1. 4-Byte AS number registry Policy Proposal [LACNIC Proposal ]
Geoff Huston
APNIC
25 May 2006
The references to the LACNIC Policy Proposal number and the text of the proposal are included here.

2. 32-bit AS number registry
A policy proposal for LACNIC to assist in the general transition to the use of 32 bit AS numbers
Essential attributes of this policy:
Ease of transitional arrangements
Predictability of registry actions
Clear dates in terms of registry actions
As the Internet continues to grow the ability to deploy new versions of infrastructure protocols gets harder and more consideration regarding pre-deployment actions needs to be taken into account. This policy proposal attempts to create some predictable and clear dates for the transition from 16 bit to 32 bit AS numbers. This is to allow software vendors, network operators, trainers, documenters, users and of course registries sufficient time to understand what aspects of their environment needs to change in order to support 32 bit AS numbers.

3. Why Now and not Later?
Triggered by the completion of the IETF 4-Byte AS Number proposal* to Proposed Standard publication and predictions of effective exhaustion of the 16-bit AS number pool**
Proposes to provide a 3 year period of transition to support piecemeal testing and deployment of revised BGP versions that support 32-bit AS numbers
This proposal is being introduced now to allow a minimum of a three year period to achieve an orderly transition to the use of 32 bit AS numbers. This synchronises with a forecast of 16 bit AS number exhaustion of October 2010 ( It also coincodes with the completion of the definitional work on the IETF standards to support 32 bit AS Numbers.
* draft-ietf-idr-as4bytes-12.txt
** variously estimated to occur between 2010 and 2012

4. Assumptions
The IANA actions as specified in the IETF 4-Byte AS Number document will be completed by 1 January 2007
LACNIC will have ensured that its data systems are 32-bit ‘clean’ for the AS Number registry by 1 January 2007
The asusmptions behind this policy proposal are listed here.

5. The ASN Registry Proposal
Proposed AS assignment transition in 3 phases:
Commencing on 1 January 2007 the registry will process applications for 32-bit only AS numbers1 upon specific request. 16-bit only AS numbers2 will be assigned by default
Commencing on 1 January 2009 the registry will assign 32-bit only AS numbers1 by default. 16-bit only AS numbers will be assigned upon specific request2
Commencing on 1 January 2010 the registry will assign from the extended AS number space3
This is the text of the proposal. Note that a requestor does not need to justify why they require a 16 bit or a 32 bit AS numbewr – they simply have to ask for one or the other. Also note that as of 1 January 2010 there will be no further distinction drawn between the two number pools – they will all just be considered as 32 bit AS Numbers.
1 – AS numbers in the range 65,536 – 4,294,967,295
2 – AS numbers in the range 0 – 65,535
3 – AS numbers in the range 0 - 4,294,967,295

6. This proposal does NOT:
Introduce any extensions to the private AS number space
Define any documentation-use AS numbers
Advocate the continuation of any 2-byte AS number ‘legacy pool’ beyond 1 January 2010
Create policies that extend beyond 1 January 2010
Require LACNIC to undertake any RIR-coordinated actions
Define a different AS number allocation practice for registry operations
i.e. there are no other changes to the eligibility or conditions for AS number assignment in this policy.