access method
The way in which data may pass onto a physical network medium.

active star
Star topology with active hubs.

address
The unique identifier for the source or destination of a data transfer.

ANSI
American National Standards Institute. US standards-setting body and member organization if ISO and IEC.

application layer
Highest layer of the OSI Model where user and application interface.

ARP
Address Resolution Protocol. TCP/IP protocol which maps IP addresses to those of Ethernet or some other system.

ATM
Asynchronous Transfer Mode. High bandwidth and low overhead networking system using something akin to packet-switching. It is the future of high-speed broadband networks.

AUI
Attachment Unit Interface. Transceiver for thick Ethernet systems.

backbone
A segment of a network that connects LANs together. Often fiber optic cabling is used for this purpose.

bandwidth
The range of electrical frequencies that a device or medium can support.

baseband
A type of system where only digital data is carried on the transfer medium.

BNC
Bayonet-Neill-Concelman. A type of twist-locking connector used with coaxial cable.

BPS
Bits Per Second. A measure of data transfer speed.

Bridge
A network device that links similar or dissimilar LANs at the data link layer.

broadband
A system carrying many different types or channels of data by dividing the total bandwidth of the medium into smaller bandwidths.

bus topology
A physical layout of network devices in which all devices must share a common medium to transfer data, and no two devices may transmit simultaneously.

coaxial cable
Metal cabling constructed such that one conductor serves as a shielding for the other. Insulation separates the two conductors and the shielding is coated by plastic for protection. Can carry lots of data, but is more expensive than twisted pair cabling.

collision
When electrical signals from two or more devices sharing a common data transfer medium crash into one another. this commonly happens on Ethernet-type systems.

concentrator
A device that joins several communication channels together.

connectivity
The attachment of devices on a network. The devices may be similar or dissimilar.

contention
In reference to Ethernet-type systems. Devices contend for single data channel.

counter-rotating ring
Technology used in FDDI to provide fault-tolerance.

CRC
Cyclical Redundancy Check. Used like checksum to detect errors in data transmissions.

CSMA CA or CD
Carrier Sense Multiple Access with Collision Avoidance or Collision Detection. Methodology in which Ethernet systems allow devices to check for signals on the common medium and prevent collisions. Apple uses collision avoidance techniques while IEEE 802.3 specifies collision detection techniques.
data link layer
The second layer of the OSI Model that allows messages to be placed into packets and vice-versa. It controls data flow.

datagram
A TCP/IP packet containing data and a source and destination address. It uses an unreliable delivery method.

DCE
Data Communications Equipment or Data Circuit-terminating Equipment. Technical term for a modem. Device that establishes, maintains and destroys a session on a network.

duplex
Simultaneous two-way transmission of data. (Also referred to as full duplex.)

EMI
Electromagnetic Interference.

emulation
Act like something else. An example would be when a PC appears to be a dumb terminal to a host.

enterprise network
A network comprised of all the LANs or other networks within a single organization.

FDDI
Fiber Distributed Data Interface. Fiber standard that uses only an iota of fiber's throughput capacity.

fiber optic cable
Cabling that carries light instead of electrons. Capable of enormous bandwidth. Usually made with glass.

frame
A block of data in bit-oriented protocols.

FTP
File Transfer Protocol.

full duplex
Describes the simultaneous two-way flow of data.

gateway
A device or software that allows communication between dissimilar networks such as PC and mainframe networks.

GHz
Gigahertz.

half duplex
Describes transmissions where data only travels in one direction at any given moment.

hub
The central device of a star topology.

IEEE
Institute of Electronic and Electrical Engineers. Developers of numerous standards regarding electronics.

internetwork
A combination of multiple networks joined together through connecting devices (i.e. bridges, routers).

IP
Internet Protocol. TCP/IP's connectionless, unacknowledged protocol.

LAN
Local Area Network. A group of connected computers and other peripheral devices in a limited geographical area under some controlling entity like a network OS.

LLC
Logical Link Control.

MAC
Media Access Control.

Mbps
Megabits per second.

network
A collection of computer-related devices interconnected under some form of common control.

NIC
Network Interface Card. Provides the physical means of gaining access to a network from a computer or network peripheral.

node
A network device of some sort.

noise
Non-data signals that can disrupt clean data communications.

OSI
Open System Interconnection. Standards promulgated by ISO including the well-known OSI Model.

packet
A collection of data into a form that is transmitted as a discrete unit over a network communication channel.

protocol
A formal set of specifications detailing data communication. Often used to refer to types of packets.

repeater
A device for regenerating a signal that has attenuated due to distance limitations. Works on the physical layer.

SAP
Service Access Point. The point at which processes on certain layers of the OSI Model access data from other layers.

session
A logical relationship or connection set up between two nodes that wish to communicate with one another.

simplex
A system in which data only travels in one direction.
SNMP

Simple Network Management Protocol.

SONET
Synchronous Optical NETwork. Part of the ISDN system. Allows broadband transmission over fiber optic cable at throughputs ranging from 51 Mbps to over 13 Gbps.

store-and -forward
A description given to message-switching networks.

STP
Shielded Twisted Pair.

T connector
A special connector used in bus systems that allow attachment of coax cable to a network node or a terminator.

TCP
TCP/IP packet protocol providing connection-oriented reliable delivery.

TCP/IP
Transmission Control Protocol / Internet Protocol. Protocols developed for use on the Internet.

terminator
A device on a bus topology system that absorbs used data off of the LAN so it does not echo back and cause collisions.

throughput
The measure of how much data travels from one point to another in a given time frame. Usually represented in bits per second.

topology
Describes the physical or logical layout of a network.

TP
Twisted Pair.

twisted pair cable
A type of cabling containing pairs of wires twisted around each other to provide resistance to crosstalk and external interference.

UTP
Unshielded Twisted Pair.

Fast and Gigabit Ethernet Glossary