Policy 2003-12: IANA to RIR Allocation of IPv4 Address Space

Status: Adopted - NRPM Section 10

Tracking Information

Discussion Tracking

Mailing List:

Formal introduction on PPML on 12 September 2003

Final version of proposal posted to PPML on 18 November 2003. Public Policy Mailing List

ARIN Public Policy Meeting:


ARIN Advisory Council:

23 October 2003
18 December 2003

ARIN Board of Trustees:

22 December 2003



8 April 2005


IANA to RIR Allocation of IPv4 Address Space

This document describes the policies governing the allocation of IPv4 address space from the IANA to the Regional Internet Registries (RIRs). This document does not stipulate performance requirements in the provision of services by IANA to an RIR in accordance with these policies. Such requirements should be specified by appropriate agreements among the RIRs and ICANN.

1. Allocation Principles

  • The IANA will allocate IPv4 address space to the RIRs in /8 units.
  • The IANA will allocate sufficient IPv4 address space to the RIRs to support their registration needs for at least an 18 month period.
  • The IANA will allow for the RIRs to apply their own respective chosen allocation and reservation strategies in order to ensure the efficiency and efficacy of their work.

2. Initial Allocations

Each new RIR shall, at the moment of recognition, be allocated a new /8 by the IANA. This allocation will be made regardless of the newly formed RIR’s projected utilization figures and shall be independent of the IPv4 address space that may have been transferred to the new RIR by the already existing RIRs as part of the formal transition process.

3. Additional Allocations

A RIR is eligible to receive additional IPv4 address space from the IANA when either of the following conditions are met.

  • The RIR’s AVAILABLE SPACE of IPv4 addresses is less than 50% of a /8 block.
  • The RIR’s AVAILABLE SPACE of IPv4 addresses is less than its established NECESSARY SPACE for the following 9 months.

In either case, IANA shall make a single allocation of a whole number of /8 blocks, sufficient to satisfy the established NECESSARY SPACE of the RIR for an 18 month period.

3.1 Calculation of AVAILABLE SPACE

The AVAILABLE SPACE of IPv4 addresses of a RIR shall be determined as follows:


FRAGMENTED SPACE is determined as the total amount of available blocks smaller than the RIR’s minimum allocation size within the RIR’s currently available stock.

3.2 Calculation of NECESSARY SPACE

If the applying Regional Internet Registry does not establish any special needs for the period concerned, NECESSARY SPACE shall be determined as follows:


If the applying RIR anticipates that due to certain special needs the rate of allocation for the period concerned will be greater than the previous 6 months, it may determine its NECESSARY SPACE as follows:

  1. Calculate NECESSARY SPACE as its total needs for that period according to its projection and based on the special facts that justify these needs.
  2. Submit a clear and detailed justification of the above mentioned projection (Item A).

If the justification is based on the allocation tendency prepared by the Regional Internet Registry, data explaining said tendency must be enclosed.

If the justification is based on the application of one or more of the Regional Internet Registry's new allocation policies, an impact analysis of the new policy/policies must be enclosed.

If the justification is based on external factors such as new infrastructure, new services within the region, technological advances or legal issues, the corresponding analysis must be enclosed together with references to information sources that will allow verification of the data.

If IANA does not have elements that clearly question the Regional Internet Registry's projection, the special needs projected for the following 18 months, indicated in Item A above, shall be considered valid.

4. Announcement of IANA Allocations

When address space is allocated to a RIR, the IANA will send a detailed announcement to the receiving RIR. The IANA will also make announcements to all other RIRs, informing them of the recent allocation. The RIRs will coordinate announcements to their respective membership lists and any other lists they deem necessary.

The IANA will make appropriate modifications to the “Internet Protocol V4 Address Space” page of the IANA website and may make announcements to its own appropriate announcement lists. The IANA announcements will be limited to which address ranges, the time of allocation and to which Registry they have been allocated.