and sell IPv4 addresses has been proposed many times as an efficient means of allocation. The primary benefit of an address market would be that IPv4 addresses would continue to be available, although the market price of addresses would be expected to rise over time. These schemes have major drawbacks that have prevented their implementation:[34]

  • 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. This implies that absolute exhaustion of the IPv4 space would follow within at most a couple of years after the exhaustion of addresses for new allocations.
  • The concept of legal "ownership" of IP addresses as property is explicitly denied by ARIN and RIPE policy documents and by the ARIN Registration Services Agreement. It is not even clear in which country's legal system the lawsuits would be resolved.
  • The administration of such a scheme is outside the experience of the current regional address registries.
  • Ad-hoc trading in addresses would lead to fragmented patterns of allocation that would vastly expand the global routing table, resulting in severe routing problems for many network operators which still use older routers with limited forwarding information base memory or low-powered routing processors. This large cost placed on everyone who uses the Internet by those that buy/sell IP addresses is a negative economic externality that any market would need to correct for.
  • Trading in IP blocks that are large enough to prevent fragmentation problems would reduce the number of potentially tradeable units to a few million at most.
  • The cost of changing from one set of IP addresses to another is very high, reducing the market liquidity. Organizations that can potentially reorganize their usage of IP addresses to free them up so that they can be sold will demand a high price and, once bought, will not be resold without a large profit. The cost of renumbering an organization's IP address space each time is comparable to the cost of switching to IPv6 once.[citation needed]

Long-term solution

The deployment of IPv6 is currently the only viable solution to the IPv4 address shortage. IPv6 is endorsed and implemented by all Internet technical standards bodies and network equipment vendors.[citation needed] It encompassed many design improvements, including the replacement of the 32-bit IPv4 address format, which allows 4.3 billion possible addresses, with a 128-bit address for a theoretical capacity of 3.4×1038 addresses. IPv6 has been in active production deployment since June 2006, when organized worldwide efforts of testing and evaluation (6bone) ceased.

See also

References

  1. ^ Arano, Takashi. "IPv4 Exhaustion Counter (English)". iNetCore (INTEC Systems Institute, Inc.). Retrieved 2011-01-20.
  2. ^ a b Huston, Geoff. "IPv4 Address Report, daily generated". Retrieved 2011-01-16.
  3. ^ "IANA IPv4 Address Space Registry". IANA. 4 January 2011. Retrieved 20 January 2011.
  4. ^ RFC 4632
  5. ^ a b Niall Richard Murphy, David Malone (2005). IPv6 network administration. O'Reilly Media, Inc. pp. xvii–xix. ISBN 0596009348.
  6. ^ S.H. Gunderson (2008-10). "Global IPv6 Statistics - Measuring the current state of IPv6 for ordinary users" (PDF). Retrieved 2010-11-10. {{cite web}}: Check date values in: |date= (help)
  7. ^ "About World IPv6 Day".
  8. ^ "World IPv6 Day - How to Participate". Internet Society. Retrieved 26 January 2011.
  9. ^ Ferguson, Tim (2007-02-18). "Broadband adoption passes halfway mark in U.S." CNET News.com. Retrieved 2010-11-10.
  10. ^ "Projections of the Number of Households and Families in the United States: 1995 to 2010" (PDF). 1996-04. Retrieved 2010-11-10. {{cite web}}: Check date values in: |date= (help)
  11. ^ Marsan, Carolyn. "Stanford move rekinds 'Net address debate". Network World. Retrieved 2010-06-29.
  12. ^ Exec: No shortage of Net addresses By John Lui, CNETAsia
  13. ^ A Pragmatic Report on IPv4 Address Space Consumption by Tony Hain, Cisco Systems
  14. ^ Stephan Lagerholm. "The Report". The IPv4 Depletion Site. Retrieved 2011-01-19.
  15. ^ Ben Arnoldy. "IP address shortage to limit Internet access". Retrieved 2010-11-13.
  16. ^ Geoff Huston (2007-09-24). "IPv4 Unallocated Address Space Exhaustion" (PDF). Retrieved 2010-11-13.
  17. ^ "ARIN Board Advises Internet Community on Migration to IPv6" (Press release). American Registry for Internet Numbers (ARIN). 2007-05-21. Retrieved 2007-07-01.
  18. ^ "LACNIC announces the imminent depletion of the IPv4 addresses" (Press release). Latin American and Caribbean Internet Addresses Registry (LACNIC). 2007-06-21. Retrieved 2007-07-01.
  19. ^ "JPNIC releases statement on IPv4 consumption" (Press release). Asia-Pacific Network Information Centre (APNIC). 2007-06-26. Retrieved 2007-07-01.
  20. ^ "About IPv4 address exhaustion in Internet Registries" (PDF) (Press release) (in Japanese). Japan Network Information Center (JPNIC). 2007-06-19. Retrieved 2007-07-01.
  21. ^ Notice of Internet Protocol version 4 (IPv4) Address Depletion
  22. ^ White, Lauren (2009-08-25). "ARIN and Caribbean Telecommunications Union Host Premier Internet Community Meeting". Archived from the original on 2009-08-27. 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. {{cite news}}: Cite has empty unknown parameters: |trans_title= and |coauthors= (help)
  23. ^ Hain, Tony. "IPv4 Address Pool, monthly generated" (PDF). Retrieved 2011-01-19.
  24. ^ Hain, Tony. "IPv4 Address Pool observations".
  25. ^ "Proposed Global Policy for the Allocation of the Remaining IPv4 Address Space". RIPE. 2008-03-03. Retrieved 2010-11-10.
  26. ^ Wilson, Paul. "Redesignation of 240/4 from "Future Use" to "Limited Use for Large Private Internets" (expired draft)". Retrieved 2010-04-05. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  27. ^ V. Fuller, E. Lear, D. Meyer (2008-03-24). "Reclassifying 240/4 as usable unicast address space (expired draft)". IETF. Retrieved 2010-11-10.{{cite web}}: CS1 maint: multiple names: authors list (link)
  28. ^ "Address Classes". Windows 2000 Resource Kit. Microsoft. Retrieved 2007-11-14.
  29. ^ Hain, Tony. "A Pragmatic Report on IPv4 Address Space Consumption". Retrieved 2007-11-14.
  30. ^ van Beijnum, Iljitsch. "IPv4 Address Consumption". Retrieved 2007-11-14.
  31. ^ "TCP/IP Overview". Cisco Systems, Inc. Retrieved 2007-11-14.
  32. ^ "Intel Express 10 Switch TCP/IP Basics". Intel Corporation. Retrieved 2007-11-14.
  33. ^ Yamagata, I.; Miyakawa, S.; Nakagawa, A,; Ashida, H. "Common requirements for IP address sharing schemes". IETF. July 12, 2010. Retrieved December 3, 2010.
  34. ^ RFC 2008
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