ADTRAN 4200659L2 User Manual
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Appendix D Glossary

10BaseT

Ethernet connector which implements the IEEE standard on 24-gauge,unshieldedtwisted-pairwiring.

AMI

Alternate mark inversion. A bipolar line-codingformat in T1 transmission systems whereby successive ones are alternately inverted.

ANSI

American National Standards Institute. A non-profitorganization that coordinates voluntary standards activities in the United States.

asynchronous

A method of data transmission which allows characters to be sent at irregular intervals by preceding each character with a start bit, followed by a stop bit.

bandwidth

The bandwidth determines the rate at which information can be sent through a channel (the greater the bandwidth, the more information that can be sent in a given amount of time).

baud rate

A measure of transmission speed over an analog phone line. Baud rate measures the shortest signaling elements per second in the analog signal that a modem sends over an analog phone line. Does not necessarily equal the bit rate.

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Appendix D. Glossary

BERT

Bit error rate test. A test that uses any of a number of stress patterns to test T3, T1, FT1, and DDS circuits.

bipolar

A signal containing both positive and negative amplitude components.

bipolar violation

See BPV.

bit

A binary digit representing a signal, wave, or state as either a one or a zero. A bit is the smallest unit of information a computer can process.

bit error

The receipt of an encoded bit that differs from what was sent by the transmitter.

bit rate

The speed at which bits are transmitted, usually expressed in bits per second (bps).

bps

Bits per second. The number of bits passing a specific point per second. Examples of common rates are kbps (one thousand bits per second) and Mbps (one million bits per second). T3 operates at 44.736 Mbps.

BPV

Bipolar violation. A violation in the alternate mark inversion (AMI) line code for which consecutive 1s are represented by pulses of opposite polarity. BPVs that are not intentional (B8ZS) are counted as errors. Could also be the presence of two consecutive 1 bits of the same polarity on the T-carrierline.

bridge

A data communications device that connects two or more networks and forwards packets between them.

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Appendix D. Glossary

byte

Generally, an 8-bitquantity of information. This term is used mainly in referring to parallel data transfer, semiconductor capacity, and data storage.

carrier

The provider of the telecommunication services to the customer site. Carriers can be local telephone companies, regional telephone companies, or any interexchange carrier such as AT&T, Sprint, or MCI.

C-bit

An overhead bit in the DS3 string not used for framing, parity, or alarm indication.

CCITT

Consultive Committee for International Telephony and Telegraphy. A standards organization that devises and proposes recommendations for international communications. See also ANSI.

CD

Carrier detect. A signal generated by a modem or DSU/CSU indicating the presence of a carrier signal on a communications link.

channel

A transmission path between two or more termination points; also called a circuit, facility, line, link, or path.

channel bank

Equipment in a telephone central office or customer premises that performs multiplexing of lower speed digital channels into a higher speed composite channel. The channel bank also detects and transmits signaling information for each channel, thereby transmitting framing information so that time slots allocated to each channel can be identified by the receiver.

channel service unit

See CSU.

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Appendix D. Glossary

clocking

An oscillator-generatedsignal that provides a timing reference for a transmission link. A clock provides signals used in a transmission system to control the timing of certain functions. The clock has two functions: (1) to generate periodic signals for synchronization, and (2) to provide a time base.

CPE

Customer premises equipment. All telecommunications terminal equipment located on the customer premises, including telephone sets, private branch exchanges (PBXs), data terminals, and customer-owned, coin-operatedtelephones.

craft port

The electrical interface between the MX2800 STS-1and the control terminal. The control terminal is used to communicate commands to the unit.

CSU

Channel service unit. A device used to connect a digital phone line coming in from the phone company to either a multiplexer, channel bank, or directly to another device producing a digital signal; for example, a digital PBX, a PC, or data communications device. A CSU performs certain line-conditioningand equalization functions, and responds to loopback commands sent from the central office. A CSU also regenerates digital signals. It monitors them for problems and provides a way of testing the digital circuit.

