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ignore-dcd

what is exact use of "ignore-dcd"?

is it good to use or not this command on serial interface?

dporter

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Hall of Fame Super Bronze

Re: ignore-dcd

Extracted from CCO

++++++

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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