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Reassigning Referenced AS Numbers

The RIPE NCC has a large supply of returned 16 and 32-bit Autonomous System (AS) Numbers that are referenced in RIPE Database objects. With the global supply of 16-bit AS Numbers becoming exhausted, there is a clear need for these resources from some operators.

What Are These References?

These AS Numbers are referenced in a number of objects - mostly other AS Number objects in the policy statements of the "import:" and "export:" attributes and various set objects. We have also found a handful of route objects which don't originate from these returned AS Numbers but reference them in other attributes. Detailed analysis shows that around 4,000 objects are referencing these 1,900 AS Numbers.

In accordance with a decision by the RIPE Address Policy Working Group, the RIPE NCC assigns 32-bit AS Numbers by default, unless a 16-bit ASN is specifically requested. Given the current rate of assignment, we expect to run out of available unreferenced 16-bit ASNs in the near future.

What is next?

After receiving feedback from the RIPE community, we will start reassigning referenced ASNs once the pool of unreferenced 16-bit ASNs has been exhausted. The RIPE NCC will only issue 16-bit ASNs that have been returned or reclaimed and are not globally routed.

The RIPE NCC will send one email to the maintainer and contacts for the RIPE Database objects that reference returned AS Numbers, asking for these references to be removed.

More information on how the RIPE NCC reuses returned Internet number resources.