| 摘要 |
PROBLEM TO BE SOLVED: To provide a loopback test method that can be executed online. SOLUTION: In a system that is provided with computers 11, 12,..., each having a loopback test function and a line concentration device (HUB) 31 having ports 1, 2, etc., connected to the computers through a twisted pair cable 21 having a transmission line 211 and a reception line 212, each port has an SW1 that connects the transmission line and the reception line, and a communication control section 3111 that issues a test request in the absence of transmission reception data from a computer connected to itself and other ports, the SW1 is connected when receiving an ACK from the computer to conduct a test from the computer. The HUB 31 has a buffer that temporarily stores data received from the other port during the test. |
