IPv4 address
exhaustion
http://en.wikipedia.org/wiki/I
Pv4_address_exhaustion
IPv4 address exhaustion
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Depletion of the pool of unallocated IPv4
(Internet Protocol Version 4) addresses.
The IP address space is managed by the Internet
Assigned Numbers Authority (IANA) globally, 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.
IANA also manages autonomous system (AS)
numbers, root zone management in the Domain
Name System (DNS), media types, and other
IP-related symbols and numbers
IANA is operated by the Internet Corporation for
Assigned Names and Numbers, ICANN.
Regional Internet Registry (RIR)
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An organization that manages the
allocation and registration of Internet
number resources within a particular
region of the world.
Internet number resources include IP
addresses and autonomous system
(AS) numbers.
Regional Internet Registry (RIR)
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African Network Information Centre (AfriNIC):
• Africa
American Registry for Internet Numbers (ARIN):
• the United States, Canada, and several parts of
the Caribbean region.
Asia-Pacific Network Information Centre (APNIC):
• Asia, Australia, New Zealand, and neighboring
countries
Latin America and Caribbean Network Information
Centre (LACNIC):
• Latin America and parts of the Caribbean region
Réseaux IP Européens Network
Coordination Centre (RIPE):
• Europe, the Middle East, and
Central Asia
IPv4 address exhaustion
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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. In
accord with ICANN policies, IANA proceeded to
allocate one of those five /8s to each RIR,
exhausting the IANA pool
IPv4 address exhaustion
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At a news conference in Miami (February 3, 2011)
the ICANN announced (released-PDF) that it has
distributed the last batch of its remaining IPv4
addresses to the world’s five RIRs that manage IP
addresses in different regions. These Registries
will begin assigning the final IPv4 addresses within
their regions until they run out completely.
APNIC is expected to be the first RIR to exhaust its
allocated pool with assignment to customers in
mid-2011, Europe will be next, probably towards
the end of 2011, and North America will follow
sometime in 2012.
APNIC IPs exhaustion
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As of March 6, 2011, APNIC had 3.89 /8 blocks left.
APNIC used 1.4 /8 blocks in January 2011.
The last /8 block
• APNIC will continue normal allocation until the last free /8 block.
• Then, APNIC will only allocate one /22 block (1024 IPs, nominal
minimum allocation size), to each local Internet registry (LIR).
• Typically, 99.2% of address space is allocated in larger blocks,
accounting for 57% of allocations.
• currently 3000 LIRs in APNIC, 300 new LIRs added in 2010.
Since there are 16384 /22 blocks in final /8 block, APNIC
expects this last /8 block to last for many years to assist
deployment of IPv6.
• The time when APNIC reaches its final /8 block is generally
regarded as the main exhaustion event in IPv4 history, as LIR
organizations will have a much harder time getting their new
systems or customers publicly online on the IPv4 Internet.
• Moreover, the 300 new large and small LIRs per year at APNIC
will only be able to obtain 1024 addresses from APNIC. This will
have an impact on all organizations and their customers
worldwide due to the requirement for inter-network
communication.
APNIC IPs exhaustion
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Predictions
• APNIC announced on 1/31/2011, it expects to be
down to the last /8 within three to six months.
Geoff Huston's (APNIC) daily generated report
currently predicts August.
• The predicted date has however steadily been
getting earlier in the last year, with the exhaustion
date trending to May or June (Moreover, his analysis
wrongly assumes no special policy for the last /8
which will be reached earlier than the specified date).
• Tony Haine (Cisco Systems) is making semi-weekly
updated graphs predicting mid-April. (His analysis
does however not consider the use of the 1.57 /8
blocks from the various/legacy pool.) Stephan
Lagerholm's depletion-Tool is daily updated and
predicts August in its default setting.
APNIC IPs exhaustion
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RIR-shopping
• When APNIC has only one /8 available, some
organizations that usually request address space
from APNIC but have a presence in another territory
may try to get address space from another RIR.
• RIR-shopping is viewed unfavorably in many policy
discussions, and many users of large address space,
such as ISPs with residential customers, have no
significant presence abroad. Transfer from other
RIRs are currently not allowed, but are under
discussion at ARIN as Proposal PP 119.
Endgame for IPs exhaustion
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By 2008, policy planning for the end-game and postexhaustion era.
Several proposals have been discussed to mitigate end game
shortages of IPv4 addresses.
