Glossary 0-A0-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 | U-Z
- 10Base2: The IEEE
specification for thin Ethernet coaxial cable, also known as thinnet or
- 10Base5: An implementation of the Ethernet IEEE standard
on twinaxial cable, a baseband medium, at 10 megabits per second. The maximum
segment length is 500 meters.
- 10BaseF: The IEEE 802.3 standard for
Ethernet running over fiber. It includes subgroups 10BaseFB (synchronous fiber
serial chains repeaters) 10BaseFL (asynchronous fiber, inter operable with
FOIRL, greater link distances) 10BaseFP (asynchronous fiber & passive star
- 10BaseT: An IEEE 802.3 specification for Ethernet over
unshielded twisted pair cabling. Differs from the original Ethernet standard in
allowing a star topology rather than a linear bus. Devices can be located up to
100 meters from the concentrator/hub.
- 1Base5: An implementation of
the StarLAN IEEE standard on a baseband medium at 1 megabit per second. The
maximum segment length is 500 meters.
- A: See Ampere
- Abrasion Resistance: The Ability to Resist
- AC: See Alternating Current or Access Control
- Accelerated Aging: A test that
simulates long time environmental conditions in a relatively short
- Acceptable Use Policy: (AUP) This refers to
policies that restrict the way in which a network may be used. Usually, a
network administrator makes & enforces decisions dealing with acceptable
- Access Control: (AC) Contains a token
indicator & frame priority on token ring networks.
- Access Method: A
set of rules which the networks arbitrate their use.
- ACK: Short for
Acknowledgment. ACK is a data link control character sent upon receipt of an
error-free message. It is used to indicate that a message was received
- ACR: See Attenuation Crosstalk
- ACSE: See Association Control Service
- Active/Passive device: Active either amplifies the signal
or retransmits the signal, usually requiring external power. Passive lets the
signal go through, sometimes weakening it. Passive devices don't require any
- ACU: See Automatic Calling
- Adapter: A device that makes two non-matching pieces work
together; Power adapter for equipment that can't use the supply voltage.
Connector Adapters (SCSI, Phone, etc.) to match the port with the connector on
- Adapter Card: A printed circuit board
which is installed in a PC. It provides the communications interface to the
network. Also referred to as a NIM (Network Interface Module). See also NIC (Network Interface Card).
- ADC: See Advanced Data Communications
- Address: A unique
number identifying a node on a network. There are only two types of Addresses;
Hardware = OSI Layer 2 & Internet = OSI layer 3.
- Address Mask: The
address mask is used to identify the parts of an IP address that correspond to
the different sections (separated by dots). It's also known as the "subnet
mask" since the network portion of an address can be determined by the encoding
inherent in an IP address.
- Address Resolution: The process of
determining what LAN hardware address (level 2) corresponds to an Internet
Protocol address (level 3). Used by routers & hosts before transmitting a
packet on a LAN.
- Address Resolution Protocol: (ARP)
The data link layer protocol used by the IP layer of routers & hosts in a
TCP/IP network. It is used to determine a local hardware address of a node on a
directly attached LAN, given its IP address responds with its hardware
- Address Table: The list of host addresses & link numbers
maintained by a bridge to determine where to forward packets.
- Adjusted Ring Length: (ARL) In a multiple-wiring closet
ring, the adjusted ring length is the sum of all wiring closet-to-closet cables
in the main ring path less the length of the shortest of these cables, times
- Advanced Data Communications: (ADC) The USA
Federal Standard Communications Protocol.
Program-to-Program Communications: (APPC) Primarily for personal computers
in an SNA network to communicate with a mainframe host, this implementation of
LU 6.2 uses high-level program interaction.
Research Projects Agency: (ARPA) The Group Developed within the US
Department of Defense for research purposes.
Cable: Telecommunication cable installed on aerial supporting
- AF: See Audio Frequency
See AppleTalk Filing Protocol
- Agent: Part of a
system's software that performs information retrieval & exchange on behalf of a
client or server application.
- Air Core Cable: A cable in which the
interstices in the cable core are not filled with a moisture
- Alias: A type of nickname (usually short & easy to remember)
that refers to a type of network resource. Aliases are used so you won't have
to remember the long & difficult names typical of network
- Alpeth: Aluminum-polyethylene, the primary sheath for
- Alphanumeric: Describing a character set that contains
letters, numbers & other characters such as punctuation marks.
Routing: A method of completing connections that uses another path when the
primary circuit is unavailable, out of service, or busy.
- Alternating Current: (AC) An electric current that
periodically reverses direction of electron flow. The rate at which a full
cycle occurs in a given unit of time (generally a second) is called the
frequency of the current.
- Alvyn: Aluminum-polyvinyl-chloride, the
preferred sheath for riser cable where a flame-retardant sheath is required to
meet NEC standards.
- AM: See Amplitude
- Ambient Noise: The existing noise in a transmission
media. In telephone lines, this is usually heard as the background "hiss" & is
due to electrical signals traveling down the line. Also called "background" or
- American National Standards
Institute: (ANSI) A voluntary U.S. based organization which defines
standards for the information processing industry.
- American Society for Testing Materials: (ASTM) An
organization that tests materials & attempts to set standards on various
materials for the industry.
- American Standard Code for
Information Interchange: (ASCII) A seven-bit-plus-parity code established
by ANSI to achieve compatibility between data devices.
