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

Check thedocumentation that ships with your serial device to determine if it is aDTE or DCE device. If you cannot find the information in the serialdevice documentation. This table summarizes serial devices that can beconnected to the router serial port and whether the device is considereda DTE or DCE device. The Cisco 805 router is a DTE device by default.