Networking Glossary

ATM
Asynchronous Transfer Mode. Under ATM, multiple traffic types (such as voice, video, or data) are conveyed in fixed-length cells (rather than the random-length "packets" moved by technologies such as Ethernet and FDDI). This enables very high speeds, making ATM popular for demanding network backbones. With networking equipment that has recently become available, ATM will also support WAN transmissions. This feature makes ATM valuable for large, dispersed organizations.

Backbone
The part of a network that acts as the primary path for traffic moving between, rather than within, networks.

Bandwidth
The "data-carrying" capacity of a network connection, used as an indication of speed. For example, an Ethernet link is capable of moving 10 million bits of data per second. A Fast Ethernet link can move 100 million bits of data per second – 10 times more bandwidth.

Bridge
A device that passes packets between multiple network segments using the same communications protocol. If a packet is destined for a user within the sender’s own network segment, the bridge keeps the packet local. If the packet is bound for another segment, the passes the packet onto the network backbone.

Client
A networked PC or terminal that shares "services" with other PCs. These services are stored on or administered by a server.

Ethernet
A popular LAN technology that uses CSMA/CD (collision detection) to move packets between workstations and runs over a variety of cable types at 10 Mbps. Also called 10BaseT.

Extranet
A network that provides access to company documents such as price lists, inventory reports, shipping schedules and more to external users -- such as your suppliers, independent sales agents and dealers.

Fast Ethernet
Uses the same transmission method as 10-Mbps Ethernet (collision detection) but operates at 100 Mbps – 10 times faster. Fast Ethernet provides a smooth upgrade path for increasing performance in congested Ethernet networks, because it uses the same cabling, applications and network management tools. Variations include 100Base-FX, 100Base-T4 and 100Base-TX.

FDDI
Fiber Distributed Data Interface. A LAN technology based on a 100-Mbps token-passing network running over fiber-optic cable. Usually reserved for network backbones in larger organizations.

Frame Relay
Wide area network service that provides switched ("on-and-off") connections between distant locations.

FTP
File Transfer Protocol. A part of the chief Internet protocol "stack" or group (TCP/IP), used for transferring files from Internet servers to your computer.

HTML
hypertext markup language. Simple document formatting language used for preparing documents to be viewed by a tool such as a worldwide web browser.

HTTP
hypertext transmission protocol. Protocol that governs transmission of formatted documents over the Internet.

Hub
A device that interconnects clients and servers, repeating (or amplifying) the signals between them. Hubs act as wiring "concentrators" in networks based on star topologies (rather than bus topologies, in which computers are daisy-chained together).

Internet
A massive global network, interconnecting tens of thousands of computers and networks worldwide and accessible from any computer with a modem or router connection and the appropriate software.

Intranet
An internal network that leverages some of the same tools popularized on the Internet (browsers for viewing material, HTML for preparing company directories or announcement, etc.).

ISDN
Integrated Services Digital Network. Communication protocol offered by telephone companies that permits high-speed connections between computers and network in dispersed locations.

LAN
Local Area Network. Typically, a network or group of network segments confined to one building or a campus. Compare to WAN.

Modem
Device that enables a computer to connect to other computers and networks using ordinary phone lines. Modems "modulate" the computer’s digital signals into analog signals for transmission, then "demodulate" those analog signals back into digital language that the computer on the other end can understand.

Packet
A block of data with a "header" attached that can indicate what the packet contains and where it is headed. Think of a packet as a "data envelope," with the header acting as an address.

Remote Access Server
Device that handles multiple incoming calls from remote users who need access to central network resources. A remote access server can allow users to dial into a network using a single phone number. The server then finds an open channel and makes a connection without returning a busy signal.

Router
Device that moves data between different network segments and can look into a packet header to determine the best path for the packet to travel. Routers can connect network segments that use different protocols. They also allow all users in a network to share a single connection to the Internet or a WAN.

Server
A computer or even a software program that provides services to clients – such as file storage (file server), programs (application server), printer sharing (print server), fax (fax server) or modem sharing (modem server). See also client.

Switch
A device that improves network performance by segmenting the network and reducing competition for bandwidth. When a switch port receives data packets, it forwards those packets only to the appropriate port for the intended recipient. This further reduces competition for bandwidth between the clients, servers or workgroups connected to each switch port.

Token Ring
LAN technology in which packets are conveyed between network end stations by a token moving continuously around a closed ring between all the stations. Runs at 4 or 16 Mbps.