Global Policy for Allocation of ASN Blocks to Regional Internet Registries ratified by ICANN Board

(Ratified by ICANN Board on 31 July 2008)

(Obsoleted September 2010)


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 2009, allocations of 2-byte only and 4-byte only ASN blocks will be made separately and independent of each other[1]. This means until 31 December 2009, RIRs can receive two separate ASN blocks, one for 2-byte only ASNs and one for 4-byte only ASNs from the IANA under this policy. After this date, IANA and the RIRs will cease to make any distinction between 2-byte only and 4-byte only ASNs, and will operate ASN allocations from an undifferentiated 4-byte ASN allocation pool.

    1. Initial Allocations

Each new RIR will be allocated a new ASN block.

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

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

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 rate of assignment or allocation over the previous six months, unless the RIR specifically requests fewer blocks than those for which it qualifies.

    1. 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] Various regional 4-byte ASN policies, including:

Last modified on 24/09/2021