US Patent 7046928 Link discovery and verification using loss of light

Systems and methods for link discovery and verification that minimize the need for line termination resources to generate and interpret packets. To verify a link between two nodes, a first of the nodes toggles light or another signal output by one of its ports while the other node attempts to detect the toggling through its own ports. A link is therefore verified between the port that is toggling and the port that detects the toggling. This link verification technique does not require packet termination capability at either node. Furthermore, this link verification technique is very simple and may be executed very quickly even at nodes having a very large number of ports to which links maybe established.