Protocol version of the PRKI-RTR protocol operated.
- SNMP ID:
 - 2.93.7.1.6
 - Console path:
 - Setup > Routing-Protocols > RPKI > Caches
 - Possible values:
 - Null
 - Protocol version 0 is used to communicate with the cache.
 - One
 - Protocol version 1 is used to communicate with the cache.
 - Fallback
 - Communication with the cache starts with version 1 and falls back to version 0 if necessary.