1000Base-T

One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 1000 Mbps (baseband) carried over twisted pair. Also known as Gigabit Ethernet or GigE.

100Base-T

One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 100 Mbps (baseband) carried over twisted pair. Also known as Fast Ethernet.

10Base-T

One of the more common types of Ethernet Local Area Networking (LAN) cabling. Specifies 10 Mbps (baseband) carried over twisted pair.

ARCnet

A network developed by DataPoint. Originally proprietary, by the late 1980s it was no longer proprietary and had about as large a market share as Ethernet among small businesses. It was almost as fast and was considerably cheaper at the time.

BNC

A connector for coaxial cable such as that used for some video connections and RG58 "cheapernet" connections. A BNC connector has a bayonet-type shell with two small knobs on the female connector which lock into spiral slots in the male connector when it is twisted on. Different sources expand BNC as Bayonet Navy Connector, British Naval Connector, Bayonet Neill Concelman, or Bayonet Nut Connection.

Communications port

A connector for a communications interface, usually, a serial port.

Daisy chain

A bus wiring scheme in which, for example, device A is wired to device B, device B is wired to device C, etc. The last device is normally wired to a resistor or terminator. All devices may receive identical signals or, in contrast to a simple bus, each device in the chain may modify one or more signals before passing them on.

DIN

The German standardization connector type body, also a member of ISO.

Ethernet

A local-area network (LAN) architecture developed by Xerox Corporation in cooperation with DEC and Intel in 1976. Ethernet uses a bus or star topology and supports data transfer rates of 10 Mbps. The Ethernet specification served as the basis for the IEEE 802.3 standard, which specifies the physical and lower software layers. Ethernet uses the CSMA/CD access method to handle simultaneous demands. It is one of the most widely implemented LAN standards. A newer version of Ethernet, called 100Base-T (or Fast Ethernet), supports data transfer rates of 100 Mbps. And the newest version, Gigabit Ethernet supports data rates of 1 gigabit (1,000 megabits) per second.

Ethernet IP

Ethernet/IP (Ethernet Industrial Protocol) is a network communication standard capable of handling large amounts of data at speeds of 10 Mbps or 100 Mbps, and at up to 1500 bytes per packet. The specification uses an open protocol at the Application layer. It is especially popular for control applications.

Ethernet Protocols

802.3 is a standard specification for Ethernet, a method of physical communication in a local area network (LAN), which is maintained by the Institute of Electrical and Electronics Engineers (IEEE).

Fiber Node

A point of interface between a fiber trunk and the coaxial distribution.

Fiber Optics

(1) Very thin and pliable tubes of glass or plastic used to carry wide bands of frequencies. (2) Transmission medium that uses glass or plastic fibers vs. other, copper-based wires to transmit data or voice signals. Fiber-optic cable offers much greater capacity and transmission speeds than traditional mediums.

Gateway

A node on a network that serves as an entrance to another network. In enterprises, the gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In homes, the gateway is the ISP that connects the user to the internet. In enterprises, the gateway node often acts as a proxy server and a firewall. The gateway is also associated with both a router, which use headers and forwarding tables to determine where packets are sent, and a switch, which provides the actual path for the packet in and out of the gateway.

Hub

A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.

IEEE-1394

An electronics standard for connecting devices to a personal computer or set-top box. IEEE-1394 provides a single plug-and-socket connection on which up to 63 devices can be attached with data transfer speeds up to 400 Mbps (megabits per second). The standard describes a serial bus or pathway between one or more peripheral devices and a host's microprocessor. Also known as Firewire or i.Link.

Impedance

Resistance to alternating-current flow.

I/O

Short for input/output. The term I/O is used to describe any program, operation or device that transfers data to or from a computer and to or from a peripheral device. Every transfer is an output from one device and an input into another. Devices such as keyboards and mouses are input-only devices while devices such as printers are output-only. A writable CD-ROM is both an input and an output device.

Jumper

A removable wire or small plug whose presence or absence is used to determine some aspect of hardware configuration.

Kilo (K)

Meaning one thousand. Communications and computer terminology, however, uses the term K or Kilo differently. In communications terminology, one K is equal to 1000, but when measuring computer memory or disk space, one K is equal to 1024.

KiloBits Per Second (Kbps)

One Kbps is equal to 1000 bits transmitted in one second.

Local Area Network (LAN)

A LAN is a collection of computing equipment at a single location (e.g., an office building or campus) that communicate with each other to share resources and information, such as disk storage and files, printers, and e-mail. See also WAN. Or a non-public data network in which serial transmission is used for direct data communication among data stations located on the user's premises.

