There are two types of BGP Autonomous system numbers: Private and Public.
Various routing protocols use Autonomous System (AS) Numbers. IANA allocates AS Numbers to Regional Internet Registries (RIRs). The five RIRs are:
- AFRINIC
- APNIC
- ARIN
- LACNIC
- RIPE_NCC
AS Numbers can be obtained from the registry in your region.
16-bit ASN
| Number | Assignment |
| 0 | Reserved |
| 1-48127 | Assigned |
| 48128-54271 | Unassigned |
| 54272-64511 | Reserved by IANA |
| 64512-65534 | Free for internal use (private range) |
| 65535 | Reserved |
32-bit ASN
| Number | Assignment |
| 0.0-0.65535 | Old 16-bit ASNs |
| 1.0-1.65535 | reserved |
| 2.0-2.1023 | Allocated to APNIC |
| 2.1024-2.65535 | Unassigned |
| 3.0-3.1023 | Allocated to RIPE NCC |
| 3.1024-3.65535 | Unassigned |
| 4.0-4.1023 | Allocated to LACNIC |
| 4.1024-4.65535 | Unallocated |
| 5.0-5.1023 | Allocated to AfriNIC |
| 5.1024-5.65535 | Unallocated |
| 6.0-6.1023 | Allocated to ARIN |
| 6.1024-65535.65534 | Unallocated |
| 65535.65535 | reserved |
