HP 6125G HP 6125G & 6125G/XG Blade Switches Layer 2 - LAN Switching Co - Page 31

Description Use loopback to enable loopback testing on an Ethernet interface. Use undo loopback to disable loopback testing on an Ethernet interface. By default, loopback testing is disabled on Ethernet interfaces. Enable loopback testing for troubleshooting purposes, such as identifying an Ethernet problem. NOTE: During loopback testing, the speed, duplex, mdi, and shutdown commands are not available. In addition, the port is operating in full duplex mode, regardless of its duplex configuration. After loopback testing is disabled, the duplex configuration of the port is restored. Examples # Enable internal loopback testing on GigabitEthernet 1/0/1. system-view [Sysname] interface gigabitethernet 1/0/1 [Sysname-GigabitEthernet1/0/1] loopback internal loopback-detection action Syntax loopback-detection action { no-learning | semi-block | shutdown } View undo loopback-detection action Ethernet interface view Default level 2: System level Parameters no-learning: Disables MAC address learning on the interface. semi-block: Blocks all packets but STP BPDUs, and disables MAC address learning on the interface. shutdown: Shuts down the Ethernet interface. To bring up the interface again, use the undo shutdown command. Description Use loopback-detection action to configure the action for loop protection on Ethernet interfaces. Use undo loopback-detection action to restore the default. By default, a looped interface does not receive or send packets; the system generates traps and log messages, and deletes the MAC address table entries of the looped interface. When you change the link type of an Ethernet interface by using the port link-type command, the switch removes the protective action configured on the interface. For more information about the port link-type command, see "VLAN configuration commands." Examples # Configure the access port GigabitEthernet 1/0/1 to shut down when a loop is detected. 23