- American Wire Gauge: (AWG) A wire diameter specification.
The smaller the AWG number,. the larger the wire diameter
- Ampere: (A) A standard unit of current. Defined as the
amount of current that flows when one volt of EMF is applied across one ohm of
resistance. An ampere of current is produced by one coulomb of charge passing a
point in one second.
- Amplifier: Any electronic component that boosts
the strength or amplitude of a transmitted (usually analog) signal;
functionally equivalent to a repeater in digital
- Amplitude: The strength or magnitude of an analog
signal. On a waveform, amplitude is measured as the distance between the peak &
- Amplitude Modulation: (AM) One of three
basic ways to add information to a sine wave signal; the magnitude of the sine
wave, or carrier, is modified in accordance with the information to be
- Analog: Representation of data by variable
- Analog Recording: Transfer method that converts data from
digital to analog format.
- Anneal: To soften & relieve strains in any
solid material, such as metal or glass, by heating to just below its melting
point & then slowly cooling it. Annealing generally lowers the tensile strength
of the material, while improving its flex life & flexibility.
FTP: By using the word "anonymous" as your user ID & your e-mail address as
the password when you login to an FTP site, you can bypass local security
checks & gain limited access to public files on the remote computer. This type
of access is available on most FTP sites, but not all.
- ANSI: See American National Standards Institute
- API: See Application Program Interface
- APPC: See Advanced Program-to-Program
- AppleShare: Apple Computer's network system
implementing the AppleTalk protocols.
- AppleTalk: Protocol suite
defined by Apple Computer for connecting computers & peripherals using shielded
twisted-pair wiring & transfer rates of about 230.4 kilobytes per second. The
network- & transport-level protocols include Datagram Delivery Protocol (DDP)
AppleTalk Transaction Protocol (ATP) AppleTalk Session Protocol (ASP) & the
Name Binding Protocol (NBP)
- AppleTalk Filing
Protocol: (AFP) In an AppleTalk network, this link access-layer (or data
link-layer) protocol governs packet transmission on
- Application: Sometimes known as a client or an "app," it's
a program that performs a specific function. FTP, Mail, Gopher, Mosaic, &
Telnet clients are the most common examples of Internet
- Application layer: A term used in reference to Layer 7
of the OSI model. This layer provides the means to access application services
such as file-transfer, virtual-terminal functions, & electronic-mail
- Application Program: A program designed for a specific
- Application Program Interface: (API) A set of
formalized software calls & routines that can be referenced by an application
program to access underlying network services.
- Application Specific Integrated Circuit: (ASIC) Custom made
Integrated Circuits for specific applications, some of our switchboxes are
compact and use less power because they're built with an
- Archie: You'll usually hear this term referred to in the phrase
"archie search" Archie is a way of automatically gathering, indexing &
sometimes even retrieving files on the Internet. Most good archie clients are
able to FTP files once you've found the information you're looking
- Archive: A collection of files stored on an Internet machine.
FTP sites are known as archives.
- ARCnet: A 2.5 megabit per second
baseband, token-passing network designed by Datapoint Corporation that supports
up to 255 nodes.
- ARL: See Adjusted Ring
- Armored Cable: A cable provided with a wrapping of metal
for mechanical protection.
- ARP: See Address Resolution
- ARPA: See Advanced Research Projects
- ARPANET: The first major packet-switched
- ARQ: See Automatic Request for
- ASCII: See American Standard Code
for Information Interchange
- ASIC: See Application
Specific Integrated Circuit
- Association Control
Service Element: (ACSE) An application-level protocol.
- ASTM: See
American Society for Testing Materials An organization that
tests materials & attempts to set standards on various materials for the
- Asynchronous Transfer Mode: (ATM) A high
speed packet switching technology used to transmit video, data, voice, etc. via
fixed-length cells of 53bytes.
- Asynchronous Transmission: Data
transmission technique controlled by stop & start bits. Sending & receiving
DTE’s are not synchronized throughout the transmission.
- ATM: See Asynchronous Transfer Mode
- ATP: AppleTalk Transaction
- Attachment Unit Interface: (AUI) Used
with thick Ethernet often including drop cable & has a limit of 50 meters in
length. The drop cable is DB15 Male to Female.
- Attenuation: The power
loss in an electrical system, or in other words, loss of signal strength. Its
measurement is decibel/distance (typically dB/1,000 feet of dB/ft).
- Attenuation Crosstalk Radio: (ACR) The difference between
attenuation & crosstalk, measured in dB, at a given frequency
A term used to describe sounds within the range of human hearing. Also used to
describe devices which are designed to operate within this range.
- Audio Frequency: (AF) The range of frequencies lying within
the range of human hearing: approximately 20 to 20,000 Hz.
Trails: A record of events on the network including when users requested
- AUI Cable: See Attachment Unit
- AUP: See Acceptable Use
- Authentication: Any process that ensures that users are
who they say they are. When you type your name & password, you are
authenticated & allowed access.
- Automatic Calling
Unit: (ACU) The device attached to the sending DTE that facilitates dialing
of a receiving DTE. It automatically performs the dialing function eliminating
the need to manually dial the receiving DTE.
Request for Retransmission: (ARQ) A communications feature in which the
receiver asks the transmitter to resend a block or frame, generally because of
errors detected by the receiver.
- AWG: See American
- AWM: Appliance Wiring Material.