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ACSP Suggestion 2017.14: Provide Statistics About the Size of Available 2-byte and 4-byte ASNs


Jason Schiller
Submitted On:
25 July 2017

Description: Please provide statistics about the size of available 2-byte and 4-byte ASN that ARIN is holding. Please also provide the number of ASNs that are in an otherwise "pending" state and when they are anticipated to become available.

Value to Community: This is low priority until the 2-byte ASN pool is in danger of depletion.

Would be good to know how big the 2-byte AS cushion is as we get closer to depletion of 2-byte ASNs.

Timeframe: Not specified

7 August 2017

Tracking Information

ARIN Comment

07 August 2017

Thank you for your suggestion, numbered 2017.14 upon confirmed receipt, to provide statistics about the size of ARIN's available 2-byte and 4-byte AS Number pools.

As guided by previous policy in the Number Resource Policy Manual (NRPM), ARIN no longer makes a distinction between 2-byte only and 4-byte only AS Numbers, but does recognize identification of the "classic 2-byte range" of AS Numbers sometimes referred to by customers during the request process. For the purposes of this ACSP response, AS Numbers from the classic 2-byte pool will be referred to as "2-byte" and those from the non-classic 2-byte pool will be referred to as "4-byte".

At the time of writing this ACSP response, ARIN has 303 2-byte AS Numbers along with 677 4-byte AS Numbers in our active inventory to be issued. Newly approved requests receive the lowest AS Number in our active inventory at the time of issuance. If we happen to have a 2-byte AS Number in inventory at that time, it will be issued. In cases where there is no 2-byte AS Number in active inventory at the time of issuance, the next 4-byte AS Number in the inventory is issued.

ARIN regularly receives AS Numbers back into our inventory either through returns or revocation due to non-payment of registration fees in accordance with the ARIN Registration Services Agreement. When we receive these returns or make these revocations, we hold the subject AS Numbers outside of the active inventory for a period of time to help prevent potential disputes for new registrants who might receive these recycled AS Numbers. At certain times of the year, ARIN registration staff conducts a review of these held AS Numbers for re-introduction into our active inventory. When that happens, recycled AS Numbers from the 2-byte range are sometimes included in the batch that gets added to our active inventory.

We still occasionally receive a request from a new AS Number registrant who received a 4-byte AS Number during the request process to have that exchanged for a 2-byte AS Number. We accommodate those requests when they are made and conduct a review of our inactive (held) inventory to identify a suitable 2-byte AS Number for the customer. Over the last two years, requests to exchange a 2-byte for a 4-byte AS Number have decreased in frequency. In the last year, we averaged fewer than two requests of this type per month.

At the time of writing this ACSP response, ARIN's AS Number inventory consisted of:

  • Active Inventory (ready to be issued)
    • 2-byte: 303
    • 4-byte: 677
  • Inactive Inventory (held returns or revocations)
    • 2-byte: 1,019
    • 4-byte: 44

Over time, the AS Numbers from our inactive inventory will continue to be added to our active inventory. At the same time, however, we will continue to reclaim AS Numbers through voluntary customer returns and ARIN revocations due to non-payment of registration fees.

Going forward, ARIN staff will provide a biannual report on the status of both our active and inactive AS Number inventories, including data separation for 2-byte and 4-byte ranges. This information will be featured in the Registration Services Department report presented at the ARIN meetings in April and October of each year and published along with the associated meeting reports on the ARIN website.

Thank you for participating in the ARIN Consultation and Suggestion Process. We are closing your suggestion with the commitment to continue providing this information on a biannual basis going forward.

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