3Com 5500G-EI Command Reference Guide - Page 58

58 CHAPTER 2: USING PORT COMMANDS View Ethernet Port View Parameter external: External loop test. internal: Internal loop test. Description Use the loopback command to configure the Ethernet port to perform the loopback test to check if the Ethernet port works normally. The loop test will finish automatically after being performed for a while. By default, the Ethernet port will not perform the loopback test. Example To perform the internal loop test for Ethernet1/0/1, enter the following: system-view System View: return to User View with Ctrl+Z. [SW5500]interface Gigabitethernet 1/0/1 [SW5500-GigabitEthernet1/0/1]loopback internal loopback-detection Syntax control enable loopback-detection control enable undo loopback-detection control enable View Ethernet Port View Parameter None Description Use the loopback-detection control enable command to enable loopback detection control function on a Trunk port or Hybrid port. Use the undo loopback-detection control enable command to disable loopback detection control function on a Trunk port or Hybrid port. This command controls the operating status of the port, when the loopback detection function is enabled and lookback is detected on a Trunk or Hybrid port. When this function is enabled and loopback is detected on a Trunk or Hybrid port, the system begins to control the operating status of the port. When this function is disabled and loopback is found, the system just reports a Trap message but has no control over the operating status of the Trunk or Hybrid port. By default, the loopback detection control function on Trunk or Hybrid ports is disabled. This command has no effect on Access ports.