This read-write value reports/sets whether this physical port's role in its redundant circuit is notUsed(1), primary(2), or backup(3), the port-table view of the same role tracked by rptrRedundPortType in the circuit table. Admins use it to designate which physical port should be the active path and which should stand by, or to manually force a failover for testing. Manually flipping this from backup to primary is one way to force traffic onto a specific port during a planned test.