Extracted from CCO
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gnore-dcd
To configure the serial interface to monitor the Data Set Ready (DSR) signal instead of the Data Carrier Detect (DCD) signal as the line up/down indicator, use the ignore-dcd command in interface configuration mode. To restore the default, use the no form of this command.
ignore-dcd
no ignore-dcd
Syntax Description
This command has no arguments or keywords.
Defaults
The serial interface, operating in DTE mode, monitors the DCD signal as the line up/down indicator.
Command Modes
Interface configuration
Command History
Release
Modification
11.0
This command was introduced.
Usage Guidelines
This command applies to Quad Serial NIM interfaces on the Cisco 4000 series routers and Hitachi-based serial interfaces on the Cisco 2500 and Cisco 3000 series routers.
Serial Interfaces in DTE Mode
When the serial interface is operating in DTE mode, it monitors the DCD signal as the line up/down indicator. By default, the attached DCE device sends the DCD signal. When the DTE interface detects the DCD signal, it changes the state of the interface to up.
SDLC Multidrop Environments
In some configurations, such as an Synchronous Data Link Control (SDLC) multidrop environment, the DCE device sends the DSR signal instead of the DCD signal, which prevents the interface from coming up. Use this command to tell the interface to monitor the DSR signal instead of the DCD signal as the line up/down indicator.
Examples
The following example shows how to configure serial interface 0 to monitor the DSR signal as the line up/down indicator:
Router(config)# interface serial 0
Router(config-if)# ignore-dcd
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