A method in a communication system (20) including endpoints (24) that connect to one another using cable channels, includes injecting one or more test signals to a cable channel, which has first and second ends and is potentially connected to a first endpoint at the first end and to a second endpoint at the second end. One or more serial measurements are performed on the cable channel so as to sense the test signals. Based on the serial measurements, a decision is made as to which of the first and second endpoints are indeed connected to the cable channel.