staLoopbackDetectionPortIfIndex — Multiple manufacturers; see the original MIB MIB copies (LibreNMS/Observium Community), Edgecore official enterprise switch MIBs, Edgecore MIB copies (Observium Community)
The port and the trunk interfaces of the portTable. The interface identified by a particular value of this index is the same interface as identified by the same value of ifIndex in the IF-MIB.