6.1.3. CN5000 Port Numbers
The CN5000 SuperNIC has two ports, but only the second port is active when a standard QSFP cable is used. This means tools like ibstat will show only the second port as Active, and the first port is Down. This behavior is expected. The OPX Provider will automatically select the second port when running MPI jobs. However, care must be taken when running IPoIB or verbs applications that the second port is selected.