T1 - a specification for a transmission line. The specification details the input and output characteristics and the bandwidth. T1 lines run at 1.544 Mbps and provide for 24 data channels. In common usage, the term "T1" is used interchangeably with "DS1."

T1 Link - A wideband digital carrier facility used for transmission of digitized voice, digital data, and digitized image traffic. This link is composed of two twisted-wire pairs that can carry 24 digital channels, each operating at 64K bps at the aggregate rate of 1.544M bps, full duplex. Also referred to as DS-1.

T3 - a specification for a transmission line, the equivalent of 28 T1 lines. T3 lines run at 44.736 Mbps. In common usage, the term "T3" is used interchangeably with "DS3."

Tachometer - in ForeView, the tachometer shows the level of activity on a given port. The number in the tachometer shows the value of a chosen parameter in percentage, with a colored bar providing a semi-logarithmic representation of that percentage.

Tagging - A Tag or Mark is used to distinguish lower priority cells from higher or guaranteed cells in the same data flow. CLP=0 cells when tagged become CLP=1 cells.

Talk Time -The length of time you can talk on your portable or transportable cellular phone without recharging the battery. The battery capacity of a cellular portable or transportable is usually expressed in terms of so many minutes of talk time OR so many hours of standby time. When you’re talking, the phone draws more power from the battery.

Tap - (1) An electrical connection permitting signals to be transmitted onto or off a bus; (2) the link between the bus and the drop cable that connects the workstation to the bus; and (3) a device used on CATV cables for matching impedance or connecting subscriber drops.

TAT (Theoretical Arrival Time) - Assumes equally spaced cells arriving at an anticipated rate. Cells that arrive too early are considered non-conforming.

TAXI (Transparent Asynchronous Transmitter/Receiver Interface) - Encoding scheme used for FDDI LANs as well as for ATM; supports speed typical of 100 Mbps over multimode fiber.

TBE (Transit Buffer Exposure) - For ABR, defines the number of cells supported prior to a control loop being established.

TC (Transmission Convergence) - generates and receives transmission frames and is responsible for all overhead associated with the transmission frame. The TC sublayer packages cells into the transmission frame.

TCA (TeleCommunications Association) - A major association of West-of-the-Rockies telecommunications management professionals.

TCL (Tool Command Language) - the scripting language ForeView is written in.

TCP (Transmission Control Protocol) - a specification for software that bundles and unbundles sent and received data into packets, manages the transmission of packets on a network, and checks for errors.

TCP/IP (Transmission Control Protocol/Internet Protocol) - a set of communications protocols that has evolved since the late 1970s, when it was first developed by the Department of Defense. Because programs supporting these protocols are available on so many different computer systems, they have become an excellent way to connect different types of computers over networks.

TCR (Tagged Cell Rate) - An ABR service parameter, TCR limits the rate at which a source may send out-of-rate forward RM-cells. TCR is a constant fixed at 10 cells/second.

TCS (Transmission Convergence Sublayer) -This is part of the ATM physical layer that defines how cells will be transmitted by the actual physical layer.

TDM (Time Division Multiplexing) - a method of traditional digital multiplexing in which a signal occupies a fixed, repetitive time slot within a higher-rate signal.

TDMA (Time Division Multiple Access) - A technique used in satellite communications to interweave multiple conversations into one transponder so as to appear to get simultaneous conversations.

TE (Terminal Equipment) - Terminal equipment represents the endpoint of ATM connection(s) and termination of the various protocols within the connection(s).

Technical Reference - A publication that gives additional descriptive and technical details to supplement a tariff.

Telephone Exchange - In the U.S., an area within which telephone service is provided without toll charges. In Europe, a telephone central office.

Telephony - The science of converting voices and other sounds into electrical signals which can be transmitted by wire, fiber or radio and reconverted to audible sound upon receipt.

Telnet - a TCP/IP protocol that defines a client/server mechanism for emulating directly-connected terminal connections.

Terminal Block - An insulating base with binding posts to make connections where sets of terminals are mounted.

Terminal Board - An insulating base on which terminals for wires or cables have been mounted.

Terminal Lug - Threaded stud with nuts which are used to clamp wires into firm contact.

Terminal Strip - Block carrying terminals or tags for the connection of cables or jumper wires.

Test Jack - A jack providing access to a circuit for test purposes.

Test Lead - Insulated wires with test clips used to make temporary connections while tests are being carried out.

Test Set - A telephone handset with extra electronics designed to test telephone circuits (also called a butt set).

TFTP (Trivial File Transfer Protocol) - Part of IP, a simplified version of FTP that allows files to be transferred from one computer to another over a network.

Thermistor - A thermally-sensitive resistor whose resistance changes with temperature.

Three Phase - A combination of three electrical circuits, windings, voltages, etc., having symmetrical phase differences of 120 electrical degrees.

Throughput - The number of bits, characters, or blocks which can pass through a data communications system, or portion thereof, when the system is working at saturation.

Thyristor - A semiconductor used as a gate circuit. The solid state equivalent of a thyratron. Synonymous with Silicon Controlled Rectifier (SCR).

