FAQ: 32-bit ASN

Show or Hide answer What is a 32-bit ASN?

32-bit ASN stands for 32-bit Autonomous System Number.

Show or Hide answer Why have 32-bit ASNs been introduced?

With 16-bit AS Numbers, around 65,000 unique numbers are possible. Around 73% of these numbers have already been assigned. Studies have shown that with the present assignment rate, the supply of 16-bit ASNs will be exhausted between 2010 and 2015. The introduction of 32-bit ASNs increases the supply of AS Numbers to four billion.

Show or Hide answer When can I request a 32-bit ASN?

You can request one now. If you do not specifically ask for a 32-bit ASN, you will receive a 16-bit ASN. However, as of 1 January, 2009, all assignments will be 32-bit ASN by default, unless you specifically ask for a 16-bit ASN. From 1 January 2010, there will be no differentiation between the two varieties and the RIPE NCC will assign from a single pool.

Show or Hide answer I already have an AS Number. Do I need to apply for a new one?

No. 16-bit ASNs and 32-bit ASNs are interoperable. You do not have to renumber. If you do not plan to expand your network it is sufficient to check that your tools still work when you enter a 32-bit ASN.

Show or Hide answer Should I request a 16-bit ASN or a 32-bit ASN?

If you are using the latest equipment and software and your upstream provider supports 32-bit ASNs, apply for a 32-bit ASN. If you are using older equipment and software, apply for a 16-bit ASN.

Show or Hide answer How can I get a 32-bit ASN?

You should fill in the Resource Request Form (requires authentication).

You will receive a 32-bit ASN by default, unless you specifically request a 16-bit ASN and explain why a 32-bit ASN cannot be used.

Here you can see the information that will be required for your request.

Show or Hide answer How do I apply for a temporary 32-bit ASN to test my network?

It is possible to request temporary resources for deployment for a specific time-limited purpose. For details, see the FAQ: Temporary Internet Number Assignment.

Show or Hide answer Will the assignment policy change?

No, the criteria for assignment of an ASN will not change.

See RIPE Policy Proposal 2005-12 for more details.

Show or Hide answer Are 32-bit ASNs only available in the RIPE NCC service region?

No. All of the Regional Internet Registries (RIRs) can assign them.

Show or Hide answer What is the format of a 32-bit ASN?

As of 25 March 2009, RIPE NCC services reference AS Numbers in ASPLAIN format. This is in line with RFC 5396, published in December 2008.

Show or Hide answer Where can I find out more about 32-bit ASNs?

The following Internet Engineering Task Force (IETF) documents offer more information about 32-bit ASNs:

BGP Support for Four-octet AS Number Space (RFC 4893)
This document describes the changes to the BGP protocol and the 16-bit ASN to 32-bit ASN transition mechanism.

A list of operating system versions compatible with 32-bit ASNs is available at: