Motorola P880 manual Typical Connection Between the Switch and a Modem

Connecting a

Modem

Configuring the

Serial Console Port

as a PPP Console

In order to use the serial console port as a PPP console, you must connect a modem to the switch. When you use the specified serial cable and connectors, the switch will convert the normal DCE interface to a DTE interface that is used by modems.

When the switch is configured for PPP mode, it will periodically send the modem config string from the serial console port. This will synchronize the baud rates between the modem and the console port and configure the modem to operate with the switch’s DTE interface.

The switch does not use any output signals except for TXD. It uses the DTR (converted to DSR by the specified cable and connectors) input connected to the modem DCD output, to detect that the modem is connected. It supports XON/XOFF flow control (or none).

To connect a modem:

1.Attach a DB25M-RJ45 (P/N 38210003)connector to the modem.

2.Attach the DB9M-RJ45 MDCE connector to the switch’s serial console port on the front panel of the switch.

Figure 17. Typical Connection Between the Switch and a Modem

Typical Connection between Cajun

Switch and Modem

DB25 M - RJ45	Pin 2 - TXD		Pin 2 - TXD
P/N 38210003	Pin 3	- RXD	Pin 3 - RXD	DB9M - RJ45
	Pin 7	- GND	Pin 4 - DTR in		MDCE
	Pin 8 - DCD out		Pin5 - GND
	pin 20 - DTR in		pin 6 - NC

Modem

Cajun Switch

You can reconfigure the console serial port as a PPP Console to support a dial-in PPP connection using a modem.

*Note: The lack of an IP address for the PPP serial interface causes the switch to immediately return to sending the modem configuration string. Typing TTY will re-access the CLI login prompt.

Cajun P880 Routing Switch Installation Guide 2 - 31