SCION Registry: ISD and SCION AS assignments
SCION Isolation Domains (ISDs) are logical groups of SCION-enabled networks under a common jurisdiction and with a uniform trust environment. ISDs are identified with 16-bit numbers that must be globally unique.
SCION-enabled Autonomous Systems (SCION ASes) are identified with 48-bit numbers. Whilst these only need to be unique within an ISD, it is good practice to have globally unique identifiers so they may be used for multiple ISDs.
It is therefore necessary to coordinate the assignment of ISD and SCION AS numbers to entities in order to ensure global uniqueness; in a similar fashion to how Internet number resources are coordinated by Regional Internet Registries (e.g RIPE NCC). The role of Registration Authority is currently undertaken by Anapaya, but is planned to be transitioned to the SCION Association in 2026.
ISD number assignments
ISD numbers are represented in decimal notation.
| ISD | Size | Description |
|---|---|---|
| 0 | 1 | The wildcard ISD |
| 1 - 15 | 16 | Reserved for documentation and sample code (analogous to RFC 5398) |
| 16 - 63 | 48 | Private use (analogous to RFC 6996) Can be used for testing and private deployments |
| 64 - 4095 | 4032 | Public ISDs (currently assigned by Anapaya) |
| 4096 - 65535 | 61440 | Reserved for future use |
SCION AS number assignments
SCION AS numbers should be represented in hexadecimal notation, although numbers in the lowest 32-bit range (0-4294967295) may be represented in decimal notation.
| SCION AS | Size | Description |
|---|---|---|
| 0:0:0 | 1 | The wildcard AS |
| 0:0:1 - 0:ffff:ffff | 4294967295 | Public SCION ASes (currently assigned by Anapaya). Proposed to be used for mapping to Internet ASNs |
| 1:0:0 - 1:ffff:ffff | 4294967296 | Reserved for future use |
| 2:0:0 - 2:ffff:ffff | 4294967296 | Public SCION ASes (currently assigned by Anapaya) |
| 3:0:0 - feff:ffff:ffff | 280362580180992 | Reserved for future use |
| ff00:0:0 - ff00:0:ffff | 65536 | Reserved for documentation and sample code (analogous to RFC 5398) |
| ffaa:0:0 - ffaa:00ff:ffff | 16777216 | Reserved for private use (analogous to RFC 6996) Can be used for testing/private deployments |
| ffaa:0100:0 - ffff:ffff:fffe | 369350410239 | Reserved for future use |
| ffff:ffff:ffff | 1 | Reserved |