CTS

Clear to send. A signal on the DTE interface indicating that the DCE is clear to send data.

data communications equipment

See DCE.

data service unit

See DSU.

dB

Decibel. A unit of measure of signal strength; usually the relation between a transmitted signal and a standard signal source.

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Appendix D. Glossary

DCE

Data communications equipment. Device that provides all the functions required for connection to telephone company lines and for converting signals between telephone lines and DTE. Also see DTE.

DDS

Digital data service. A private line digital service for transmitting data end-to-endat speeds of 2.4, 4.8, 9.6, and 56 kbps (and in some cases 19.2, 38.4, or 64 kbps). The systems can use central hub offices for obtaining test access, bridging legs ofmulti-pointcircuits, and cross connecting equipment. DDS is offered on aninter-LATA(local access and transport area) basis by AT&T and on anintra-LATAbasis by the Bell operating companies.

delay

The amount of time by which a signal is delayed. A round-triptransmission delay measurement helps detect possible causes of protocol timeouts.

DLCI

Datalink communications identifier. A unique number assigned to a PVC endpoint in a frame relay network. Identifies a particular PVC endpoint within a user's access channel in a frame relay network and has local significance only to that channel.

DS1

Digital signal level one. Twenty-fourDS0 channels make up one DS1 (total bandwidth is 1.544 Mbps).

DS3

Digital signal level three. Equivalent of 28 DS1s and 672 DS0s (total bandwidth is 44.736 Mbps).

DSR

Data set ready. A signal on the DTE interface that indicates if a connection exists and if the devices are ready to start handshaking control signals so communications can begin.

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Appendix D. Glossary

DSU

Data service unit. A device designed to transmit and receive digital data on digital transmission facilities.

DTE

Data terminal equipment. The end-userterminal or computer that plugs into the termination point (DCE) of a communications circuit. The main difference between the DCE and the DTE is that pins two and three are reversed.

E1

Transmission rates of 2.048 Mbps are available on T1 communication lines. See also T1.

end device

The ultimate source or destination of data flowing through a network (sometimes referred to as DTE).

end user

Subscriber who uses (rather than provides) telecommunications services.

ES

Errored seconds. A second with one or more coding violations (CVs).

ethernet

Transmission protocol for packet-switchingLANs.

facilities

The equipment used by carriers to provide communication services.

far end

The distant end to that being considered. Not the end where testing is being carried out.

FCC

Federal Communications Commission. The U.S. federal agency responsible for regulating interstate and international communications by radio, TV, wire, satellite, and cable.

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Appendix D. Glossary

FDL

Facility datalink. FDL bits provide overhead communication between the terminal equipment in ESF framing.

gateway

A device which enables information to be exchanged between two dissimilar systems or networks.

host computer

The primary or controlling computer in a multiple computer operation.

idle code

In a T3 circuit, an idle code consists of a sequence of 1100 over the entire payload bandwidth.

in-band

Signaling (dialing, diagnostics, management, configuration, etc.) over the same channel used for data.

IP

Internet protocol. A protocol which provides for transmitting blocks of data between hosts identified by fixed-lengthaddresses.

LAN

Local area network. A privately owned network that offers high-speedcommunications channels to connect information processing equipment in a limited geographic area.

local loopback (LL)

A type of test used to verify the operation of the local terminal equipment, the CSU, and the connection between the two. The signal from the DTE is looped back by the CSU and is sent back to the DTE.

loopback

The technique for testing the processing circuitry of a communications device. May be initiated locally or remotely via a telecommunications circuit. Device being tested will echo back received test data. The results are compared with the original data.

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Appendix D. Glossary

LOS

Loss of signal. Defined as a line state in which no pulses are received for 175 bit positions.

M13

DS1/DS3 multiplexer that combines up to 28 DS1 channels into one DS3 channel. Uses two-stage,bit synchronous TDM.

Mbps

Megabits per second (one million bits per second).

