An optical time-domain reflectometer, OTDR, device comprising: a laser source to emit a laser beam into a device under test, DUT; a connection port to connect the OTDR device 100 to a first end of the DUT, wherein the OTDR device is designated a first OTDR device; and a sensor display generator, executed by at least one hardware processor of the first OTDR device, to: determine, based on the laser beam, a length of the DUT; wherein the at least one hardware processor of the first OTDR device is configured to: receive, from a second OTDR device connectable to a second opposite end of the DUT, and over the DUT, OTDR information by the second OTDR device, wherein the OTDR information includes an identification of optical events with respect to the DUT in a direction from the second OTDR device towards the first OTDR device; ascertain, based on acquisition by the first OTDR device, further OTDR information that includes an identification of optical events with respect to the DUT in a direction from the first OTDR device towards the second OTDR device; and generate, based on the determined length of the DUT, the OTDR information received, over the DUT, by the first OTDR device, and the further OTDR information acquired by the first OTDR device, a bi-directional combined schematic display that includes relevant optical events with respect to the DUT. a laser source to emit a laser beam into a device under test, DUT; a connection port to connect the OTDR device 100 to a first end of the DUT, wherein the OTDR device is designated a first OTDR device; and a sensor display generator, executed by at least one hardware processor of the first OTDR device, to: determine, based on the laser beam, a length of the DUT; wherein the at least one hardware processor of the first OTDR device is configured to: receive, from a second OTDR device connectable to a second opposite end of the DUT, and over the DUT, OTDR information by the second OTDR device, wherein the OTDR information includes an identification of optical events with respect to the DUT in a direction from the second OTDR device towards the first OTDR device; ascertain, based on acquisition by the first OTDR device, further OTDR information that includes an identification of optical events with respect to the DUT in a direction from the first OTDR device towards the second OTDR device; and generate, based on the determined length of the DUT, the OTDR information received, over the DUT, by the first OTDR device, and the further OTDR information acquired by the first OTDR device, a bi-directional combined schematic display that includes relevant optical events with respect to the DUT. receive, from a second OTDR device connectable to a second opposite end of the DUT, and over the DUT, OTDR information by the second OTDR device, wherein the OTDR information includes an identification of optical events with respect to the DUT in a direction from the second OTDR device towards the first OTDR device; ascertain, based on acquisition by the first OTDR device, further OTDR information that includes an identification of optical events with respect to the DUT in a direction from the first OTDR device towards the second OTDR device; and generate, based on the determined length of the DUT, the OTDR information received, over the DUT, by the first OTDR device, and the further OTDR information acquired by the first OTDR device, a bi-directional combined schematic display that includes relevant optical events with respect to the DUT. the determined length of the DUT, the OTDR information received, over the DUT, by the first OTDR device, and the further OTDR information acquired by the first OTDR device, a bi-directional combined schematic display that includes relevant optical events with respect to the DUT.