Low Smoke Zero Halogen (LSZH)

Low Smoke Zero Halogen cable reduces the amount of toxic and corrosive gas emitted during combustion. LSZH cable produces less smoke and releases little or no halogen gas when burned.

MegaHertz (MHz)

One million cycles per second.

Network

Hardware and software data communication systems. The ISO seven layer model attempts to provide a way of partitioning any computer network into independent modules from the lowest (physical) layer to the highest (application) layer. Many different specifications exist at each of these layers. Networks are often also classified according to their geographical extent: local area network (LAN), metropolitan area network (MAN), wide area network (WAN) and also according to the protocols used.

Null modem

A cable, especially an RS-232 cable, for connecting serial ports on two computers directly, rather than via modems. Since, according to the specification, both computers should transmit on pin three of their RS-232 connectors and receive on pin two, a null modem cable needs to connect one computer's pin two to the other's pin three and vice versa. It also needs to have male connectors at both ends (again, according to the specification).

Ohm

The standard unit of resistance, reactance and impedance. A resistant of 1 ohm will conduct 1 ampere of current when a voltage of 1 volt is placed across it.

Optical Fiber

An extremely thin, flexible thread of pure glass, able to carry one thousand times the information possible with traditional copper wire.

Pin-out

(Or "pinout") The allocation of logical functions or signals to the electrical connection points (pins) of an integrated circuit or other component or connector.

Plenum cable

Cable that that can be (legally) installed in the plenum (the space between a ceiling and the floor above it). Such cable is (usually) Teflon-coated so that it will not give off toxic fumes when burned. In some parts of the world such cable is required by law.

Protocol

A standard way of communicating across a network. A protocol is the "language" of the network. A method by which two dissimilar systems can communicate. TCP is a protocol which runs over a network.

Proxy Server

A server that sits between a client application, such as a Web browser, and a real server. It intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request to the real server.

Reduction Of Hazardous Substances (RoHS)

European Union regulations enforceable on July 1, 2006 that set maximum concentration limits on hazardous materials used in electrical and electronic equipment. The substances are lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE).

RS-232

In telecommunications, RS-232 (Recommended Standard 232) is a standard for serial binary data signals connecting between a DTE (Data terminal equipment) and a DCE (Data Circuit-terminating Equipment). It is commonly used in computer serial ports. A similar ITU-T standard is V.24.

RS-530

RS-530 is a high speed 25-position interface for Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE).

Serial port

(Or "com port") A connector on a computer to which you can attach a serial line connected to peripherals which communicate using a serial (bit-stream) protocol. The most common type of serial port is a 25-pin D-type connector carrying RS-232 signals. Smaller connectors (e.g. 9-pin D-type) carrying a subset of RS-232 are often used on personal computers. The serial port is usually connected to an integrated circuit called a UART which handles the conversion between serial and parallel data.

T-1 Line

A leased-line connection capable of carrying data at 1,544,000 bits per second, or 1.544 Mbps. Generally, a T-1 line will move a megabyte of data in under 10 seconds. That is still not fast enough for full-screen, full-motion video, for which you need at least 10,000,000 bits per second. T-1 is the fastest speed commonly used to connect networks to the Internet.

T-3 Line

A leased-line connection capable of carrying data at 45,000,000 bits per second, or 45 Mbps. This is more than enough to do full-screen, full-motion video.

TCP/IP

Stands for "Transmission Control Protocol / Internet Protocol" - TCP/IP is a suite of communications protocols that forms the basis for and defines the Internet.

Token ring

A computer local area network arbitration scheme in which conflicts in the transmission of messages are avoided by the granting of "tokens" which give permission to send. A station keeps the token while transmitting a message, if it has a message to transmit, and then passes it on to the next station. Often, "Token Ring" is used to refer to the IEEE 802.5 token ring standard, which is the most common type of token ring.

Twisted pair

A type of cable in which pairs of conductors are twisted together to randomize possible cross-talk from nearby wiring. Inadequate twisting is detectable using modern cable testing instruments.

Universal Serial Bus (USB)

A plug-n-play standard for connecting multiple (up to 127) input/output devices to a single high-bandwidth port. The design of the bus allows hot-swapping of the devices (disconnection and reconnection without powering the computer off) and automatic configuration. The USB peripheral bus standard was developed by Compaq, IBM, DEC, Intel, Microsoft, NEC, and Northern Telecom. The original version of USB (USB1.1) supports a data rate of 12Mbps, while the second version (USB2.0) supports a data rate of 480 Mbps.

Wide Area Network (WAN)

A computer network which usually spans larger geographic area, such as cities, counties, states, nations and planets. WAN's usually employ telephone-type topologies, like T1, T2, T5, ATM, etc. The Internet is a WAN which is held together by LANs, which network computers.