MIB

Management information base. A database of network management information used by SNMP.

modem

Acronym for modulator/demodulator. Equipment that converts digital signals to and from analog signals. Used to send digital signals over analog phone lines.

monitor

To watch or listen to a signal non-intrusively.

multi-pointcircuit

A single communications circuit that has more than two terminations.

NC

Normally closed. Relay switch contacts that remain closed when inactive.

near end

The unit on-site.

NI

Network interface. The demarcation point between the CPE and the PSTN.

NO

Normally open. Relay switch contacts that remain open when inactive.

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Appendix D. Glossary

NRZ

Non return to zero. A mode in which the digital level is low for a 0 bit and high for a 1 bit, and does not return to zero between successive 1 bits.

out-of-band

Signaling that is separated from the channel carrying information (voice, data, video, etc.). Typically the separation is accomplished by a filter. The signaling includes dialing and other supervisory signals.

point-to-point

Type of communications link that connects a single device to another single device, such as a remote terminal to a host computer.

POP

Point of presence. Physical place within a LATA (local access and transport area) where a long distance carrier or a cellular provider interfaces with the network of the local exchange carrier (LEC). A POP is usually a building serving as the point of termination which houses switches and transmission equipment.

protocol

A set of rules controlling the orderly exchange of information between stations in data communications networks or systems.

PSTN

Public switched telephone network. Usually refers to the world-widevoice telephone network available for public use.

red alarm

Unframed all ones signal (keep alive signal). A red alarm is declared on detection of LOS or OOF not caused by an alarm indication signal (AIS) that persists for more than two seconds.

remote configuration

A feature designed into ADTRAN products that allows remote units to be configured from a local unit or a VT 100 compatible terminal.

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Appendix D. Glossary

router

A device that supports communications between networks. Routers are similar to bridges, with the exception that routers provide more functionality (such as finding the best route between networks and providing network management capabilities).

service

The provision of telecommunications to customers by a common carrier, administration, or private operating agency using voice, data, and/or video technologies.

service provider

A company that delivers or sells a telecom service.

SES

Severely errored seconds. A second in which more than 320 code violations (CVs) occurred or an OOF condition occurred.

signaling

Communication between switches to set up and terminate calls.

SNMP

Simple network management protocol. A control and reporting scheme widely used to manage devices from different vendors. SNMP operates on top of the Internet protocol.

SONET

Synchronous optical network. A standard format for transporting a wide range of digital telecommunications services over optical fiber. SONET is characterized by standard line rates, optical interfaces, and signal formats.

synchronous

Communications in which the timing is achieved by sharing a single clock. Each end of the transmission synchronizes itself with the use of clocks and information sent along with the transmitted data.

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Appendix D. Glossary

T1

Transmission rates of 1.544 Mbps are available on T1 communication lines. Also referred to as digital signal level 1 (DS-1).See alsoE1.

T3

Transmission rates of 44.736 Mbps are available on T3 communication lines. Also referred to as digital signal level 3 (DS-3).

TDM

Time division multiplexing. A technique for transmitting two or more signals at the same time over a single communication medium. This is accomplished by allocating channels to the bandwidth for specific increments of time.

Telnet

The standard TCP/IP remote login protocol specified in RFC-854.

transceiver

A combination of transmitter and receiver providing both output and input interfaces within a single device.

transmission

The signaling of data over telecommunications channels.

V.35

A standard for trunk interface between a network access device and a packet network that defines signaling for data rates greater than 19.2 kbps.

VT-100

A non-intelligentterminal or terminal emulation mode used for asynchronous communications. Used to configure the MX2800STS-1.

WAN

Wide area network. A communications network serving geographically separate areas. A WAN typically extends a LAN outside the building to link to other LANs over telephone lines.

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Appendix D. Glossary

yellow alarm

A T3 yellow alarm is an indication sent back toward the source of a failed transmit circuit in a DS3 two-waytransmission path. TheX-bits(X1 and X2) are set to zero.

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