AAL (ATM Adaptation Layer) - the AAL divides the user information into
segments suitable for packaging into a series of ATM cells. AAL1 is typically
used for CBR traffic such as voice and real time video, while AAL5 is typically
used for VBR and VBR traffic such as bursty LAN data.
- an association established by the AAL between two or more next higher layer
AAL-1 (ATM Adaptation Layer Type 1)
- AAL functions in support of constant bit rate, time-dependent traffic such as
voice and video.
AAL-2 (ATM Adaptation Layer Type 2)
- This AAL is still undefined by the International Standards bodies. It is a
placeholder for variable bit rate video transmission.
AAL-3/4 (ATM Adaptation Layer Type ¾)
- AAL functions in support of variable bit rate, delay-tolerant data traffic
requiring some sequencing and/or error detection support. Originally two AAL
types, i.e. connection-oriented and connectionless, which have been combined.
AAL-5 (ATM Adaptation Layer Type 5)
- AAL functions in support of variable bit rate, delay-tolerant
connection-oriented data traffic requiring minimal sequencing or error
ABR (Available Bit Rate)
- a type of traffic for which the ATM network attempts to meet that traffic's
bandwidth requirements. It does not guarantee a specific amount of bandwidth
and the end station must retransmit any information that did not reach the far
- A feature found on all new cellular telephones permitting the user to select
either the A (non-wireline) carrier or the B (wireline)
carrier when roaming away from home.
AC (Alternating current)
- Typically refers to the 120 volt electricity delivered by your local power
utility to the outlet in your wall. The current alternates between plus and
minus, 60 times a second.
- See Non-Wireline Cellular Company.
- The final test of a new telephone system.
- Trials carried out to determine if the specified performance and
haracteristics have been met.
- A special fee that local telephone companies are allowed to charge all
telephone customers for the right to connect with the local phone network. The
fee is paid by cellular subscribers, as is a federal 3% telephone excise tax.
- The level of programs and data to which a given terminal and/or operator are
ACD (Automatic Call Distribution/Distributor
- A specialized phone system for handling many incoming calls. Typically used
by airlines, rent-a-car companies, hotels, etc., an ACD has four functions.
First, it will recognize and answer an incoming call. Second, it will look in
its database for instructions on what to do with that call. Third, based on
that databases instructions, it will send the call to a recording that
somebody will be with you soon, please dont hang up. Fourth,
it will send the call to one operator of a group of operators as soon as that
operator has completed their previous call and/or the caller has heard the
- A common way of signaling a telephone. An alternating current (AC) rings the
phone bell and a direct current (DC) is used to work a relay to shut the
ringing off when the called person answers.
AC Distribution Cabinet
- A cabinet housing fuses and/or circuit breakers that distribute commercial or
reserve AC power to equipment in a telephone building. May be floor or wall
ACM (Address Complete Message)
- A BISUP call control message from the receiving exchange to sending exchange
indicating the completion of address information.
ACO (Alarm Cut-Off)
- A switch used to silence an audible alarm while maintaining the visual
ACR (Allowable Cell Rate)
- parameter defined by the ATM Forum for ATM traffic management. ACR varies
between the MCR and the PCR, and is dynamically controlled using congestion
AC Standby Power (Reserve Power)
- Power delivered by an engine alternator set (generator) or UPS during
interruption of commercial power.
Active Communication Satellite
- A satellite with a self-contained energy source, designed to transmit radio
communication signals back to earth.
- A fitting that supplies a passage between two sets of equipment when they
cannot be directly interconnected.
- Physical interface card that supports a particular device and its use of a
particular technology. For example, an ATM network adapter enables a computer
to connect to an ATM network.
Adaptive Differential Pulse Code Modulation (ADPCM) -
A technique that allows analog voice signals to be carried on a 32K bps digital
channel. Sampling is done at 8Hz with 4 bits used to describe the difference
between adjacent samples.
Adaptive Pulse Code Modulation
- A technique that effectively reduces occupied bandwidth per active speaker by
reducing sampling rates during periods of overflow peak traffic.
A unique identity of each network station on a LAN or WAN.
- a bit mask used to identify which bits in an address (usually an IP address)
are network significant, subnet significant, and host significant portions of
the complete address. This mask is also known as the subnet mask because the
subnetwork portion of the address can be determined by comparing the binary
version of the mask to an IP address in that subnet. The mask holds the same
number of bits as the protocol address it references.
Address Prefix -
A string of 0 or more bits up to a maximum of 152 bits that is the lead portion
of one or more ATM addresses.
- The procedure by which a client associates a LAN destination with the ATM
address of another client or the BUS.
- The relationship between two communicating neighboring peer nodes.
ADTF (ACR Decrease Time Factor)
- For ABR, the time permitted between sending RM-cells before the rate is
decreased to the ICR (Initial Cell Rate of .01 to 10.23 seconds with .5 as the
AFI (Authority and Format Identifier)
- Identifies the format and type of address in use.
- a component of network- and desktop-management software, such as SNMP, that
gathers information from MIBs.
