Dear colleagues, As previously mentioned at RIPE 73, we are planning a project to clean up unused AS Numbers. You can find this presentation here: https://ripe73.ripe.net/archives/video/1456/ According to ripe-679, "Autonomous System (AS) Number Assignment Policies" if an organisation no longer uses as AS Number, it should be returned to the free pool so it can be reassigned: https://www.ripe.net/publications/docs/ripe-679 There are currently around 6,600 ASNs in our service region (held or sponsored by 2,682 LIRs) that are not being advertised in the routing system. This represents around 22% of the ~30,000 ASNs assigned by the RIPE NCC. There are a number of legitimate reasons why an ASN might not be advertised in the routing system. However, it is also possible that the holder doesn't exist anymore or the ASN is no longer needed. Not only should unused ASNs be returned, but it's important to clean up out of date registrations, which affect the quality of data in the RIPE Registry. Our Proposal We plan to email the LIR or sponsoring LIR for each unannounced ASN and ask if the resource is still needed. We will group together ASNs that are sponsored or held by the same LIR to minimise the number of emails. We will ask if the ASN is currently being used or if there are plans to start using the ASN in the coming three months. Organisations can always request a new ASN in the future if they need one. If we do not receive a reply or if the ASN will not be used within three months, we will start the process of returning the ASN to the free pool. The deregistration process will take three months, during which time the LIR can still indicate that the ASN is needed. If the ASN is still needed, the validity of the assignment (such as the multihoming requirement) will not be re-evaluated. We do not expect any significant cost or impact on other services, as most of this process will be automated and we will not need to re-evaluate the assignments. Contacting all relevant LIRs will take less than six months. Please review this proposal and send any comments or other feedback before Thursday 6 April to <address-policy-wg@ripe.net>. Regards, Laurens Hoogendoorn Registration Services RIPE NCC