(We wish to thank Unicom for their contributions.)
10Base-2* – A variant of Ethernet, connecting stations via thin coaxial cable; maximum cable distance in one non-repeated segment is 185 meters.
10Base-5* – A variant of Ethernet, connecting stations via thick coaxial cable; maximum cable distance in one non-repeated segment is 500 meters.
10Base-FL* – A variant of Ethernet, connecting stations via fiber optic cabling.
10Base-T* – A variant of Ethernet, connecting stations via twisted pair cabling.
100Base-FX* – A variant of Ethernet which runs on multi-mode or single mode fiber optic cabling at 100 Mbps. This is one version of Fast Ethernet.
100Base-TX* – A variant of Ethernet which runs on Category 5 unshielded twisted pair wiring at 100 Mbps. This is one version of Fast Ethernet.
1000Base-CX* – A variant of Gigabit Ethernet which runs on twinaxial cable.
1000Base-LX* – A variant of Gigabit Ethernet which runs on multi-mode and single mode fiber optic cable at a 1330 µm frequency.
1000Base-SX* – A variant of Gigabit Ethernet which runs on multi-mode fiber optic cable at an 850 nm frequency.
1000Base-T* – A variant of Gigabit Ethernet which runs on unshielded twisted pair cable.
Abrasion Resistance – Ability of a wire, cable or material to resist surface wear.
Accelerated Aging – A test in which voltage, temperature, etc., are increased above normal operating values to obtain observable deterioration in a relatively short period of time. the plotted results give expected service life under normal conditions.
ACR (Attenuation to Crosstalk Ratio)* – The difference between attenuation and crosstalk measured in decibels.
Address* – A number uniquely identifying each node in a network.
Admittance – The measure of the ease with which an alternating current flows in a circuit. The reciprocal of impedance.
Aerial Cable – A cable suspended in the air on poles or other overhead structure.
Air Spaced Coaxial Cable – One in which air is the essential dielectric material. A spirally wound synthetic filament or spacer may be used to center the conductor.
Alloy – A metal formed by combining two or more different metals to obtain desirable properties.
Alternating Current – Electric current that continually reverses its direction. It is expressed in cycles per second (hertz or HZ).
Ambient Temperature – The temperature of a medium (gas or liquid) surrounding an object.
American Wire Gauge (AWG) – A standard system for designing wire diameter. Also referred to as the Brown and Sharpe (B & S) wire guard.
Ampere (unit of current) – One ampere is the current flowing through on ohm of resistance at one volt potential.
Amplitude* – In communications, the distance between the highest and lowest points in a wave. The amplitude controls the strength, or volume, of the signal.
Anneal – Relief of mechanical stress through head and gradual cooling. Annealing copper renders it less brittle.
ANSI (American National Standards Institute)* – A U.S. standards body. ANSI is a member of the International Organization for Standardization (ISO).
Armor – A braid or wrapping of metal, usually steel, used for mechanical protection. Generally placed over the outer sheath.
ASTM – Abbreviation for the American Society for Testing and Materials, a nonprofit industry wide organization which publishes standards, methods of test, recommended practices, definitions, and other related material.
ATM (Asynchronous Transfer Mode )* – A high-speed, connection-oriented switching and multiplexing technology for transmitting information across a wide area or local area network. ATM divides information into fixed-length cells capable of transmitting different types of traffic simultaneously, including voice, video, and data.
Attenuation* – The progressive weakening of a signal as it travels away from its point of origin.
Audio Frequency – The range of frequencies audible to the human ear. Usually 20-20,000HZ.
AUI (Attachment Unit Interface)* – Defined in the IEEE 802.1 specification as the interface between an Ethernet MAU and DTE. Basically, the way an Ethernet station connects to a transceiver sitting on a thick Ethernet cable.
Auto-Negotiation (N-Way)* – A mechanism that controls the data when a connection is established to a network device. It automatically switches to the correct technology in the following sequence:
- 100Base-TX, Full Duplex
- 10Base-T, Full Duplex
With the following benefits:
- Automatic Connection
- Backward Compatibility
- Network Protection
- Technology Extension
- Path Upgrade
- Management Interface
- Proprietary Extension
AWG (American Wire Gauge)* – A standard for determining wire size. The gauge varies inversely with the actual wire diameter.
