Multitech MultiModem MT5634ZPX User Manual page 59

Switched Network: A network in which a temporary connection is
established from one point via one or amore segments.
Synchronous Data Link Control (SDLC): A discipline conforming
to subsets of the Advanced Data Communications Control
Procedures (ADCCP) of the American National Standards Institute
(ANSI) and High-level Data Link Control (HDLC) of the
International Organization for Standardization, for managing
synchronous, code-transparent, serial-by-bit information transfer
over a link connection. Transmission exchanges may be duplex, or
half-duplex over switched or nonswitched links. The configuration
of the link connection may be point-to-point, multipoint, or loop.
Synchronous Transmission: The transmission of data which
involves sending a group of characters in a packet. This is a
common method of transmission between computers on a network
or between modems. One or more synchronous characters are
transmitted to confirm clocking before each packet of data is
transmitted. Compare to Asynchronous Transmission.
Systems Network Architecture (SNA): The description of the
logical structure, formats, protocols, and operational sequences
for transmitting information units through, and controlling the
configuration and operation of, networks.
T
TCP/IP: A set of communication protocols that support peer-to-
peer connectivity functions for both local and wide area networks.
T Carrier: The generic name for a digitally multiplexed carrier
system. In the North American digital hierarchy, a T is used to
designate a DS (digital signal) level hierarchy. Examples: T1 (DS1)
is a 1.544 M bps 24-channel designation. In Europe, T1 is called
E1. The T Carrier system was originally designed for transmitting
digitized voice signals, but has since been adapted for digital data
applications.
T1: A digital transmission link capable of 1.544M bps. T1 uses two
pairs of normal UTP, and can handle 24 voice conversations, each
digitized at 64 Kbps. T1 is a standard for digital transmission in the
U.S., Canada, Japan and Hong Kong. T1 is the access method for
high-speed services such as ATM, frame relay, and SMDS. See
also T Carrier, T1 line and FT1.
T1 Channel Tests: A set of diagnostics that vary by carrier, used
to verify a T1 channel operation. Can include Tone, Noise Level,
Impulse Noise Level, Echo Cancelers, Gain, and Crosstalk testing.
T1 Framing: To digitize and encode analog voice signals requires
8000 samples per second (twice the highest voice frequency of
4000 Hz). Encoding in an 8-bit word provides the basic T1 block of
64 Kbps for voice transmission. This "Level 0 Signal, as its called,
is represented by "DS-0", or Digital Signal at Level 0. 24 of these
voice channels are combined into a serial bit stream (using TDM),
on a frame-by-frame basis. A frame is a sample of all 24 channels;
so adding in a framing bit gives a block of 193 bits (24x8+1=193).
Frames are transmitted at 8000 per second (the required sample
rate), creating a 1.544M (8000x193=1.544M) transmission rate.
T1 Line: A digital communications facility that functions as a 24-
channel pathway for data or voice transmission. A T1 line is
composed of two separate elements: the Access element and the
Long Haul element.
T1 Mux: A device used to carry many sources of data on a T1 line.
The T1 mux assigns each data source to distinct DS0 time slots
within the T1 signal. Wide bandwidth signals take more than one
time slot. Normal voice traffic or 56/64 Kbps data channels take
one time slot. The T1 mux may use an internal or external T1
DSU; a "channel bank" device typically uses an external T1 CSU.
Transmission Control Protocol / Internet Program (TCP/IP): A
multi-layer set of protocols developed by the US Department of
Defense to link dissimilar computers across dissimilar and
unreliable LANs.
Multi-Tech Systems, Inc. MT5634ZPX User Guide
Terminal: The screen and keyboard device used in a mainframe
environment for interactive data entry. Terminals have no "box",
which is to say they have no file storage or processing capabilities.
Terminal Adapter (TA): An ISDN DTE device for connecting a
non-ISDN terminal device to the ISDN network. Similar to a
protocol converter or an interface converter, a TA connects a non-
ISDN device between the R and S interfaces. Typically a PC card.
Tie line: A dedicated circuit linking two points without having to
dial a phone number (i.e., the line may be accessed by lifting the
telephone handset or by pushing a button).
Time-Division Multiplexing (TDM): Division of a transmission
facility into two or more channels by allotting the common channel
to several different information channels, one at a time.
Time Slot: One of 24 channels within a T1 line. Each channel has
a 64 Kbps maximum bandwidth. "Time slot" implies the time
division multiplexing organization of the T1 signal.
Toll Call: A call to a location outside of your local service area
(i.e., a long distance call).
Tone dialing: One of two methods of dialing a telephone, usually
associated with Touch-Tone® (push button) phones. Compare with
pulse dialing.
Topology: Physical layout of network components (cables,
stations, gateways, and hubs). Three basic interconnection
topologies are star, ring, and bus networks.
Transmission Control Protocol (TCP): A communications
protocol used in Internet and in any network that follows the US
Department of Defense standards for internetwork protocol. TCP
provides a reliable host-to-host protocol between hosts in packet-
switched communications networks and in interconnected systems
of such networks. It assumes that the Internet protocol is the
underlying protocol.
Transport Layer: Layer 4 of the Open Systems Interconnection
(OSI) model; provides reliable, end-to-end delivery of data, and
detects transmission sequential errors.
Transport Protocol Data Unit (TPDU): A transport header, which
is added to every message, contains destination and source
addressing information that allows the end-to-end routing of
messages in multi-layer NAC networks of high complexity. They
are automatically added to messages as they enter the network
and can be stripped off before being passed to the host or another
device that does not support TPDU's.
Trunk: Transmission links that interconnect switching offices.
TSR (terminate and stay resident): A software program that
remains active and in memory after its user interface is closed.
Similar to a daemon in UNIX environments.
Tunneling: Encapsulation data in an IP packet for transport
across the Internet.
Twisted pair wiring: A type of cabling with one or more pairs of
insulated wires wrapped around each other. An inexpensive wiring
method used for LAN and telephone applications, also called UTP
wiring.
Type A: The upstream (USB Type A) connector. A Type A
Connector is for those devices on which the external cable is
permanently attached. Connectors for USB come in two designs:
the 'A' and 'B' types. Upstream connections (computer, hub input,
etc.) are made using the 'A' type connector, downstream
connections (peripherals, hub outputs) are made using the 'B' type
connector. The USB spec defines two types of connectors to
protect the bus from illegal topologies (e.g., connecting one
downstream port back to another, etc.) and to prevent end-user
confusion. This allows end users to easily attach the correct
connectors to peripherals and ports. Type A Plug and receptacle
are to be used for those devices on which the external cable is
permanently attached to devices such as Keyboard, mouse and
hubs. Series B Plug and receptacle are to be used for those
devices that require an external detachable cable such as printers,
scanners and modems.
Glossary
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