Network Glossary

Here's a bit of advice... forget the thousands of acronyms, terms and standards this industry has spawned, and concentrate instead on the theory of how networks work. If you get in a pinch with jargon, the following glossary should help get you by.

A-C | D-F | G-I | J-L | M-O | P-R | S-U | V-Z

10BASE-T: The IEEE 802.3i standard specification for 10 Megabits per second (Mbps) Ethernet transmission over Unshielded Twisted Pair (UTP) wiring, using a star configuration with a hub at the center.

100BASE-T: The IEEE 802.3u standard Ethernet specification for 100Mbps (Fast Ethernet) transmission using UTP cable.



Adapter: The device that connects a piece of equipment to the network and controls the electrical protocol for communication with that network; also called network interface card, or NIC.

Adaptive Technology: An Intel technology (supported in adapters and switches) that automatically and dynamically customizes product performance to match network operating conditions, thus helping to optimize network performance.

ATM (Asynchronous Transfer Mode): A high-speed networking technology that transfers packets of data to transmit various kinds of information (voice, video, data).

Backbone: The part of the network that carries the heaviest traffic; it connects LANs, either within a building or across a city or region.

Bandwidth: The maximum amount of data that a network cable can carry, measured in bits per second (bps).

Baseband: A network transmission technique that uses voltage to represent data; similar to turning a light switch on and off.

Bridge: A device that connects two networks at the OSI Data Link layer and passes data between them; equivalent to a two-port switch.

Broadband: A network transmission technique that uses radio frequencies on a cable; a broadband cable is typically shared with other networks or services, such as TV or teleconferencing.

Browser: Client software used to search information posted on the Web; Netscape* and Microsoft Internet Explorer* are the most popular browsers.

Bus topology: The physical layout of a network in which all systems connect to a main cable; also known as linear bus.

Client: In a client/server network, a node (or user workstation) on the network that uses resources provided by a server.

Coaxial cable: A network cable with good noise immunity; also known as coax or thicknet.

Collision Domain: The maximum length of the wiring media that allows collision detection. For example, the collision domain in Fast Ethernet using 100BASE-TX is 205 meters.

CSMA/CD: The acronym for Carrier Sense Multiple Access with Collision Detection; a LAN transmission technique implemented in Layer 2 of the OSI model and employed by 10Mbps Ethernet and Fast Ethernet.



Dumb terminal: A monitor and keyboard that displays information only (as opposed to the processing capability of a PC); usually connected to a mainframe.

Fast Ethernet: The high-bandwidth networking technology based on the 802.3 Ethernet standard (100BASE-T); supports 100Mbps performance, a tenfold increase over original 10Mbps Ethernet (10BASE-T).

FDDI: The acronym for Fiber Distributed Data Interface; a standard for fiber optic cable.

Fiber optic: A cable that uses light to communicate; the fastest and most noise-resistant cable available for network wiring, but also the most expensive.

Frame relay: A high-speed, low-latency packet switching technology, based on a switched virtual network topology, used for WANs; popular for LAN-to-LAN connections.

Full-duplex: Allows a packet to be transmitted and received at the same time.



Gateway: A network station used to interconnect two or more dissimilar networks or devices; may perform protocol conversion.

Gigabit Ethernet: A developing technology for 1 gigabit per second (1Gbps) Ethernet; equivalent to 1000Mbps and 10 times faster than Fast Ethernet.

Half-duplex: Allows packets to be either transmitted or received, but not both at the same time.

Home page: The main page of a Web site and the first screen that a visitor sees displayed when connecting to that site; usually has links to other pages, both within that site and to other sites.

HTML: HyperText Markup Language, the authoring language of the Internet; used to create Web pages.

Hyperlinks: Embedded "hot spots" in Web pages that allow users to jump from one document to another related document, regardless of where it "lives" on the Internet.

Hub: The central wiring concentrator in a star-configured network; useful for centralized management, the ability to isolate nodes from disruption and extending the distance of LAN coverage.

IEEE: The Institute of Electrical and Electronics Engineers, a body that defines standards and specifications.

IP: Internet Protocol, the part of TCP/IP that governs packet forwarding.

IPX: Internet Packet Exchange, a NetWare protocol that provides connectionless communications between devices on a network.

ISDN: Integrated Services Digital Network, a telecommunications standard for sending digitized voice, video and data signals over the existing public switched telephone network.

ISO: International Standards Organization, a body that promotes computer standards and developed the OSI's model for network communication.



Local: Typically refers to devices attached to the user's workstation, as opposed to remote devices that are accessed through a server.

