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PSOTEC ONLINE GLOSSARY
10Base2 - Ethernet specification for
thin coaxial cable, transmits signals at 10 Mbps (megabits per
second) with a distance limit of 185 meters per segment.
10Base5 - Ethernet specification for
thick coaxial cable, transmits signals at 10 Mbps (megabits per
second) with a distance limit of 500 meters per segment.
10BaseF - Ethernet specification for fiber optic
cable, transmits signals at 10 Mbps (megabits per second) with a
distance limit of 1000 meters per segment.
10BaseT - Ethernet specification for
unshielded twisted pair cable (category 3, 4, or 5), transmits
signals at 10 Mbps (megabits per second) with a distance limit of
100 meters per segment.
Access Method - Rules that govern how
nodes on a network access the cable.
AppleTalk - Apple Computer's
network protocol originally designed to run over LocalTalk
networks, but can also run on Ethernet and Token Ring.
AUI Connector (Attachment Unit Interface)
- A 15 pin connector found on Ethernet cards that can be used for
attaching coaxial, fiber optic, or twisted pair cable.
Backbone - A cable to which multiple
nodes or workstations are attached.
Bit - Binary digit in the binary
numbering system. Its value can be 0 or 1. In an 8-bit character
scheme, it takes 8 bits to make a byte (character) of data.
BNC Connector (Bayone-Neill-Concelman) -
Standard connector used to connect 10Base2 coaxial cable.
Bridge - Devices that connect and pass
packets between two network segments that use the same
communications protocol.
Cable - Transmission medium of copper
wire or optical fiber wrapped in a protective cover.
Client/Server - A networking system in
which one or more file servers (Server) provide services; such as
network management, application and centralized data storage for
workstations (Clients).
CSMA/CA - Carrier Sense Multiple Access Collision
Avoidance is a network access method in which each device signals
its intent to transmit before it actually does so. This prevents
other devices from sending information, thus preventing
collisions from occurring between signals from two or more
devices. This is the access method used by LocalTalk.
CSMA/CD - Carrier Sense Multiple
Access Collision Detection is a network access method in which
devices that are ready to transmit data first check the channel
for a carrier. If no carrier is sensed, a device can transmit. If
two devices transmit at once, a collision occurs and each
computer backs off and waits a random amount of time before
attempting to retransmit. This is the access method used by
Ethernet.
Coaxial Cable - Cable consisting of a
single copper conductor in the center surrounded by a plastic
layer for insulation and a braided metal outer shield.
Concentrator - A device that
provides a central connection point for cables from workstations,
servers, and peripherals. Most concentrators contain the ability
to amplify the electrical signal they receive.
Dumb Terminal - Refers to devices that
are designed to communicate exclusively with a host (main frame)
computer. It receives all screen layouts from the host computer
and sends all keyboard entry to the host. It cannot function
without the host computer.
E-Mail - An electronic mail message
sent from a host computer to a remote computer.
End User - Refers to the human
executing applications on the workstation.
Ethernet - A network protocol
invented by Xerox Corporation and developed jointly by Xerox,
Intel and Digital Equipment Corporation. Ethernet networks use
CSMA/CD and run over a variety of cable types at 10 Mbps
(megabits per second).
Expansion Slot - Area in a computer
that accepts additional input/output boards to increase the
capability of the computer.
Fast Ethernet - A new Ethernet standard that
supports 100 Mbps using category 5 twisted pair or fiber optic
cable.
Fiber Optic Cable - A cable, consisting
of a center glass core surrounded by layers of plastic, that
transmits data using light rather than electricity. It has the
ability to carry more information over much longer distances.
File Server - A computer connected
to the network that contains primary files/applications and
shares them as requested with the other computers on the network.
If the file server is dedicated for that purpose only, it is
connected to a client/server network. An example of a
client/server network is Novell Netware. All the computers
connected to a peer-to-peer network are capable of being the file
server. Two examples of peer-to-peer networks are LANtastic and
Windows for Workgroups.
Gigabyte (GB) - One billion bytes of
information. One thousand megabytes.
Hub - A hardware device that contains
multiple independent but connected modules of network and
internetwork equipment. Hubs can be active (where they repeat
signals sent through them) or passive (where they do not repeat
but merely split signals sent through them).
Infrared - Electromagnetic waves
whose frequency range is above that of microwaves, but below that
of the visible spectrum.
Internet - A global network of
networks used to exchange information using the TCP/IP protocol.
It allows for electronic mail and the accessing and retrieval of
information from remote sources.