AHFG (ATM-attached Host Functional Group)
-The group of functions performed by an ATM-attached host that is participating
in the MPOA service.
AIM (ATM Inverse Multiplexer)
- A term discontinued because of conflict with an established product. Refer to
AIMUX (ATM Inverse Multiplexing)
- A device that allows multiple T1 or E1 communications facilities to be
combined into a single broadband facility for the transmission of ATM cells.
- Actual time spent talking on the cellular telephone.
AIS (Alarm Indication Signal)
- In T1, an all ones condition used to alert a receiver that its incoming
signal (or frame) has been lost. The loss of signal or frame is detected at the
receiving end, and the failed signal is replaced by all the ones condition
which the receiver interprets as an AIS. The normal response to this is AIS is
for the receiving end to generate a yellow alarm signal as part of its
transmission towards the faulty end. (The AIS itself is sometimes called a Blue
- an unsolicited message from a device, typically indicating a problem with the
system that requires attention.
Alarm or Indicator Fuse
- Type of fuse used on distribution and equipment frames used in parallel with
larger load fuses to indicate the operation of the load fuse.
- A location generally within a technical control facility that receives local
and remote alarms.
- Term used to describe equipment in a failed state.
- Attendant console indicators show the status of the telephone system. There
are usually two types of displays, minor and major. Minor displays are not
usually service affecting, while a major is, and requires immediate attention.
- A cable pair used to carry alarm circuits. For example, circuits from remote
pressure contactors to centrally located alarm equipment in a cable
- Relay which operates a circuit signaling an alarm.
- The PCM coding and companding standard used in Europe.
- A prescribed finite set of well defined rules or processes for the solution
of a problem in a finite number of steps. In normal English, it is the
mathematical formula for an operation, such as computing the check digits on
packets of data that travel via packet switched networks. In T-1, an
algorithm is a recipe for making a computer do
something. A sequence of steps followed by a computer to accomplish a task.
- A message or other type of readout containing both letters
(alphas) and numbers (numerics). In cellular,
alphanumeric memory dial is a special type of dial-from-memory
option that displays both the name of the individual and that individuals
phone number on the cellular phone handset. The name also can be recalled by
using the letters on the phone keypad. By contrast, standard memory dial
recalls numbers from number-only locations.
- A mechanism that supports the use of a new path after an attempt to set up a
connection along a previously selected path fails.
Alternating Current Generator
- An alternator; a rotating machine which produces an alternating current
- A generator that produces electric power in the form of alternating current
- Surrounding; often used as shorthand for surrounding air.
Ambient Noise Level
- The level of acoustic noise existing in a room or other location, as measured
with a sound level meter. It is usually measured in decibels above a reference
level of 0.00002 newton per square meter in SI units, or 0.0002 dyne per square
centimeter in cgs units.
- Temperature of surrounding fluid, air, or gas.
AMI (Alternate Mark Inversion) -
A line coding format used on T1 facilities that transmits ones by alternate
positive and negative pulses.
AMI (ATM Management Interface)
- the user interface to Marconi ForeThought switch control software (SCS). AMI
lets users monitor and change various operating configurations of Marconi
switches and network module hardware and software, IP connectivity, and SNMP
- Instrument which measures the amount of current in amperes flowing in a
- Abbreviated form of ampere.
- Current carrying capacity, expressed in amperes, of a wire or cable under
stated thermal conditions.
- The strength of an electric current in amperes.
- The amperage which may be safely applied to a circuit, service or equipment.
- A measure of electrical current intensity.
- When the current is one ampere, the quantity of electricity that flows in one
hour. Multiplying current in amperes by time of flow in hours equals ampere
hours. In this case, batteries are often rated over an eight-hour period.
- The traditional method of modulating radio signals so that they can carry
information. AM (amplitude modulation) and FM (frequency modulation) are the
two most common methods of analog modulation.
- A channel which transmits in analog waveforms.
- A simple computer-type device able to operate on analog inputs and produce
- A device which converts an Analog signal to a digital signal.
- An electrical signal that varies continuously over an infinite range of
voltage or current values, as opposed to a digital signal, which varies
discretely be-tween two values, usually one and zero. It is easiest to think of
analog signals as sine waves of various sizes.
- A continuously variable parameter.
- A logical group node that has a direct parent relationship to a given node
(i.e., it is the parent of that node, or the parent's parent.)
- Name given to the visual and audible portion of the alarm interface/isolation
facility which utilizes visual/audible panels throughout the telephone office.
ANSI (American National Standards Institute)
- a private organization that coordinates the setting and approval of some U.S.
standards. It also represents the United States to the International Standards
- A device for transmitting or receiving, or transmitting and receiving
signals. An antennas shape and size depends on what frequency and the
strength of the signal it is receiving.
- A self-supporting steel structure able to carry VHF or microwave antennae at
different heights above ground.
- Storage cell which utilizes lead-antimony alloy plates.
API (Application Program Interface)
- a language format that defines how a program can be made to interact with
another program, service, or other software; it allows users to develop custom
interfaces with Marconi products.
