Configuring Serial Interfaces

Devices that communicate over a serial interface are divided into two classes: data terminal equipment (DTE) and data circuit-terminating equipment (DCE). Juniper Networks Serial Physical Interface Cards (PICs) have two ports per PIC and support full-duplex data transmission. These PICs support DTE mode only. On the Serial PIC, you can configure three types of serial interfaces:

• EIA-530—An Electronics Industries Alliance (EIA) standard for the interconnection of DTE and DCE using serial binary data interchange with control information exchanged on separate control circuits.
• V.35—An ITU-T standard describing a synchronous, physical layer protocol used for communications between a network access device and a packet network. V.35 is most commonly used in the United States and in Europe.
• X.21—An ITU-T standard for serial communications over synchronous digital lines. The X.21 protocol is used primarily in Europe and Japan.

The following standards apply to serial interfaces:

• TIA/EIA Standard 530, High-Speed 25-Position Interface for Data Terminal Equipment and Data Circuit-Terminating Equipment, defines the signals on the cable and specifies the connector at the end of the cable.
• TIA/EIA Standard 232, Interface between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, describes the physical interface and protocol for serial data communication.
• ITU-T Recommendation V.35, Data Transmission at 48 kbit/s Using 60-108 kHz Group Band Circuits. Note that the Juniper Networks Serial PIC supports V.35 interfaces with speeds higher than 48 kilobits per second.
• ITU-T Recommendation X.21, Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment for Synchronous Operation on Public Data Networks.

To configure serial physical interface properties, include the serial-options statement at the [edit interfaces se-fpc/pic/port] hierarchy level:

[edit interfaces se-fpc/pic/port]

serial-options { 

    clock-rate rate;

    clocking-mode (dce | dte | loop);

    control-leads {

        control-signal (assert | de-assert | normal);

        cts (ignore | normal | require);

        dcd (ignore | normal | require);

        dsr (ignore | normal | require);

        dtr signal-handling-option;

        ignore-all;

        indication (ignore | normal | require);

        rts (assert | de-assert | normal);

        tm (ignore | normal | require);

    }

    control-polarity (negative | positive);

    cts-polarity (negative | positive);

    dcd-polarity (negative | positive);

    dsr-polarity (negative | positive);

    dtr-circuit (negative | positive);

    dtr-polarity (negative | positive);

    encoding (nrz | nrzi);

    idle-cycle-flag flag;

    indication-polarity (negative | positive);

    line-protocol protocol;

    loopback mode;

    rts-polarity (negative | positive);

    tm-polarity (negative | positive);

    transmit-clock invert;

}

This chapter discusses configuration of the following serial interface properties:

• Configuring the Serial Line Protocol
• Configuring the Serial Clocking Mode
• Configuring the Serial Idle Cycle Flag
• Configuring the Serial Signal Handling
• Configuring the Serial DTR Circuit
• Configuring Serial Signal Polarities
• Configuring Serial Loopback Capability
• Configuring Serial Line Encoding

There are no serial interface-specific logical properties. For information about general logical properties that you can configure, see Configuring Logical Interface Properties.