DTE and DCE are defined as Data Terminal Equipment and Data
Communication Equipment

Uses of DCE and DTE

DCE is connected to Console port on CPU for Router Configuration.

DTE is used for connecting between Systems on Network.

How to identify DCE

Use following command to check which interface is DTE or DCE

Show controllers serial 0/1/0

Interface Serial0/1/0

Hardware is PowerQUICC MPC860

DTE V.35 clocks stopped.

Show controllers serial 0/1/0

Interface Serial0/1/0

Hardware is PowerQUICC MPC860

DCE V.35, no clock

About the DCE and DTE

When you're dealing with 9-pin serial, the RS-232 standards say that DCE devices should have a female DB-9 connector, and DTE devices should have a male DB-9 connector.

That makes them easy to tell apart.

But if you want to tell, find out which pins in your connector correspond to the Data Set Ready (DSR) and Data Terminal Ready (DTR) signal lines.

It is the DCE that raises Data Set Ready and the DTE that replies with Data Terminal Ready.

So check the voltage on those pins at the device connector, without an RS-232 cable plugged in, and you can tell whether it is a DCE or a DTE