UDLD Configuration Commands Table of Contents Table of Contents Chapter 1 UDLD Configuration Commands.................................................................................................1 1.1 UDLD Configuration Commands.....................................................................................................1 1.1.1 udld enable..............................................................................................................................1 1.1.2 udld aggressive...................................................................................................................... 2 1.1.3 udld port...................................................................................................................................3 1.1.4 udld port aggressive.............................................................................................................. 4 1.1.5 udld message......................................................................................................................... 4 1.1.6 udld reset.................................................................................................................................5 1.1.7 show udld................................................................................................................................ 6 - I - UDLD Configuration Commands Chapter 1 UDLD Configuration Commands 1.1 UDLD Configuration Commands The UDLD configuration commands are listed below:  udld enable  udld aggressive  udld port  udld port aggressive  udld message  udld reset  show udld 1.1.1 udld enable Syntax udld enable It is used to enable UDLD globally in normal mode. no udld enable It is used to disable UDLD globally in normal mode. Parameter None Default settings None Usage explanation This command is used to enable UDLD on all interfaces in normal mode. In normal mode, if UDLD determines that the connection is gone, UDLD will set the state of the - 1 - UDLD Configuration Commands port to undetermined, not to down. If UDLD maintains it is a bidirectional link, the port will be set to bidirectional. Command mode Global Example The following example shows how to enable UDLD in normal mode: Switch_config#udld enable 1.1.2 udld aggressive Syntax udld aggressive It is used to enable UDLD globally in aggressive mode. no udld aggressive It is used to disable UDLD globally in aggressive mode. Parameter None Default Settings None Usage explanation This command is used to enable UDLD on all interfaces in aggressive mode. In aggressive mode, if UDLD determines that the link is gone and the link cannot be reconnected, it is thought that interrupted communication is a severe network problem and UDLD will set the state of the protocol to down and the port is in down state. If UDLD maintains it is a bidirectional link, the port will be set to bidirectional. Command mode Global - 2 - UDLD Configuration Commands Example The following example shows how to enable UDLD in aggressive mode: Switch_config#udld aggressive 1.1.3 udld port Syntax udld port This command is used to enable UDLD on a port in normal mode. no udld port This command is used to disable UDLD on a port in normal mode. Parameter None Default Settings None Usage explanation This command is used to enable UDLD on the local port in normal mode. In normal mode, if UDLD determines that the connection is gone, UDLD will set the state of the port to undetermined, not to down. If UDLD maintains it is a bidirectional link, the port will be set to bidirectional. Command mode Interface configuration mode Example The following example shows how to enable UDLD in normal mode: Switch_config_f0/1#udld port - 3 - UDLD Configuration Commands 1.1.4 udld port aggressive Syntax udld port aggressive It is used to enable UDLD on the local interface in aggressive mode. no udld port aggressive It is used to disable UDLD on the local interface in aggressive mode. Parameter None Default Settings None Usage explanation This command is used to enable UDLD on the local interface in aggressive mode. In aggressive mode, if UDLD determines that the link is gone and the link cannot be reconnected, it is thought that interrupted communication is a severe network problem and UDLD will set the state of the protocol to down and the port is in down state. If UDLD maintains it is a bidirectional link, the port will be set to bidirectional. Command mode Interface configuration mode Example The following example shows how to enable UDLD in aggressive mode: Switch_config_f0/1#udld port aggressive 1.1.5 udld message Syntax udld message time It is used to set the message interval in aggressive mode. - 4 - UDLD Configuration Commands no udld message It is to resume the default message interval in aggressive mode. Parameter Parameter Explanation time Stands for the message interval in aggressive mode. It ranges between 7 and 90 seconds. Default Settings 15s Usage explanation This command is used to set the message interval in aggressive mode. After the message is set, you need to reset the aggressive mode and then the new message interval takes effect. Command mode Global Example The following example shows how to set the message interval to 7 seconds in aggressive mode, which takes effect after the aggressive mode is restarted. Switch_config#udld message 7 1.1.6 udld reset Syntax udld reset It is used to reset the interface which is down by UDLD to up. Parameter None - 5 - UDLD Configuration Commands Default Settings None Usage explanation This command is used to reset the interface which is down by UDLD to up. Command mode EXEC Example The following example shows how to restart the interface which is closed by UDLD. Switch#udld reset 1 ports shutdown by UDLD were reset. %%UDLD-2-UDLD_PORT_RESET: UDLD reset interface FastEthernet0/1. %%PM-4-ERR_RECOVER: Attempting to recover from udld err-disable state on FastEthernet0/1. 1.1.7 show udld Syntax show udld [interface ] It is used to display the information about UDLD running. Parameter Parameter Explanation interface Shows the running of the UDLD module on a specific interface. Default Settings None Usage explanation This command can display the running of the UDLD module. When the interface parameter is not entered, the information about the running of all UDLDs on all interfaces will be displayed; when the interface parameter is entered, only the running of the UDLD on this interface will be displayed. - 6 - UDLD Configuration Commands Command mode EXEC / global Example The following commands will display the running states of UDLD modules on all interfaces. Switch_config#show udld Interface FastEthernet0/1 --- Port enable administrative configuration setting: Enabled Port enable operational state: Enabled Current bidirectional state: Unknown Current operational state: Link down Message interval: 15 Time out interval: 1 No neighbor cache information stored Interface FastEthernet0/2 --- Port enable administrative configuration setting: Enabled Port enable operational state: Enabled Current bidirectional state: Unknown Current operational state: Link down Message interval: 15 Time out interval: 1 No neighbor cache information stored Interface FastEthernet0/3 --- Port enable administrative configuration setting: Enabled Port enable operational state: Enabled Current bidirectional state: Unknown Current operational state: Link down Message interval: 15 Time out interval: 1 No neighbor cache information stored .... .... .... The following commands will display the running state of the UDLD module on the f0/1 interface. Switch_config#show udld interface f0/1 - 7 - UDLD Configuration Commands Interface FastEthernet0/1 --- Port enable administrative configuration setting: Enabled Port enable operational state: Enabled Current bidirectional state: Unknown Current operational state: Link down Message interval: 15 Time out interval: 1 No neighbor cache information stored Switch_config# - 8 -