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."
- 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.
- 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."
- 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
- 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
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
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
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
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
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.
- 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
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.
- 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
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.
- 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
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
Usage Parameter Control
Network Resource Management
ABR Flow Control
- 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
- 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
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
- 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
- The process of summarizing and compressing topology information at a
hierarchical level to be advertised at the level above.
- A generic term that refers to either a link attribute or a nodal attribute.
- A topology constraint is a generic term that refers to either a link
constraint or a nodal constraint.
- The database that describes the topology of the entire PNNI routing domain as
seen by a node.
- 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
- 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.
- The alteration of a traffic stream on a particular connection to increase
- 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.
- 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.
- Layer Four of the OSI reference model that is responsible for maintaining
reliable end-to-end communications across the network.
- 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.
- A continuous charge of a storage batteryusing a small current.
- 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.