Cisco Systems C819GUK9 manual Specifying the Serial Network Interface Module Timing, Ignore-dcd

Chapter 8 Configuring the Serial Interface

How to Configure Serial Interfaces

SUMMARY STEPS

1. ignore-dcd

DETAILED STEPS

	Command or Action	Purpose
Step 1	ignore-dcd	Configures the serial interface to monitor the DSR
		signal as the line up/down indicator.
	Example:
	Router(config-if)# ignore-dcd

Caution Unless you know for certain that you really need this feature, be very careful using this command. It will hide the real status of the interface. The interface could actually be down and you will not know just by looking at show displays.

Specifying the Serial Network Interface Module Timing

On Cisco 819 ISRs, you can specify the serial Network Interface Module timing signal configuration. When the board is operating as a DCE and the DTE provides terminal timing (SCTE or TT), you can configure the DCE to use SCTE from the DTE. When running the line at high speeds and long distances, this strategy prevents phase shifting of the data with respect to the clock.

To configure the DCE to use SCTE from the DTE, use the following command in interface configuration mode.

SUMMARY STEPS

1. dce-terminal-timing enable

DETAILED STEPS

Command or Action	Purpose
Step 1 dce-terminal-timing enable	Configures the DCE to use SCTE from the DTE.

Example:

Router(config-if)# dce-terminal-timing enable

When the board is operating as a DTE, you can invert the TXC clock signal it gets from the DCE that the DTE uses to transmit data. Invert the clock signal if the DCE cannot receive SCTE from the DTE, the data is running at high speeds, and the transmission line is long. Again, this prevents phase shifting of the data with respect to the clock.

To configure the interface so that the router inverts the TXC clock signal, use the following command in interface configuration mode.

	Cisco 819 Series Integrated Services Routers Software Configuration Guide
8-12	OL-23590-02