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Internet Assigned Numbers Authority (IANA) Policy for Allocation of ASN Blocks to Regional Internet Registries

Publication date:
09 Sep 2010
  • Global RIRs
PDF (64.1 KB)


This document describes the policy governing the allocation of Autonomous System Numbers (ASNs) from the IANA to the Regional Internet Registries (RIRs).

This policy document does not stipulate performance requirements in the provision of services by the IANA to an RIR. Such requirements will be specified by appropriate agreements between ICANN and the Number Resource Organization (NRO).

1. Allocation Principles

IANA allocates ASNs to RIRs in blocks of 1024 ASNs. In this document the term "ASN block" refers to a set of 1024 ASNs. Until 31 December 2010, allocations of 16-bit and 32-bit only ASN blocks will be made separately and independent of each other[1].

This means until 31 December 2010, RIRs can receive two separate ASN blocks, one for 16-bit ASNs and one for 32-bit only ASNs from the IANA under this policy. After this date, IANA and the RIRs will cease to make any distinction between 16-bit and 32-bit only ASNs, and will operate ASN allocations from an undifferentiated 32-bit ASN allocation pool.

2. Initial Allocations

Each new RIR will be allocated a new ASN block.

3. Additional Allocations

An RIR is eligible to receive (an) additional ASN block(s) from the IANA if one of the following conditions is met:

  1. The RIR has assigned/allocated 80% of the previously received ASN block, or
  2. The number of free ASNs currently held by the RIR is less than two months need. This projection is based on the monthly average number of ASNs assigned/allocated by the RIR over the previous six months.

An RIR will be allocated as many ASN blocks as are needed to support their registration needs for the next 12 months, based on their average assignment/allocation rate over the previous six months, unless the RIR specifically requests fewer blocks than it qualifies for.

4. Announcement of IANA Allocations

The IANA, the NRO and the RIRs will make announcements and update their respective websites/databases when an allocation is made by the IANA to an RIR. ICANN and the NRO will establish administrative procedures to manage this process.

1. 1.16-bit ASNs are the AS Numbers in the range: 0 - 65535
32-bit only ASNs are the AS Numbers in the range: 65536 - 4294967295
32-bit ASNs are the AS Numbers in the range: 0 - 4294967295