Thyristor Rectifier - Rectifier using a thyristor as rectifier and as voltage controlling device.

TIA (Telecommunications Industry Association) - A Washington lobbying and trade association, the result of the merger of the USTA (United States Telephone Association) and the EIA (Electronic Industries Association).

TIF (Telephone Influence Factor) - A measure of the inductive effect exerted by a power system on nearby telephone circuits, represented by the noise level in the telephone receiver.

Tinned Wire - Copper wire coated with tin to make soldering easier.

Tip - (1) The rounded end of a standard telephone switchboard plug; and (2) one of the two speech wires in a central office, the other being called a ring wire.

Tip & Ring - An old fashioned way of saying "plus" and "minus," or ground and positive in electrical in circuits. Tip and Ring are telephony terms. They derive their names from the operator’s cardboard plug. The tip wire was connected to the tip of the plug, and the ring wire was connected to the slip ring around the jack.

TLV (Type/Length/Variable) - An extension that informs the LAN Emulation Server that this client is also MPOA enabled for the ELAN that it is a member of.

TM (Traffic Management) - The traffic control and congestion control procedures for ATM. ATM layer traffic control refers to the set of actions taken by the network to avoid congestion conditions.

ATM layer congestion control refers to the set of actions taken by the network to minimize the intensity, spread and duration of congestion. The following functions form a framework for managing and controlling traffic and congestion in ATM networks and may be used in appropriate combinations.

Connection Admission Control
Feedback Control
Usage Parameter Control
Priority Control
Traffic Shaping
Network Resource Management
Frame Discard
ABR Flow Control

Token - The Token Bucket model was developed by modifying the Leaky Bucket model. The "token" in this case is a gating process for movement of cells through a policing action.

Token Ring - a network access method in which the stations circulate a token. Stations with data to send must have the token to transmit their data.

Tone Generator - Machine or solid state device which produces the information tones needed in a telephone system, e.g., dial tone, busy tone, or ringing tone.

Tone Monitor - A device which continually monitors the tone supplies at a central office and gives an alarm if the tone supply or the interruption circuit fails.

topology - a program that displays the topology of a Marconi ATM network. An updated topology can be periodically re-displayed by use of the interval command option.

Topology Aggregation - The process of summarizing and compressing topology information at a hierarchical level to be advertised at the level above.

Topology Attribute - A generic term that refers to either a link attribute or a nodal attribute.

Topology Constraint - A topology constraint is a generic term that refers to either a link constraint or a nodal constraint.

Topology Database - The database that describes the topology of the entire PNNI routing domain as seen by a node.

Topology Metric - A generic term that refers to either a link metric or a nodal metric.

Topology State Parameter - A generic term that refers to either a link parameter or a nodal parameter.

Total Failure - Fault condition which has completely interrupted a service.

Traffic - the calls being sent and received over a communications network. Also, the packets that are sent on a data network.

Traffic Parameter - A parameter for specifying a particular traffic aspect of a connection.

Traffic Shaping - The alteration of a traffic stream on a particular connection to increase network efficiency.

Trailer - the protocol control information located at the end of a PDU.

Transducer - A device which converts one form of energy into another. The diaphragm in the telephone and the carbon microphone in the transmitter are transducers. They change variations in sound pressure (your voice) to variations in electricity, and vice versa.

Transformer - An electrical device consisting of a magnetic core and one or more windings, used to change the voltage of an AC circuit from one value to another or to isolate portions of the circuits from others.

Transient - A temporary change in steady state conditions when one parameter, such as load, is changed.

Transistor - A semiconductor device used in amplifiers, oscillators, and control circuits in which current flow is modulated by voltage or current applied to electrodes. Most transistors are based on the use of silicon.

Transit Delay - the time difference between the instant at which the first bit of a PDU crosses one designated boundary, and the instant at which the last bit of the same PDU crosses a second designated boundary.

Transmobile - The transmobile (not to be confused with transportable) is another type of cellular phone. It is essentially a standard 3-watt mobile unit — without an external battery pack — that can be quickly and easily moved from one vehicle to another. It draws its power from the vehicle’s battery via a cigarette lighter plug.

Transport Layer - Layer Four of the OSI reference model that is responsible for maintaining reliable end-to-end communications across the network.

trap - a program interrupt mechanism that automatically updates the state of the network to remote network management hosts. The SNMP agent on the switch supports these SNMP traps.

TRFR - TRansFeR.

Triac - A gated switching device which will conduct in either direction.

Trickle Charge - A continuous charge of a storage batteryusing a small current.

Trm - For ABR, it refers to the maximum time between forward RM-cells from an active source (range of .78 to 100 as the default).

Turnkey System - An entire telephone system with hardware and software assembled and installed by a vendor and sold as a total package.

20-Cycle Ringing - Ringing using a nominal 20 Hz signal to ring bells or operate calling ndicators.

Twisted Pair - Insulated wire in which pairs are twisted together. Commonly used for telephone connections, and LANs because it is inexpensive.