B0-A | B | C-Cn |
Co-Cz | D | E | F-G | H-I | J-L | M | N-O | P-Q | R | S | T | U-Z
B | C-Cn | Co-Cz | D | E | F-G | H-I | J-L | M | N-O | P-Q | R | S | T
- Back-end: Database Server for
- Backbone: A facility (pathway, cable or
conductors) between telecommunications closets, entrance facilities & equipment
rooms within or between buildings.
- Backbone Cabling: Cable &
connecting hardware that comprise the main & intermediate cross-connects as
well as cable runs that extend between telecommunications closets equipment
rooms & entrance facilities
- Backbone Raceway: That portion of the
pathway system that permits the placing of main or high-volume cables between
the entrance location & all cross-connect points within a building & between
- Backbone Segment: A single segment that is located on the
black plane of the network center hub.
- Backup: Off-line copies of
data for protection against system failures.
- Backup Path: The unused
pair of wires in the twisted pair cable used in a Token ring network. The
backup path is designed to enable the network to continue to operate while a
problem such as a faulty cable or MAU is being repaired.
Circuit: A circuit so arranged that the impressed voltages on each
conductor of the pair are equal in magnitude, but opposite in polarity with
respect to ground.
- Balanced Line: A cable having two identical
conductors which carry voltages opposite in polarity & equal in magnitude with
respect to ground.
- Balun: Derived from the terms “balanced” &
“unbalanced”. It is an adapter that converts an unbalanced signal, e.g. 93 ohm
coax to 100 ohm unshielded twisted pair.
- Band Marking: A continuous
circumferential band applied to a conductor at regular intervals for
- Bandwidth: The information carrying capacity of the
fiber. The bandwidth for a given wavelength is the lowest frequency at which
optical power has decreased by 3 dB, expressed in MHz-km. At frequencies higher
than the recommended bandwidth, modal dispersion creates distortion making
- Baseband: A transmission technique that allows
only one signal at a time to travel on a cable.
- Baud: The measurement
of signal changes per second. This is not necessarily equal to bits per second,
as one signal change may represent several bits (Baud is not an
- Baudot: Data-transmission code in which 5 bits represent 1
character. Letters or figure shifts enables 64 alphanumeric characters to be
represented. Baudot is used in many teleprinter systems, with one start bit &
1.5 stop bits added.
- Bayonet Neill-Corcelman: (BNC)
A coax connector that is locked on by a quarter turn. Typically used on
- BBS: See Bulletin Board
- BCC: See Block Check
- Bend Loss: Signal loss that occurs due to beams of
light escaping where the fiber is bent.
- Bend Radius: The smallest
bend a cable can withstand before the transmission is affected.
See Bit Error Rate
Internet Name Domain: (BIND) An early version of a DNS server developed by
University of California at Berkeley. Most Internet hosts run a version of
- Best Path: The optimal route through a wide area network.
Routers use a routing protocol to determine the best sequence of links each
packet should take in order to reach its destination with the lowest delay cost
or other criteria.
- Binary Numbering System: A two-state numbering
system (bi=2) Represented on paper as a sequence of 1's & 0's.
See Berkeley Internet Name Domain
- Binder: A tape
or thread used for holding assembled cable components in
- Bindery: NetWare database of user names, passwords, groups &
- Bisynchronous Transmission:
(BSC) A byte or character oriented IBM communications protocol that has become
an industry standard. It uses a defined set of control characters for
synchronized transmission of binary coded data between stations in a data
- Bit: A contraction of Binary digit. A BIT is
the smallest element of information in a digital system that can have a on
(yes) value or off (no) value.
- Bit Error Rate:
(BER) The ratio of received bits that are in error (relative to a specific
amount of bits received): usually expressed as a number referenced to a power
- Bitnet: A Computer network devoted to academic use that
provides e-mail & file transfer services using a store-and-forward protocol. It
is based on the IBM Network Job Entry protocols. A more recent version of
Bitnet (known as Bitnet-II) encapsulates the Bitnet protocol within OP
- Bits per second: (BPS) A term used to
express the speed at which bits can be transmitted.
- Block: A sequence
of continuous data transmitted as a unit. Sometimes referred to as transmission
- Block Check Character: (BCC) A bit pattern
attached to the end of a transmission block for error detection purposes. Used
primarily during synchronous transmission.
- Block Framing Character:
Characters used to mark the beginning & ending of a transmission
- BNC: See Bayonet
- Bonding: The permanent joining of metallic parts
to form an electrically conductive path which will assure electrical continuity
& the capacity to conduct safely any current likely to be imposed on
- Booster: A device or amplifier inserted into a line or cable to
increase the voltage or signal.
- Boot: A protective coating over a
cable; wire or connector in addition to the normal jacket or insulation or a
form placed around wire termination of a multi-contact connector to contain the
liquid potting compound before it hardens.
- Bounce: If you send e-mail
& it fails to arrive at its intended recipient for any reason (incorrect user
name, network failure, etc.), the message "bounces" & return to you. The
subject line in a bounced message usually says something like: "Undeliverable
mail" or "Message Undeliverable."
- bps: See Bits per
- Braid: A group of textile or metallic filaments interwoven
to form a tubular structure which may be applied over one or more wires, or
flattened to form a strap.
- Breakout: Multifiber cable constructed in
a tight buffered design. Designed for ease of connecting & rugged applications
for intra- or interbuilding requirements.
- Bridge: Used to connect two
separate local or remote networks of the same communication standard (i.e.
Ethernet to Ethernet or Token Ring to Token Ring).
- Broadband: A data
transmission technique allowing multiple high speed signals to share the
bandwidth of a single cable via frequency division
- Broadcast: A packet delivery system that allows all
host attached to the network to receive a copy of the sent
- Broadcast Domain: The complete set of uses to whom a
broadcast frame is transmitted to, from an indicated end station. The
boundaries of a broadcast domain are defined by routers.
Storm: A LAN software failure mode caused by many stations on the network
incorrectly replying to a broadcast packet with another broadcast packet. The
result is an extremely high traffic load. A broadcast storm is usually caused
by misconfigured network software.
- Brouters: A network device that
can perform the functions of both a bridge & a router.
- BSC: See Bisynchronous Transmission
- Buffer: A storage device.
Commonly used to compensate for the differences in data rates or even timing
when transmitting from one device to another. Also used to remove jitters. Or
on a fiber optic, a layer of material, usually thermoplastic, applied in
addition to the optical fiber coating, which provides protection from stress &
- Bulletin Board System: (BBS) A computer
that typically provides e-mail services, file archives, & announcements of
interest to the bulletin board system's operator (known as a sysop). BBSs
started out as hobbies for computer enthusiasts, & were mostly accessible by
modem. Recently, however, more & more BBSs are connecting to the
- Bunch Strand: Conductors twisted together with the same lay
& direction without regard to geometric pattern.
- Bundle (Fiber
Optic): A number of fibers grouped together, usually carrying a common
- Buried Cable: A cable installed directly in the earth without
the use of underground conduit. Also called "direct burial
- Bus: A LAN topology. All devices are linked in a string or
line (or hooked in series).
- Bus-bar Wire: Uninsulated tinned copper
wire used as a common lead.
- Butt Splice: A splice wherein two wires
from opposite ends butt against each other, or against a stop, in the center of
- Butyl Rubber: A synthetic rubber with good electrical
- Byte: A sequence or group of 8 bits. A byte
can represent one character or digit.