This is not how USB Type C works. The cables are active (chipped), and the end devices have sense resistors. Each device can detect the presence and type of the

This is not how USB Type C works. The cables are active (chipped), and the end devices have sense resistors. Each device can detect the presence and type of the cable, as well as the presence and type of an end device and total cable orientation (swapped or not). This is all done before power is applied, as USB Type C is very explicit about not going hot (apart from a weak 5V V_conn for powering the cable). Also, QSFP is not a cable, but a pluggable spec. A QSFP module is active, but the fiber optic cable you connect to it to is dumb. Link detection there works by sensing beam power.