Glossary: ASN (Autonomous System Number)
An ASN is a unique identifier allocated to autonomous systems for use in BGP routing.
Understanding ASNs
ASNs are crucial for internet routing. They enable the Border Gateway Protocol (BGP) to make routing decisions and ensure data packets find the best path across the global internet.
ASN Allocation
- Assigned by Regional Internet Registries (RIRs)
- 16-bit ASNs: 1 to 65,534 (mostly exhausted)
- 32-bit ASNs: 65,536 to 4,294,967,295
- Private ASNs: 64,512 to 65,534 and 4,200,000,000 to 4,294,967,295
Who Needs an ASN?
- Internet Service Providers (ISPs)
- Large enterprises with multiple internet connections
- Content Delivery Networks (CDNs)
- Cloud service providers
- Data centers