Glossary Section "T" ( Definitions )
digital communications were introduced in the early 1960s to reduce
the amount of copper cable needed to carry the same number of telephone
conversations as analog communications. The term T1 circuit is commonly used to
identify a multiplexed 24 channel, 1.544 Mbps digital data circuit providing
communications between two facilities or from a local service provider. T1
refers to the transport of a DS-1 formatted signal onto a copper, fiber or
wireless medium for deploying voice, data or video-conferencing services. The T1
is part of an extensive digital hierarchy that starts with 24 DS0s at 64 kbps.
These individual DS0s are used to provide voice or digital data to support point
to point or network applications. By combining multiple DS0s, a high-speed
interface can be provided to support a synchronous interface to a LAN router or
voice PBX. See also international E1 equivalent.
TAA Trade Agreements Act (19 U.S.C. & 2 501-2581), requires that the U.S. Government purchase products made in the U.S.A. or specifically designated countries.
TCM Trellis Coded Modulation
TCO Total Cost of Ownership
TDM Time division multiplexing. The multiplexing technique used with multi-channel muxed modems.
TEl Terminal Equipment Type 1. ISDN-compatible terminals.
Telco Telephone Company
TERENA Trans-European Research and Education Networking Association.
TETRA Terrestrial Trunked Radio is a digital trunked mobile radio standard developed by the European Telecommunications Standards Institute ( ETSI )
TFTP Trivial File Transfer Protocol, is a simple form of the File Transfer Protocol (FTP) often used by boot diskless workstations, X-terminals, and routers. TFTP uses the User Datagram Protocol (UDP)and provides no security features.
TIP Terminal Interface Message Processor. This historic term refers to the nodes in the original ARPANET that had the capability to service terminals directly, allowing users to gain access to ARPANET hosts. A TIP was basically an IMP with a special terminal interface. TIPs later evolved to TACs.
TLD Top Level Domain.
topology A network topology shows the computers and the links between them. A network layer protocol must stay abreast of the current network topology to be able to route packets to their final destination.
TN3270 A variant of the Telnet program that allows one to attach to IBM mainframes and use the mainframe as if you had a 3270 or similar terminal.
traceroute A program available on many systems which traces the path a packet takes to a destination. It is mostly used to debug routing problems between hosts. There is also a traceroute protocol defined in RFC 1393.
transceiver Transmitter-receiver. The physical device that connects a host interface to a local area network, such as Ethernet. Ethernet transceivers contain electronics that apply signals to the cable and sense collisions.
twinax A type of cabling with 2 conductor wires, common with some IBM equipment.
twisted pair Two wires twisted around each other to reduce induction (interference) from one wire to the other. Several sets of twisted pair wires may be enclosed in a single cable. Twisted pair is the normal cabling from a central office to your home or office, or from your PBX to your office phone. Twisted pair wiring comes in various thickneses. As a general rule, the thicker the cable is, the better the quality of the conversation and the longer cable can be and still get acceptable conversation quality. However, the thicker it is, the more it costs.
two-wire circuit A transmission circuit composed of two wires, signal and ground, used to both send and receive information. In contrast, a 4-wire circuit consists of two pairs. One pair is used to send. One pair is used to receive. All trunk circuits (long distance) are 4-wire. A 4-wire circuit delivers better reception, but also costs more. All local loop circuits (those coming from a Class 5 central office to the subscribers phone system) are 2-wire, unless a 4-wire circuit is requested