Cisco Systems 805 manual How to Select a Serial Cable, Selectable DTE or DCE

How to Select a Serial Cable

DTE or DCE

There are two types of devices that can communicate over a serial interface: DCE and DTE. A DCE provides a physical connection to a network and forwards traffic. A DTE connects to a network through a DCE device. Typically, a DTE device is connected to a DCE device (or vice versa) rather than another DTE device.

Check the documentation that ships with your serial device to determine if it is a DTE or DCE device. If you cannot find the information in the serial device documentation, refer to Table A-1. This table summarizes serial devices that can be connected to the router serial port and whether the device is considered a DTE or DCE device. The Cisco 805 router is a DTE device by default. Table A-2 describes the type of cable needed to connect a DTE or DCE device to your router.

Table A-1	DTE and DCE Devices
Serial Device		DTE	DCE	Selectable DTE or DCE1
Modems (asynchronous and synchronous)			X
Channel service unit/data service unit			X
(CSU/DSU)
Multiplexers			X
Terminals		X
Routers				X
Hubs				X
Switches				X
Access server				X

1 These serial devices usually have a jumper, switch, or software command that selects the DTE or DCE mode.

Table A-2 Cable Type Needed to Connect Serial Devices

Serial Device Type Cable Type Needed

DTEDCE

A-2Cisco 805 Router Hardware Installation Guide