This document lists the assigned SCION protocol numbers.
SCION attempts to take the IANA’s assigned Internet protocol numbers into consideration. Widely used protocols will
have the same protocol number. SCION specific protocol numbers start at 200
which makes them very unlikely to clash.
The protocol numbers are used in the :ref:`SCION Header <header-specification>` to identify the next level protocol.
| Decimal | Keyword | Protocol |
|---|---|---|
| 0-5 | unassigned | |
| 6 | TCP/SCION | Transmission Control Protocol over SCION |
| 7-16 | unassigned | |
| 17 | UDP/SCION | User Datagram Protocol over SCION |
| 18-199 | unassigned | |
| 200 | HBH | :ref:`SCION Hop-by-Hop Options <hop-by-hop-options>` |
| 201 | E2E | :ref:`SCION End-to-End Options <end-to-end-options>` |
| 202 | SCMP | :ref:`SCION Control Message Protocol <scmp-specification>` |
| 203 | BFD/SCION | :ref:`BFD over SCION <bfd-specification>` |
| 204-252 | unassigned | |
| 253 | use for experimentation and testing | |
| 254 | use for experimentation and testing | |
| 255 | reserved |