Find DCE DTE

What are the differences between the DTE (Data Terminal Equipment) and the DCE (Data Communication Equipment) in CCNA? How are the DCE and DTE connected to each other? Who introduced the DTE/DCE classification?

I want to know the difference between the Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment DCE so can you tell me?

[pooja]

Data Terminal Equipment (DTE) is an end instrument that converts user information into signals or reconverts received signals while Data Circuit-Terminating Equipment (DCE) is a device that sits between the data terminal equipment (DTE) and a data transmission circuit.

A DTE device communicates with the data circuit-terminating equipment (DCE). The DTE/DCE classification was introduced by IBM.

Usually, the DTE device is the terminal (or computer), and the DCE is a modem.

A DTE is the functional unit of a data station that serves as a data source or a data sink and provides for the data communication control function to be performed in accordance with the link protocol.

The data terminal equipment may be a single piece of equipment or an interconnected subsystem of multiple pieces of equipment that perform all the required functions necessary to permit users to communicate. A user interacts with the DTE (e.g. through a human-machine interface), or the DTE may be the user.

DTE devices usually transmit on pin connector number 2 and receive on pin connector number 3.

DCE devices are just the opposite: pin connector number 2 receives and pin connector number 3 transmits the signals.

When two devices, that are both DTE or both DCE, must be connected together without a modem or a similar media translator between them, a crossover cable must be used, e.g. a null modem for RS-232 or an Ethernet crossover cable.