Multi Tech Equipment MTA128ST - Manual (Page 53)

Glossary
MTA128ST/NT 53
G l o s s a r y
Symbol
2B1Q (2 bits, 1 quarternary)—A line code at layer
one for the BRI U interface. Two bits of data (2B) are
mapped into one of four line values (1Q, or
1quarternary). This coding scheme
allows a single copper pair to carry 160 Kbps of
information bidirectionally and simultaneously at a
distance of up to three miles.
A
ACK
(acknowledgement code)—A communications
code sent from a receiving modem to a transmitting
modem to indicate that it is ready to accept data. It is
also used to acknowledge the error-free receipt of
transmitted data. Contrast with NAK.
address— A numbered location inside a computer.
The computer uses addresses to access resources
such as video cards, serial ports, memory, etc.
analog signal— A waveform that has amplitude,
frequency, and phase, which takes on a range of
values between its maximum and minimum points.
analog transmission— A type of telecommunications
that uses an analog signal as a carrier of voice, data,
video, etc. An analog signal becomes a carrier when it
is modulated by altering its phase, amplitude, and/or
frequency to correspond with the source signal. Com-
pare with digital transmission.
API (application program interface)— A software
module created to allow dissimilar, or incompatible
applications programs to transfer information over a
communications link. APIs may be simple or complex;
they are commonly required to link computer
applications with mainframe programs.
ASCII (American Standard Code for Information
Interchange)— Pronounced ass-key. A binary code for
data that is used in communications and in many
computers and terminals. The code is used to
represent numbers, letters, punctuation, and control
characters. The basic ASCII code is a 7-bit character
set, which defines 128 possible characters. The
extended 8-bit ASCII code defines 255 characters.
ASI (application services interface)—A software
module that creates the interface between a LAN-
connected PC and the network operating system. ASIs
packetize computer data for transport over the
network. NASI, NCSI, MCSI and NETCI are specific
examples.
AT commands— A standard set of commands used
to control modems. Each AT command string begins
with the characters AT, which get the attention of the
modem before the actual command is issued. See
also command mode.
B
background—
An activity that takes place in the
computer while you are running another application.
In other words, the active user interface does not
correspond to the background task.
bandwidth— The transmission capacity of a computer
channel, communications line or bus. It is expressed in
cycles per second (hertz), the bandwidth being the difference
between the lowest and highest frequencies transmitted. The
range of usable frequencies that a transmission medium will
pass without unacceptable attenuation or distortion.
Bandwidth is a factor in determining the amount of
information and the speed at which a medium can transmit
data or other information.
Bandwidth-on-Demand—
Ability to request the amount of
data
speed you need in any situation. Allows you to
automatically add and drop b-channels according to your
preference; you pay only for the bandwith you need.
basic access—
A term that describes a simple standardized
combination of access channels that constitute the access
arrangements for most ISDN users.
B-channel (bearer channel)—A 64 Kbps ISDN channel
used for digital high-speed data or voice transmission.
Simultaneous voice and data transmission requires
subscription to two B-channels. A voice call can be placed
or received while a data call is in process (or vice versa);
however, two simultaneous voice or two simultaneous
data calls are not supported.
bearer capability (BC)—The level of functionality provided by
the ISDN B-channel (e.g., data, 3.1 KHz audio, etc.).
bearer services—
A set of ISDN functions provided by the
B-channel, such as digital telephony, toll-free
inbound/outbound calls, 64 Kbps circuit switched data, X.25
packet switched data, and frame relay data.
bit —A bit (binary digit) is a basic unit of information used in
computing and other digital electronics. It can take a value
of either 1 or 0, represented in a computer by a high or low
electrical charge.
BONDING (Bandwidth on Demand Interoperability Group)—
An inverse multiplexing method that combines multiple ISDN
channels into a single channel for enhanced throughput.
Trademark of the BONDING Consortium.
BONDING mode 1— An industry-standard ISDN B channel
aggregation protocol that was developed by the Bandwidth On
Demand Interoperability Group. This mode supports user data
rates that are multiples of the bearer rate. It provides the full
available bandwidth, but no in-band monitoring. Mode 1 is
common to all implementations of BONDING; Modes 0, 2,
and 3 are optional.
BONDING Consortium— A group that develops specifications
for common control and synchronization for management of
high-speed data over the public network.
BONDING Specification 1.0— The Version 1.0 BONDING
specification (August 1992) defines four modes of inverse
multiplexing interoperability. It allows devices from various
manufacturers to subdivide a wideband signal into 64
Kbps or 56 Kbps channels, and then pass the individual
channels over a switched digital network, recombining them
into a single high-speed signal at the receiving device.
BONDING Specification 1.1— The Version 1.1 BONDING
specification (September 1993) incorporates changes to the
1.0 specification resulting from interworking tests among
various vendors, and comments from the TIA standardization
process. No changes were made to the BONDING
algorithm or procedures.
bps (bits per second)—The unit of speed at which data bits
can be transmitted or received. Bps differs from baud when