APP (application program)
- a complete, self-contained program that performs a specific function directly
for the user.
- A blank panel used to cover open equipment space in a rack or shelf.
A program designed to be executed from within another application. Unlike an
application, applets cannot be executed directly from the operating system. Web
browsers, which are often equipped with Java virtual machines, can interpret
applets from Web servers. Because applets are small in files size,
cross-platform compatible, and highly secure (can't be used to access users'
hard drives), they are ideal for small Internet applications accessible from a
- a networking protocol developed by Apple Computer for communication between
Apple's products and other computers. Independent of the network layer,
AppleTalk runs on LocalTalk, EtherTalk and TokenTalk.
Application Layer -
Layer seven of the ISO reference model; provides the actual end-user interface.
APS (Automatic Protection Switching)
- Equipment installed in communications systems to detect circuit failures and
automatically switch to redundant, standby equipment.
- Sustained luminous passage of current between contacts or electrodes.
ARP (Address Resolution Protocol)
- a method used to resolve higher level protocol addressing (such as IP) into
the appropriate header data required for ATM; i.e., port, VPI, and VCI; also
defines the AAL type to be used.
- A device used to protect equipment from lightning, electrical storms, etc.
ASCII (American Standard Code for Information Interchange)
- a standard character set that (typically) assigns a 7-bit sequence to each
letter, number, and selected control characters.
- a cell that provides a service to an upper layer entity or ATM Layer
Management entity (ATMM-entity).
- a Marconi program that repeatedly displays the state of the switch and of all
its active ports.
ATC (ATM Transfer Capability)
- Octet 5A in the BBC IE. The ATC is used to identify a sub category of ATM
service category. For example, ATC 5 represents a CBR Service Category with a
BCOB of X and requiring end-to-end timing.
ATDM (Asynchronous Time Division Multiplexing)
- a multiplexing technique in which a transmission capability is organized into
a priori, unassigned time slots. The time slots are assigned to cells upon
request of each application's instantaneous real need.
ATM (Asynchronous Transfer Mode)
- a transfer mode in which the information is organized into cells. It is
asynchronous in the sense that the recurrence of cells containing information
from an individual user is not necessarily periodic.
- Defined in the UNI Specification as 3 formats, each having 20 bytes in
ATM Anycast Capability
- The ability to allow an application to request a point-to-point connection to
a single ATM end system that is part of an ATM group.
- an international non-profit organization formed with the objective of
accelerating the use of ATM products and services through a rapid convergence
of interoperability specifications. In addition, the Forum promotes industry
cooperation and awareness.
- Refers to a PNNI (Private Network Node Interface or Private
Network-to-Network Interface) which has been standardized by the ATM Forum.
ATM Layer link
- a section of an ATM Layer connection between two adjacent active ATM Layer
- a virtual path link (VPL) or a virtual channel link (VCL).
ATM Peer-to-Peer Connection
- a virtual channel connection (VCC) or a virtual path connection (VPC)
directly established, such as workstation-to-workstation. This setup is not
commonly used in networks.
ATM Traffic Descriptor
- a generic list of parameters that can be used to capture the intrinsic
traffic characteristics of a requested ATM connection.
ATM User-to-User Connection
- an association established by the ATM Layer to support communication between
two or more ATM service users (i.e., between two or more next higher layer
entities or between two or more ATM entities). The communication over an ATM
Layer connection may be either bi-directional or unidirectional. The same
Virtual Channel Identifier (VCI) is used for both directions of a connection at
- a Marconi program that shows and manipulates ATM ARP entries maintained by
the given device driver. This is also used to establish PVC connections.
- a Marconi program used to enable or disable SPANS signaling.
- a Marconi program that shows statistics gathered about a given adapter card
by the device driver. These statistics include ATM layer and ATM adaptation
layer cell and error counts. This can also be used to query other hosts via
- The signal which rings the telephone set.
- An alarm panel usually equipped with audible, visual and alarm cut-off
AUI (Attachment User Interface)
- IEEE 802.3 interface between a media attachment unit (MAU) and a network
interface card (NIC). The term AUI can also refer to the rear panel port to
which an AUI cable might attach.
- a feature that automatically logs out a user if there has been no user
interface activity for a specified length of time.
- The process of compensating for distortion of data communications signals
over an analog circuit. With regard to battery systems, an automatic means to
raise the battery voltage slightly to equalize the voltage on all of the
Automatic Power Transfer
- Automatic transfer of a load from one power source to another, or to a
- Transformer in which both the primary and secondary currents flow through one
common part of the coil.
- An alternate source of electric power, serving as back-up for the primary
power at the station main bus or prescribed sub-bus.
AvCR (Available Cell Rate)
- Measure of effective available bandwidth. Available Cell Rate applies to all
service categories except UBR.
AW (Administrative Weight)
- The link or nodal-state parameter set by an administrator to indicate
AWG (American Wire Gauge)
- Measurement scale for non-ferrous (copper, bronze, etc.) wire.