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 . <EOS>