Glossary
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
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.
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TCP/IP: A set of communication protocols that support
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
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
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
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
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
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
Transport Layer: Layer 4 of the Open Systems Interconnection (OSI) model; provides reliable,
Transport Protocol Data Unit (TPDU): A transport header, which is added to every message, contains destination and source addressing information that allows the
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
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