ARIN Hosts 4-byte ASN Wiki

Posted: 22 June 2009

In response to a suggestion received through the ARIN Consultation and Suggestion Process (ACSP), ARIN has created a wiki at to focus on issues related to 4-byte Autonomous System Numbers (ASNs). This wiki provides a central repository for ongoing discussion and information exchange associated with 4-byte ASN topics and issues.

Ongoing Internet growth is rapidly depleting the existing pool of 2-byte ASNs (65,536 numbers in total). As a result, the IETF has approved the expansion of AS Numbers from 2-bytes to 4-bytes, to include over 4 billion ASNs. Following a globally coordinated policy, ARIN and the other Regional Internet Registries began assigning 4-byte ASNs by request in January 2007 and by default in January 2009. However, some routers do not support the use of these 4-byte ASNs.

ARIN has set up this wiki to help educate the community about 4-byte ASN operational issues, to help vendors understand how to provide 4-byte ASN support in their products and to help network operators find those products. A wide range of community stakeholders will be able to share and benefit from information contributed to ARIN looks forward to participation from everyone, including users, ISPs, and vendors, with interest in this topic.


Leslie Nobile
Director of Registration Services
American Registry for Internet Numbers (ARIN)