Terminal (telecommunication)

In the context of telecommunications, a terminal is a device which ends a telecommunications link and is the point at which a signal enters and/or leaves a network. Examples of equipment containing network terminations are telephones, fax machines, computer terminals and network devices, printers and workstations.

Network Tree diagram
Network terminal nodes are at the edges of the network

See also

External links

Communication endpoint

A communication endpoint is a type of communication network node. It is an interface exposed by a communicating party or by a communication channel. An example of the latter type of a communication endpoint is a publish-subscribe topic

or a group in group communication systems.A communication endpoint is a discoverable node of communication whose scope may be varied to narrow or broaden the discovery zone. Endpoints facilitate a standard programmable layer of abstraction whereby heterogeneous software systems and/or subsystems may communicate with each other and that the means of communication are decoupled from the communicating subsystems.

Data link

In telecommunication a data link is the means of connecting one location to another for the purpose of transmitting and receiving digital information. It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver (two pieces of data terminal equipment) and the interconnecting data telecommunication circuit. These are governed by a link protocol enabling digital data to be transferred from a data source to a data sink.

There are at least three types of basic data-link configurations that can be conceived of and used:

Simplex communications, most commonly meaning all communications in one direction only.

Half-duplex communications, meaning communications in both directions, but not both ways simultaneously.

Duplex communications, communications in both directions simultaneously.In civil aviation, a data-link system (known as Controller Pilot Data Link Communications) is used to send information between aircraft and air traffic controllers when an aircraft is too far from the ATC to make voice radio communication and radar observations possible. Such systems are used for aircraft crossing the Atlantic and Pacific oceans. One such system, used by Nav Canada and NATS over the North Atlantic, uses a five-digit data link sequence number confirmed between air traffic control and the pilots of the aircraft before the aircraft proceeds to cross the ocean. This system uses the aircraft's flight management computer to send location, speed and altitude information about the aircraft to the ATC. ATC can then send messages to the aircraft regarding any necessary change of course.

In unmanned aircraft, land vehicles, boats, and spacecraft, a two-way (full-duplex or half-duplex) data-link is used to send control signals, and to receive telemetry.

Data terminal equipment

Data terminal equipment (DTE) is an end instrument that converts user information into signals or reconverts received signals. These can also be called tail circuits. A DTE device communicates with the data circuit-terminating equipment (DCE). The DTE/DCE classification was introduced by IBM.

V.35 is a high-speed serial interface designed to support both higher data rates and connectivity between DTEs (data-terminal equipment) or DCEs (data-communication equipment) over digital lines.

Two different types of devices are assumed on each end of the interconnecting cable for a case of simply adding DTE to the topology (e.g. to a hub, DCE), which also brings a less trivial case of interconnection of devices of the same type: DTE-DTE or DCE-DCE. Such cases need crossover cables, such as for the Ethernet or null modem for RS-232.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.

Usually, the DTE device is the terminal (or a computer emulating a terminal), and the DCE is a modem or another carrier-owned device.

A general rule is that DCE devices provide the clock signal (internal clocking) and the DTE device synchronizes on the provided clock (external clocking). D-sub connectors follow another rule for pin assignment.

25 pin DTE devices transmit on pin 2 and receive on pin 3.

25 pin DCE devices transmit on pin 3 and receive on pin 2.

9 pin DTE devices transmit on pin 3 and receive on pin 2.

9 pin DCE devices transmit on pin 2 and receive on pin 3.This term is also generally used in the Telco and Cisco equipment context to designate a network device, such as terminals, personal computers but also routers and bridges, that's unable or configured not to generate clock signals.

Hence a direct PC to PC Ethernet connection can also be called a DTE to DTE communication. This communication is done via an Ethernet crossover cable as opposed to a PC to DCE (hub, switch, or bridge) communication which is done via an Ethernet straight cable.

End instrument

In telecommunications an end instrument is a piece of equipment connected to the wires at the end of a telecommunications link. In telephony, this is usually a telephone connected by a local loop. End instruments that relate to data terminal equipment include printers, computers, barcode readers, automated teller machines (ATMs) and the console ports of routers.

End system

In networking jargon, the computers that are connected to a computer network are sometimes referred to as end systems or end stations. They are labeled end systems because they sit at the edge of the network. The end user always interacts with the end systems. End systems are the devices that provide information or services.End systems that are connected to the Internet are also referred to as Internet hosts; this is because they host (run) Internet applications such as a web browser or an email retrieval program. The Internet’s end systems include some computers with which the end user does not interact. These include mail servers and web servers. With the emergence of the Internet of things, household items (such as toasters and refrigerators) as well as portable, handheld computers and digital cameras are all being connected to the Internet as end systems.

End systems are usually connected to each other using switching devices known as routers rather than using single communication link. The path that transmitted information takes from the sending end system, through a series of communications links and routers, to the receiving end system is known as a route or path through the network.

Node (networking)

In telecommunications networks, a node (Latin nodus, ‘knot’) is either a redistribution point or a communication endpoint. The definition of a node depends on the network and protocol layer referred to. A physical network node is an active electronic device that is attached to a network, and is capable of creating, receiving, or transmitting information over a communications channel. A passive distribution point such as a distribution frame or patch panel is consequently not a node.

Network topology
and switching

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