Multi-Tech Systems MT4X56USB - Manual (Page 82)

MultiModemUSB User Guide
MT4X56USB 82
Congestion: A network condition where there is too much data traffic. The ITU I.233 standard defines congestion
managemennt in terms of speed and burstiness.
Congestion notification: The function in frame relay that ensures that user data transmitted at a rate higher than the CIR
are allowed to slow down to the rate of the available network bandwidth.
Consecutive Severely Errored Seconds (CSES): An error condition that occurs when from 3 to 9 SES (Severely Errored
Seconds) are logged consecutively.
Customer Premise Equipment (CPE): The generic term for data comm and/or terminal equipment that resides at the user
site and is owned by the user with the following exclusions: Over voltage protection equipment, inside wiring, coin operated
or pay telephones, “company-official” equipment, mobile telephone equipment, “911” equipment, equipment necessary for
the provision of communications for national defense, or multiplexing equipment used to deliver multiple channels to the
customer.
D
Data Communications Equipment (DCE): Any device which serves as the portal of entry from the user equipment to a
telecommunications facility. A modem is a DCE for the telephone network (PSTN) that is commonly on site at the user’s
premises. Packet Switched Networks have another level of DCE which is most often located at a central office.
Data Link Connection Identifier (DLCI): One of the six components of a frame relay frame. Its purpose is to distinguish
separate virtual circuits across each access connection. Data coming into a frame relay node is thus allowed to be sent
across the interface to the specified “address”. The DLCI is confirmed and relayed to its destination, or if the specification is
in error, the frame is discarded.
Dataphone Digital Service (DDS): A private line digital service that offers 2400, 4800, 9600 and 56 Kbps data rates on an
inter-LATA basis by AT&T and on an intra-LATA basis by the BOCs.
Data Service Unit (DSU): A device that provides a digital data service interface directly to the data terminal equipment. The
DSU provides loop equalization, remote and local testing capabilities, and a standard EIA/CCITT interface.
Dedicated Line: A communication line that is not switched. The term leased line is more common.
Default: This is a preset value or option in software packages, or in hardware configuration, that is used unless you specify
otherwise.
Default Address: an address defined by the Universal Serial Bus Specification and used by a Universal Serial Bus device
when it is first powered or reset. The default address is 00h.
Default Pipe: the message pipe created by Universal Serial Bus system software to pass control and status information
between the host and a Universal Serial Bus device’s Endpoint 0.
Device: a logical or physical entity that performs a function. The actual entity described depends on the context of the
reference. At the lowest level, device may refer to a single hardware component, as in a memory device. At a higher level, it
may refer to a collection of hardware components that perform a particular function, such as a Universal Serial Bus
interface device. At an even higher level, device may refer to the function performed by an entity attached to the Universal
Serial Bus; for example, a data/FAX modem device. Devices may be physical, electrical, addressable, and logical. When
used as a non-specific reference, a Universal Serial Bus device is either a hub or a function.
Device Address: the address of a device on the Universal Serial Bus. The Device Address is the Default Address when the
Universal Serial Bus device is first powered or reset. Hubs and functions are assigned a unique Device Address by
Universal Serial Bus software.
Device driver: Software that controls how a computer communicates with a device, such as a printer or mouse.
Digital Cross-connect System (DCS): The CO device which splits and redistributes the T1 bandwidth. the DCS takes time
slots from various T1 lines and alters them to provide the needed connectivity. DCS connections are made with software at
an administrator’s workstation.
Digital Data: Information represented by discrete values or conditions (contrast “Analog Data”).
Digital Loopback: A technique used for testing the circuitry of a communications device. Can be initiated locally, or
remotely (via a telecommunications device). The tested device decodes and encodes a received test message, then echoes
the message back. The results are compared with the original message to determine if corruption occurred en route.
Digital PBX: A Private Branch Exchange that operates internally on digital signals. See also “Exchange”.
Digital Service, level 0 (DS0): The world-wide standard speed (64 Kbps) for digital voice conversation using PCM (pulse
coded modulation).
Digital Service, level 1 (DS1): The 1.544M bps voice standard (derived from an older Bell System standard) for digitized
voice transmission in North America. The 1.544M bps consists of 24 digitally-encoded 64 Kbps voice channels (north
America) and 2.048M bps (30 channels) elsewhere.