Multi-Tech Systems MULTIMODEM MT5634ZPX-V.92-ISA - Manual (Page 37)

Glossary
37
MultiModemZPX User Guide
business PABX or any residential phone connects to the PSTN
at a central office.
Centrex: A multi-line service offered by operating telcos which
provides, from the telco CO, functions and features comparable
to those of a PBX for large business users. See also “Private
Branch Exchange”, “Exchange”.
Channel: A data communications path between two computer
devices. Can refer to a physical medium (e.g., UTP or coax), or
to a specific carrier frequency.
Channel Bank: A device that acts as a converter, taking the
digital signal from the T1 line into a phone system and
converting it to the analog signals used by the phone system. A
channel bank acts as a multiplexer, placing many slow-speed
voice or data transactions on a single high-speed link.
Characteristics: Those qualities of a Universal Serial Bus
device that are unchangeable; for example, the device class is a
device characteristic.
Circuit-switched Network: A technology used by the PSTN
that allocates a pair of conductors for the exclusive use of one
communication path. Circuit switching allows multiple
conversations on one talk path only if the end-users multiplex
the signals prior to transmission.
Circuit Switching: The temporary connection of two or more
communications channels using a fixed, non-shareable path
through the network. Users have full use of the circuit until the
connection is terminated.
Clear Channel: A transmission path where the full bandwidth is
used (i.e., no bandwidth needed for signaling, carrier framing or
control bits). A 64 Kbps digital circuit usually has 8 Kbps used
for signaling. ISDN has two 64 Kbps circuits, and a 16 Kbps
packet service of which part is used for signaling on the 64K
channels.
Client-Server: In TCP/IP, the model of interaction in distributed
data processing in which a program at one site sends a request
to a program at another site and awaits a response. The
requesting program is called a client; the answering program is
called a server.
Cluster Controller: A device that can control the input/output
operations of more than one device connected to it. A cluster
controller may be controlled by a program stored and executed
in the unit, or it may be entirely controlled by hardware.
Committed Burst Size: The maximum number of bits that the
frame relay network agrees to transfer during any measurement
interval.
Committed Information Rate (CIR): An agreement a customer
makes to use a certain minimum data transmission rate (in
bps). The CIR is part of the frame relay service monthly billing,
along with actual usage, that users pay to their frame relay
service provider.
Compression: 1. The process of eliminating gaps, empty fields,
redundancies, and unnecessary data to shorten the length of
records or blocks. 2. In SNA, the replacement of a string of up
to 64-repeated characters by an encoded control byte to reduce
the length of the data stream to the LU-LU session partner. The
encoded control byte is followed by the character that was
repeated (unless that character is the prime compression
character). 3. In Data Facility Hierarchical Storage Manager, the
process of moving data instead of allocated space during
migration and recall in order to release unused space. 4.
Contrast with decompression.
COMx Port: A serial communications port on a PC.
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