Specifications

Configuring the Router 4-15
Configuring the Router
Setting Synchronous Serial Ports
Take the following steps to configure a low-speed asynchronous serial port to be a
low-speed synchronous serial port:
Step 1 Connect a terminal by following the instructions in the section “Connecting the
Console Terminal and Modem” in the chapter “Installing the Router” and then
power up the router.
Step 2 Enter the config terminal command at the enable prompt to enter configuration
mode:
Router# config terminal
You can now make changes to the configuration. Press Ctrl-Z to exit configuration
mode.
Step 3 Enter the interface command to select the port you are configuring:
interface serial 2
Step 4 Enter the physical-layer command to set the port to synchronous:
physical-layer sync
Setting Half-Duplex Mode
Low-speed serial ports that are set as DCE can be set to use either controlled carrier mode
or constant carrier mode.
Controlled carrier mode sets the interface to deactivate DCD until a transmission is sent to
the interface. DCD is then activated, and the interface waits an amount of time you
configure, and then transmits the data. After the transmission, the interface waits for a
period of time and then deactivates DCD.
Constant carrier mode (the default for low-speed interfaces) activates DCD at all times.
Take the following steps to enable controlled carrier mode:
Step 1 Connect a terminal by following the instructions in the section “Connecting the
Console Terminal and Modem” in the chapter “Installing the Router” and then
power up the router.