Local Area Network (LAN): Workstations and computers that are tied together in a specific work area in the same general location.



MAC: Media Access Control, the IEEE specification for the lower sublayer of the OSI Data Link layer; CSMA/CD and Token Ring are types of MACs.

MAC address: Unique address assigned to each active infrastructure end station (including adapters, LAN on motherboard, switch ports and router ports).

MDI (Medium Dependent Interface): The predefined physical layer interface for 10Mbps Ethernet.

MIB (Management Information Base): A database of objects that stores information used by SNMP-enabled management devices.

MII (Medium Independent Interface): The predefined physical layer interface for 100BASE-T.

Network Operating System (NOS): Software that manages the resources of a network; typically provides file sharing, e-mail, print services, security measures, etc.

NIC: A Network Interface Card; see adapter.

Node: Each of the individual computers or other devices on the network.

OSI: Open System Interconnection, a LAN communication model developed by ISO.



Packet: A chunk of data bits and associated information, including source address and destination address, formatted for transmitting from one node to another.

Packet analyzer: A network diagnostic tool that hooks into a LAN and analyzes its traffic; capable of capturing a packet, examining it and breaking it down into its component parts of destination, origin, protocol, data, etc.

Print server: An application-specific computer that manages printers and requests for print services; allows multiple users to share a network printer.

Print spooler: A software application, typically installed on a LAN server, that manages multiple print requests.

Protocol: Any defined set of procedures, conventions or methods that, when adhered to, allow two devices to interoperate; used to implement LAN services.

Remote execution: The ability to run programs on remote systems; exporting time-consuming processes to other systems frees up the local workstation.

Repeater: A device that regenerates and amplifies signals to create long-distance networks.

Ring topology: A network cabling configuration in which each system is connected in a series, forming a closed loop.

Router: A device that connects two networks at the Network layer (Layer 3) of the OSI model; operates like a bridge but also can choose routes through a network.

RMON: An SNMP standard for managing network devices; lets network engineers with properly configured SNMP management consoles view packet information on a port-by-port basis.



Server: A network node that provides services to client PCs, for example, file access, print spooling or remote execution.

SNMP (Simple Network Management Protocol): A de facto standard for managing network devices, including adapters, switches, routers, servers and workstations; garners information from various agents.

Star topology: A network cabling configuration that uses a central connection point (called a hub), through which all communication must pass.

Store-and-forward: A switching technique, used by bridges and switches, in which complete packets of information are stored in internal buffers before they are sent to another port.

STP: Shielded Twisted Pair; a thin-diameter network wire, wrapped with a metal sheath for extra protection against electrical interference.

Switching: The process by which packets are received, stored and transmitted to the appropriate destination port.

TCP/IP: Transmission Control Protocol/Internet Protocol; a network protocol that breaks messages into manageable chunks and verifies that they arrive at the correct destination node.

Thick Ethernet: The original Ethernet cable specification, requiring an AUI connector; noise-resistant, but expensive and difficult to install.

Thinnet: (Thin Ethernet) A CSMA/CD network based on thin coaxial cable (also called thin Ethernet) that requires a BNC connector; based on the 10BASE-2 IEEE standard.

Token passing: A network transmission method that requires a node to have control of a "token" before it can send messages; typically fairer than CSMA/CD on busy networks, but more complicated to implement.

Token Ring: IBM's implementation of token passing, governed by the IEEE 802.5 standard; second most popular network topology after Ethernet.

Twisted pair: A popular and low-cost LAN cabling method, also commonly used for telephone wiring; uses two wires twisted together to minimize electrical interference (see STP and UTP).

URL: Uniform Resource Locator, the standard way to write the address of a specific site or piece of information on the Web; for example,

UTP: Unshielded Twisted Pair; a thin-diameter network wire that is very popular in network cabling installations.



Virtual terminal: A terminal emulation program that makes a workstation appear to be a dumb terminal connected to some remote system, such as a mainframe.

VLANs: Virtual LANs; a switching technology that enables logical segmentation of switched networks, independent of physical grouping or collision domains.

Wide Area Network (WAN): A geographically dispersed network that connects two or more LANs; typically involves dedicated high-speed phone lines or satellites.

Workgroup (also called segment): A grouping of workstations, server(s) and any network devices dedicated to similar functions, using similar applications and/or sharing common resources, and serving as a subnetwork entity; members may have a common geography or function, e.g., engineering, marketing, manufacturing and administration.

Workstation: For the purposes of this guide, a personal computer in a network; also called a client.

X.25: A WAN standard for protocols and message formats; used to access public packet-switching networks.