DTE and DCE

The terms “DTE” and “DCE” come from the very beginning of IT networks but they are still present today. Read on to find out what the terms stand for.

“DTE” is the acronym for “Data Terminal Equipment”, i.e. devices like laptops, PCs, printers, IP cameras, etc. “DCE” is the acronym for “Data Communication Equipment” like switches. The golden rule is “Always connect DTE to DCE” as the two have different pin assignments for transmit (Tx) and receive (Rx). This makes sure communication works when DTE (e.g. a PC) is connected to DCE (e.g. a switch). In case one would like to connect two terminal devices, e.g. an IP camera to a laptop one has to use a cross-over patch cord. Connecting two switches is a bit easier: Many switches have an integrated MDI/MDI-X function which automatically detects whether a port is connected to a terminal device or to an other switch and automatically assign transmit and receive accordingly. “MDI” is the acronym for “Medium Dependent Interface”, which is the RJ45 jack. “MDI-X” is the acronym for “Medium Dependent Interface Cross-over”, which is the RJ45 jack with swapped Tx and Rx.