Reclamation of unused IPv4 space
• IANA could potentially reclaim/reissue the underutilized ranges in smaller blocks, the transfer policy
from ARIN/RIPE/APNIC.
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Drawback: expensive and time-consuming to
renumber a large network since organizations will
likely object, with legal conflicts possible. Even if all
IPs were reclaimed, it would only postpone the date of
address exhaustion.
• IP blocks have been allocated to entities that no
longer exist or never used. No strict accounting of IP
allocations has been undertaken, need a big effort to
track down unused IPs, as many are only in use on
intranets.
Endgame for IPs exhaustion
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Reclamation of unused IPv4 space
• Some previously reserved blocks by IANA have
been added to available pool.
• proposals to use the class E network IPs,
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but many computer and router operating systems
and firmware can’t use these IPs.
For this reason, the proposals have sought not to
designate 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.
• Several organizations have returned large
blocks of IPs. Notably, Stanford University
relinquished their Class A IP block in 2000,
making 16 million IPs available. Other
organizations done so include the US DoD, BBN
Technologies, and Interop.
Endgame for IPs exhaustion
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ISP-wide network address translation (NAT)
• When ISPs implement NAT within their network,
they may allocate private addresses to customers
and need only one global scope address for a
potentially large group of customers.
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customers must use gateway for traffic to Internet.
successfully implemented in country like Russia, where
many broadband providers now use Carrier Grade NAT,
offer publicly routable IP at an additional cost
Research In Motion (RIM), BlackBerry maker, currently
routes all Blackberry data to central network operating
centers for encryption and decryption purposes;
reducing the number of public IPs assigned.
• However, ISP-wide NAT is not scalable, and limited
to the number of ports available (approximately
65000) in the Transport Layer protocols.
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NAT is not suitable for all applications
Endgame for IPs exhaustion
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Markets in IP addresses
• Create markets to buy and sell IPs, been proposed many
times as an efficient means of allocation.
• primary benefit is IPs would continue to be available.
major drawbacks prevent their implementation follow:
 only delay IP exhaustion for a relatively short time,
since the public Internet is still growing.
 The concept of legal IP "ownership" as property is
explicitly denied by ARIN/RIPE/ARIN NCC policy 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.
Endgame for IPs exhaustion
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Markets in IP addresses
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Ad-hoc IP trading would lead to fragmented patterns
of allocation, then vastly expand 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 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.
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The cost of changing from one set of IPs to another is
very high, reducing market liquidity. 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.
Endgame for IPs exhaustion
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IPv6
IPv4 address exhaustion
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The anticipated shortage has been the
driving factor in creating and adopting
several new technologies, including
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Classless Inter-Domain Routing (CIDR) in 1993,
network address translation (NAT),
Internet Protocol, IPv6, in 1998,
Use of private network addressing,
Name-based virtual hosting of web sites,
Tighter control by regional Internet registries on
allocating addresses to local Internet registries,
• Network renumbering and subnetting to reclaim
large blocks of address space allocated in the
early days of the Internet
IPv4 address exhaustion
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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.
IPv4 address exhaustion
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Mobile devices
• IPv4 is the de facto standard for networked digital
communication with low cost for embedding substantial
computing power into hand-held devices dropped.
• Mobile phones have become viable Internet hosts. New
specifications of 4G devices require IPv6 addressing.
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Always-on connections
• Throughout the 1990s, the predominant Internet access
was telephone modem dial-up. The rapid growth of the
dial-up networks increased address consumption rates,
although modem pools, and as a result, the pool of
assigned IP addresses, were shared amongst a larger
customer base.
• By 2007, broadband Internet access had exceed 50%
penetration in many markets. 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.
IPv4 address exhaustion
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Internet demographics
• For the developed world. In 1990, only a small fraction had
Internet connectivity. Just 15 years later, almost half of them
had persistent broadband connections. Internet users in
countries (China and India) are also driving address exhaustion.
Inefficient address use
• Organizations (1980s) were often allocated far more IPs than
needed, because initial method was inadequate to reflect
reasonable usage, e.g., large companies/universities were
assigned class A blocks, because class B block was too small.
• Organizations’s public IPs are not accessible outside LAN. From
a global address allocation viewpoint, this is inefficient, but
scenarios exist where this is preferred in organizational network
implementation strategies.
• Due to inefficiencies of subnetting, difficult to use all addresses
in a block. Host-density ratio (RFC 3194) a IP utilization metric.
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.
IPv4 Subnet Classes