Cisco Systems C819HG4GVK9 Setting Transmit Delay, Configuring DTR Signal Pulsing, 8-11, Purpose

Chapter 8 Configuring the Serial Interface

How to Configure Serial Interfaces

DETAILED STEPS

	Command or Action	Purpose
Step 1	invert txclock	Inverts the clock signal on an interface.
	Example:
	Router(config-if)# invert txclock
Step 2	invert rxclock	Inverts the phase of the RX clock on the UIO serial
		interface, which does not use the T1/E1 interface.
	Example:
	Router(config-if)# invert rxclock

Setting Transmit Delay

It is possible to send back-to-back data packets over serial interfaces faster than some hosts can receive them. You can specify a minimum dead time after transmitting a packet to remove this condition. This setting is available for serial interfaces on the MCI and SCI interface cards and for the HSSI or MIP. Use one of the following commands, as appropriate for your system, in interface configuration mode.

Command	Purpose
Router(config-if)# transmitter-delay	Sets the transmit delay on the MCI and SCI synchronous serial interfaces.
microseconds
Router(config-if)# transmitter-delay	Sets the transmit delay on the HSSI or MIP.
hdlc-flags

Configuring DTR Signal Pulsing

You can configure pulsing Data Terminal Ready (DTR) signals on all serial interfaces. When the serial line protocol goes down (for example, because of loss of synchronization), the interface hardware is reset and the DTR signal is held inactive for at least the specified interval. This function is useful for handling encrypting or other similar devices that use the toggling of the DTR signal to reset synchronization. To configure DTR signal pulsing, use the following command in interface configuration mode.

Command	Purpose
Router(config-if)# pulse-timeseconds	Configures DTR signal pulsing.

Ignoring DCD and Monitoring DSR as Line Up/Down Indicator

By default, when the serial interface is operating in DTE mode, it monitors the Data Carrier Detect (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.

In some configurations, such as an SDLC multidrop environment, the DCE device sends the Data Set Ready (DSR) signal instead of the DCD signal, which prevents the interface from coming up. To tell the interface to monitor the DSR signal instead of the DCD signal as the line up/down indicator, use the following command in interface configuration mode.

	Cisco 819 Series Integrated Services Routers Software Configuration Guide
OL-23590-02		8-11