These pages and the links below are presented in the format of ARIN policy that was effective through October 14, 2004. This method of formatting was superseded by the format in the Number Resource Policy Manual (NRPM), which was published on October 15, 2004.
There are a limited number of available Autonomous System Numbers (AS Numbers), therefore, it is important to determine which sites require unique AS Numbers and which do not. Sites that do not require a unique AS Number should use one or more of the AS Numbers reserved for private use. Those numbers are: 64512 through 65535.
In order to be assigned an AS Number, each requesting organization must provide ARIN with verification that it has one of the following:
- A unique routing policy (its policy differs from its border gateway peers)
- A multi-homed site.
AS Numbers are issued based on current need. An organization should request an AS Number only when it is already multi-homed or will immediately become multi-homed. Details regarding requirements, fees, and applying for an AS Number can be found on the Guidelines for AS Numbers page.