ADTRAN L128T user manual Telnet, Tcp/Ip, twisted pair, 2B+D, 23B+D, two-wire circuit

Glossary

Telnet

The TCP/IP standard protocol for remote terminal connection service. Telnet allows a user at one site to interact with a remote timesharing system at anoth- er site as if the user's terminal were connected directly to the remote machine.

TCP/IP

Transmission Control Protocol/Internet Protocol. A set of protocols devel- oped by the Department of Defense to link dissimilar computers across many kinds of networks.

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 thicknesses. 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.

2B+D

The Basic Rate Interface (BRI) in ISDN. A single ISDN circuit divided into two 64 kbps digital channels for voice or data and one 16 kbps channel for low speed data (up to 9,600 baud) and signalling. 2B+D is carried on one or two pairs of wires depending on the interface, the same wire pairs that today bring a single voice circuit into your home or office. See ISDN.

23B+D

In ISDN, also known as the Primary Rate Interface. A circuit with a wide range of frequencies that is divided in twenty-three 64 kbps paths for carrying voice, data, video, or other information simultaneously. It bears a remarkable similarity to today’s T1 link, except that T1 carries 24 voice channels. In ISDN, 23B+D gives twenty-three channels and one D channel for out-of-band signal- ling. However, in T1, signalling is handled in-band. See ISDN.

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 and one pair is used to receive. All trunk cir- cuits (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 of- fice to the subscriber’s phone system) are 2-wire, unless a 4-wire circuit is re- quested.

168 Express L128/L128T User Manual 61202.070L1-1