Serial Interfaces Overview

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.

There are no serial interface-specific logical properties. For information about general logical properties that you can configure, see Configuring Logical Interface Properties. On J Series routers, link fragmentation and interleaving (LFI) and Multilink Point-to-Point Protocol (MLPPP) support has been extended to serial interfaces. This support on serial interfaces is the same as the existing LFI and MLPPP support on T1 and E1 interfaces.

Related Topics

• Example: Physical Interface Configuration Statements for Serial Interfaces
• 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