AWM – Designation for appliance wiring material.
Backbone* – LAN or WAN connectivity between subnets across a high-speed network. Often applied to a high-speed campus network, such as ATM OC-12 or Gigabit Ethernet, that interconnects lower speed networks, such as ATM OC-3 or Fast Ethernet. Fiber optic cable is often used.
Balance* – An indication of signal voltage equality and phase polarity on a conductor pair. Perfect balance occurs when the signals across a twisted-pair are equal in magnitude and opposite in phase with respect to ground.
Balanced Signal Transmission* – Two voltages, equal and opposite in phase with respect to each other, across the conductors of a twisted-pair
Balun* – Balanced/unbalanced. An impedance matching device used to connect balanced twisted pair cabling with unbalanced coaxial cable.
Bandwidth* – (1) The range of signal frequencies that can be carried on a communications channel. The capacity of a channel is measured in cycles per second, or hertz (Hz), between the highest and lowest frequencies. (2) Commonly, the carrying capacity of a digital translation facility, measured in bits per second (bps).
Baseband* – A technique whereby digital input is directly applied to transmission media without the intervention of a modulating device. Baseband is generally applied in an environment with high bandwidth over a short distance. It is generally considered easier and more cost-effective than broadband. Ethernet, token ring, FDDI, and ATM generally use baseband.
Bend Loss* – Increased attenuation in a fiber that results from the fibers being bent, or from minute distortions within the fiber.
Bit* – A contraction of Binary Digit. The smallest unit of digital information.
Bit Rate (BR)* – The rate of data throughput on the medium in bits per second. Ethernet specifies 10 million bits per second.
Bit Time* – The duration of one bit symbol (1/BR). Ethernet specifies a bit time of 100 ns.
BNC Connector* – A specific type of connector used for coaxial RG58 cable connection.
Bonding* – The permanent joining of metallic parts to form an electrically conductive path that will assure electrical continuity and the capacity to conduct safely any current likely to be imposed on it.
bps (Bits per second)* – The amount of data transferred in a second.
Braid – A fibrous or metallic group of filaments interwoven in cylindrical form to form a covering over one or more wires.
Braid Angle – The smaller of the two angles formed by the shielding strand and the axis of the cable being shielded.
Braid Carrier – A spool or bobbin on a braider which holds one group of strands or filaments consisting of a specific number of ends. The carrier revolves during braiding operations.
Braid Ends – The number of strands used to make up one carrier. The strands are wound side by side on the carrier bobbin and lie parallel in the finished braid.
Breakdown Voltage – The voltage at which the insulation between two conductors breaks down.
Bridged Tap* – The multiple appearances of the same cable pair or fiber at several distribution points.
Bridging* – A means of providing through connections between conductors or pairs that are terminated on connecting blocks. These through connections are commonly provided by means of individual metallic “bridging” clips or multiple “bridging” clips that are housed in a plastic insulator.
Broadband* – Characteristic of any network that multiplexes multiple, independent carrier signals onto a single cable. This is usually accomplished through frequency division multiplexing. Broadband technology allows several signals to coexist on a single cable; traffic from one signal does not interfere with traffic from another, since data is transmitted on a different frequency. Cable television uses broadband.
Buffer* – A block of storage used to hold a portion of an information packet.
Bunch Stranding – A group of wires of the same diameter twisted together without a predetermined pattern.
Bundled Cable* – An assembly of two or more cables continuously bound together to form a single unit prior to installation.
Buried Cable – A cable installed directly in the earth without use of underground conduit. Also called “direct burial cable”
Bus (linear bus)* – A network topology in which all computers are connected by a single length of cabling with a terminator at each end.
Bus topology* – A network structure in which the signals sent by one device are received by all other devices. Each device then selects those transmissions addressed to it based on address information contained in the transmission.