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Technical Glossary C - E

Communication Ports - Paths into or out of a computer that provide the means to link the computer with external devices, such as terminals and printers.

Control - A DSU or modem that is, for diagnostic purposes, at the logical head of an hierarchical network. There is only one control per link.

Control Channel (CC) - The diagnostic interface between the NMS and DSUs or modems.

Crosstalk - Line distortion caused by wire pairs in the same bundle being used for separate signal transmission.

CSA - Carrier Serving Area.

CSU - Channel Service Unit. A digital interface unit that connects service user equipment to the local digital telephone loop.

Customer Premises Equipment (CPE) - Any equipment such as telephones, computers, printers, video codec equipment, or other items that a user can connect to a network.

D4 Format - A TI transmission standard that specifies 12 frames as a superframe, and specifies the order of alignment and signaling bits in the frames.

Data Communications Equipment (DCE) - A device, such as a DSU or modem, that provides an interface between a DTE device and a digital or dial network (also called data circuit-terminating equipment).

Data Service Unit (DSU) - A customer premises device that is used to interface to a digital circuit (DDS or T I when combined with a CSU). The DSU performs conversion of a customer's data stream to bipolar format for transmission.

Data Terminal Equipment (DTE) - A computer or peripheral device at the end of the network, such as a PC, terminal, printer, data source, sink, etc.

DBM - Acronym for the Dial Backup Module option for the Model 3611, 355 1, and 3616 DSUs. This module is a pair of childboards that attach to the DSU circuit card to provide an alternate data path via a point-to-point telephone call.

DECNET - Digital Equipment Corporation's proprietary network architecture.

DHCP - Dynamic Host Configuration Protocol. A TCP/IP protocol that provides static and dynamic address management.

Digital Data Service (DDS) - A service that provides digital (not analog) communication circuits and supports speeds up to 56 Kbps; for example, DATAPHONE Digital Service or the ACCUNET Spectrum of Digital Services.

Diagnostic Channel (DC) - A digital interface between a DSU and a modem, used to extend the NMS diagnostics to the DSU via the modem.

Digital Access and Cross-Connect System (DACS) - A piece of equipment usually operated by a telephone company and controlled by an external computer that can cross-connect any TI line attached to the DACS to any other TI line, or any DSO channel or group of channels on a TI line to any DSO Time Slots of any other TI line.

Digital Signal - A signal that varies only at regular time intervals and has one, two, or more predetermined amplitudes for each interval.

DLC - Digital Loop Carrier. Network transmission equipment, consisting of a CO terminal and a remote terminal, used to provide a pair gain function.

DLCI - Data Link Connection Identifier. The virtual circuit number corresponding to a particular connection between two destinations. This number is used as part of the frame relay header.

DMT - Discrete MultiTone. DSL technology using digital signal processors to divide the signal into 256 subchannels.

Downstream - Refers to the transmission direction from the CO to the customer premises.

DRAM - Dynamic Random Access Memory. Used to store data in PCs and other devices.

DSL - Digital Subscriber Line. The non-loaded, local-loop copper connection between the Network Service Provider and the customer premises. DSL can provide simultaneous high-speed digital data access and POTS service over the same twisted-pair wiring.

DSLAM - Digital Subscriber Line Access Multiplexer. A platform for DSL modems that provides high-speed data transmission and optional POTS service simultaneously over traditional twisted-pair wiring.

DSP - Digital Signal Processor. The microprocessor that handles line signaling in a modem.

DSU - Digital Service Unit. Data communications equipment that transmits digital data over a private line.

DSX-1 - Digital Signal Cross-Connect Level 1. Refers to the standard DS I signal level at the cross-connection patch panel.

DSO - Digital Signal Level 0. A telephony term for a 64Kbps standard digital telecommunications signal or channel.

DTE - Data Terminal Equipment. The equipment, such as a computer or terminal, that provides data in the form of digital signals for transmission.

E1- A wideband digital interface operating at 2.048 Mbps, as defined by the ITU recommendations G.703 and G.704. Generally available outside North America.

EIA/TIA - Electronic Industries Association/ Telecommunications Industry Association. This organization provides standards for the data communications industry to ensure uniformity of the interface between DTEs and DCEs.

E&M Signaling - A method by which signaling information is communicated over two wires or leads that are separate from the analog signal path. Signaling information is sent on the M lead (remembered as "mouth") and received on the E lead (remembered as "ear"). An E&M port interface in a T I mux converts the M lead into transmitted signaling bits and coverts received signaling bits into the E lead.



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