[arin-ppml] ARIN-2011-5: Shared Transition Space for IPv4 Address Extension - Last Call

ARIN info at arin.net
Mon Apr 18 15:06:51 EDT 2011

The ARIN Advisory Council (AC) met on 13 April 2011 and decided to
send the following draft policy to last call:

   ARIN-2011-5: Shared Transition Space for IPv4 Address Extension

Feedback is encouraged during the last call period. All comments should
be provided to the Public Policy Mailing List. Last call for 2011-5 will
expire on 2 May 2011. After last call the AC will conduct their last
call review.

The draft policy text is below and available at:

The ARIN Policy Development Process is available at:


Communications and Member Services
American Registry for Internet Numbers (ARIN)

## * ##

Draft Policy ARIN-2011-5
Shared Transition Space for IPv4 Address Extension

Date: 20 January 2011

Policy statement:

Updates 4.10 of the NRPM:
A second contiguous /10 IPv4 block will be reserved to facilitate IPv4
address extension. This block will not be allocated or assigned to any
single organization, but is to be shared by Service Providers for
internal use for IPv4 address extension deployments until connected
networks fully support IPv6. Examples of such needs include: IPv4
addresses between home gateways and NAT444 translators.


The Internet community is rapidly consuming the remaining supply of
unallocated IPv4 addresses. During the transition period to IPv6, it is
imperative that Service Providers maintain IPv4 service for devices and
networks that are currently incapable of upgrading to IPv6.
Consumers must be able to reach the largely IPv4 Internet after
exhaustion. Without a means to share addresses, people or organizations
who gain Internet access for the first time, or those who switch
providers, or move to another area, will be unable to reach the IPv4

Further, many CPE router devices used to provide residential or
small-medium business services have been optimized for IPv4 operation,
and typically require replacement in order to fully support the
transition to IPv6 (either natively or via one of many transition
technologies). In addition, various consumer devices including
IP-enabled televisions, gaming consoles, medical and family monitoring
devices, etc. are IPv4-only, and cannot be upgraded. While these will
eventually be replaced with dual-stack or IPv6 capable devices, this
transition will take many years. As these are typically consumer-owned
devices, service providers do not have control over the speed of their
replacement cycle. However, consumers have an expectation that they
will continue to receive IPv4 service, and that such devices will
continue to have IPv4 Internet connectivity after the IPv4 pool is
exhausted, even if the customer contracts for new service with a new

Until such customers replace their Home Gateways and all IPv4-only
devices with IPv6-capable devices, Service Providers will be required to
continue to offer IPv4 services through the use of an IPv4 address
sharing technology such as NAT444. A recent study showed that there is
no part of RFC1918 space which would not overlap with some IPv4
gateways, and therefore to prevent address conflicts, new address space
is needed.

Service providers are currently presented with three options for
obtaining sufficient IPv4 address space for NAT444/IPv4 extension
deployments: (1) Request allocations under the NRPM; (2) share address
space with other providers (this proposal); or (3) use address space
allocated to another entity (i.e. ‘squat’). Of the three options,
option 2 (this proposal) is preferable, as it will minimize the number
of addresses used for IPv4 extension deployments while preserving the
authority of IANA and RIRs.

Timetable for implementation: immediately

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