Abstract: Techniques to ascertain physical cabling connections of electronic systems are provided for situations where there are numerous systems interconnected by a very large number of electrical or optical cables. A cable identifying code is inserted into a message sent from a local endpoint system to remote endpoint system over the identified cable. Each intermediate system that is in the interconnection path between the two endpoint systems of interest appends its code for the cable connected to the I/O port from which the message will egress that system and be sent to the next system along the path. The remote endpoint system receives the message which now contains codes for all the cables transited along the path, extract the codes, and thereby determines the exact cabling used in the interconnection of the two endpoint systems.