LAN (Local Area Network) - A network connecting
computers in a relatively small area such as a building.
Linear Bus - A network topology in
which each node attaches directly to a common cable.
LocalTalk - Apple Corporation
proprietary protocol that uses CSMA/CA media access scheme and
supports transmissions at speeds of 230 Kbps (Kilobits per
second).
MAN (Metropolitan Area Network) - A network
connecting computers over a large geographical area, such as a
city or school district.
MAU (Multistation Access Unit) - A Token
Ring wiring hub.
Modem (Modulator/Demodulator) - Devices
that convert digital and analog signals. Modems allow computer
data (digital) to be transmitted over voice-grade telephone lines
(analog).
Multiplexer - A device that
allows multiple logical signals to be transmitted simultaneously
across a single physical channel.
Network Modem - A modem connected to
a Local Area Network (LAN) that is accessible from any
workstation on the network.
Network Interface Card (NIC) - A board
that provides network communication capabilities to and from a
computer.
Network Operating System (NOS) -
Operating system designed to pass information and communicate
between more than one computer. Examples include AppleShare,
Novell NetWare, and Windows NT Server.
Node - End point of a network
connection. Nodes include any device attached to a network such
as file servers, printers, or workstations.
Node Devices - Any computer or
peripheral that is connected to the network.
PCMCIA - An expansion slot found in
many laptop computers.
Peer-to-Peer Network - A network in
which resources and files are shared without a centralized
management source.
Physical Topology - The
physical layout of the network; how the cables are arranged; and
how the computers are connected.
Point-to-Point - A direct link
between two objects in a network.
Ports - A connection point for a cable.
Protocol -A formal description of a
set of rules and conventions that govern how devices on a network
exchange information.
RAID (Redundant Array of Inexpensive
Disks) - A configuration of multiple disks designed to preserve
data after a disk casualty.
RAM (Random Access Memory) - The working
memory of a computer where data and programs are temporarily
stored. RAM only holds information when the computer is on.
Repeater - A device used in a
network to strengthen a signal as it is passed along the network
cable.
RJ-45 - Standard connectors used for
unshielded twisted-pair cable.
Router -A device that routes
information between interconnected networks. It can select the
best path to route a message, as well as translate information
from one network to another. It is similar to a superintelligent
bridge.
Segment - Refers to a section of
cable on a network. In Ethernet networks, two types of segments
are defined. A populated or trunk segment is a network cable that
has one or more nodes attached to it. A link segment is a cable
that connects a computer to an interconnecting device, such as a
repeater or concentrator, or connects a interconnecting device to
another interconnecting device.
Sneaker-Net - Refers to a manual
method of sharing files in which a file is copied from a computer
to a floppy disk, transported to a second computer by a person
physically walking (apparently wearing sneakers) to the second
computer, and manually transferring the file from floppy disk to
the second computer.
Speed of Data Transfer
- The rate at which information travels through a network,
usually measured in megabits per second.
Star Topology - LAN topology in which
each node on a network is connected directly to a central network
hub or concentrator.
Star-Wired Ring - Network
topology that connects network devices (such as computers and
printers) in a complete circle.
Tape Back-Up - Copying all the
data and programs of a computer system on magnetic tape. On tape,
data is stored sequentially. When retrieving data, the tape is
searched from the beginning of tape until the data is found.
Terminator - A device that
provides electrical resistance at the end of a transmission line.
Its function is to absorb signals on the line, thereby keeping
them from bouncing back and being received again by the network.
Token - A special packet that contains
data and acts as a messenger or carrier between each computer and
device on a ring topology. Each computer must wait for the
messenger to stop at its node before it can send data over the
network.
Token Ring - A network protocol
developed by IBM in which computers access the network through
token-passing. Usually uses a star-wired ring topology.
Transceiver
(Transmitter/Receiver) - A Device that receives and sends signals
over a medium. In networks, it is generally used to allow for the
connection between two different types of cable connectors, such
as AUI and RJ-45.
Tree Topology - LAN topology
similar to linear bus topology, except that tree networks can
contain branches with multiple nodes.
Twisted Pair - Network cabling that
consists of four pairs of wires that are manufactured with the
wires twisted to certain specifications. Available in shielded
and unshielded versions.
WAN (Wide Area Network) - A network connecting
computers within very large areas, such as states, countries, and
the world.
Workgroup - A collection of
workstations and servers on a LAN that are designated to
communicate and exchange data with one another.
Workstation - A computer
connected to a network at which users interact with software
stored on the network.
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