A verification environment enables verification of runtime switch-over—i.e., a switch-over without restarting the device under test—between multiple I/O protocols that share a same physical interface. The device under test can be a switch unit having multiple logical protocol processing units and a logical protocol multiplexor. The verification environment includes a switch-over detector which monitors the state of the device under test, and a switch-over controller that controls the switch-over sequence by pausing and re-starting traffic on all or specific protocol drivers of the verification environment.