Networking Definitions

This glossary explains the meaning of key words and phrases that information technology (IT) and business professionals use when discussing networking and related software products. You can find additional definitions by visiting WhatIs.com or using the search box below.

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  • B

    Broadband over Power Line (BPL)

    Broadband over Power Line (BPL) is a technology that allows Internet data to be transmitted over utility power lines.

  • broadband voice gateway

    A broadband voice gateway is a device that allows you to make telephone calls over a high-speed Internet connection rather than through a regular telephone outlet without having to go through your computer.

  • brouter

    A brouter (pronounced BRAU-tuhr or sometimes BEE-rau-tuhr) is a network bridge and a router combined in a single product.

  • burst

    Burst is a term used in a number of information technology contexts to mean a specific amount of data sent or received in one intermittent operation.

  • bus network

    A bus network is an arrangement in a local area network (LAN) in which each node (workstation or other device) is connected to a main cable or link called the bus.

  • BYE packet

    A BYE (or Goodbye) packet is a type of Real-Time Transport Control Protocol (RTCP) packet that is sent when a participant in a multicast event leaves the session.

  • C

    cable head-end

    A cable head-end (or headend) is the facility at a local cable TV office that originates and communicates cable TV services and cable modem services to subscribers.

  • cable modem termination system (CMTS)

    A cable modem termination system (CMTS) is a component that exchanges digital signals with cable modems on a cable network.

  • cable TV or CATV (community antenna television)

    Cable TV is also known as "CATV" (community antenna television).

  • call failure rate (CFR)

    The call failure rate (CFR) is the percentage of calls to an ISP or any network provider that fail to get through. The CFR is commonly used as a statistical measure in assessing Internet service providers.

  • caller ID spoofing

    Caller ID spoofing is a service that allows a caller to masquerade as someone else by falsifying the number that appears on the recipient's caller ID display... (Continued)

  • campus network

    A campus network is a proprietary local area network (LAN) or set of interconnected LANs serving a corporation, government agency, university, or similar organization.

  • capacity planning

    In information technology, capacity planning is the science and art of estimating the space, computer hardware, software and connection infrastructure resources that will be needed over some future period of time.

  • CAPWAP (Control and Provisioning of Wireless Access Points)

    CAPWAP (Control and Provisioning of Wireless Access Points) is a standardized protocol that enables wireless LAN (WLAN) controllers to centrally manage a group of wireless access points (APs).

  • care-of address

    In Internet routing, a care-of address is a temporary IP address for a mobile node (mobile device) that enables message delivery when the device is connecting from somewhere other than its home network.

  • carrier cloud

    A carrier cloud is a cloud computing system, or network of servers that store data in a way that it is easily accessible from multiple locations, that is owned and operated by a traditional telecommunications service provider.

  • carrier detect

    Carrier detect (see modem lights) is a control signal between a modem and a computer that indicates that the modem detects a "live" carrier that can be used for sending and receiving information.

  • Carrier Ethernet

    Carrier Ethernet is the use of high-bandwidth Ethernet technology for Internet access and for communication among business, academic and government local area networks (LANs)... (Continued)

  • Carrier Sense Multiple Access/Collision Detect (CSMA/CD)

    Carrier Sense Multiple Access/Collision Detect (CSMA/CD) is the protocol for carrier transmission access in Ethernet networks.

  • carrier signal

    A carrier signal is a transmitted electromagnetic pulse or wave at a steady base frequency of alternation on which information can be imposed by increasing signal strength, varying the base frequency, varying the wave phase, or other means... (Continued)

  • carrier-to-noise ratio (CNR or C/N)

    In communications, the carrier-to-noise ratio, often written CNR or C/N, is a measure of the received carrier strength relative to the strength of the received noise.

  • CATV (community access television)

    CATV (originally "community antenna television," now often "community access television") is more commonly known as "cable TV." In addition to bringing television programs to those millions of people throughout the world who are connected to a community antenna, cable TV is an increasingly popular way to interact with the World Wide Web and other new forms of multimedia information and entertainment services.

  • CCITT or ITU-T (Telecommunication Standardization Sector of the International Telecommunications)

    The CCITT, now known as the ITU-T (for Telecommunication Standardization Sector of the International Telecommunications Union), is the primary international body for fostering cooperative standards for telecommunications equipment and systems.

  • CCNA certification

    Cisco Certified Network Associaten (CCNA) is an entry-level certification for the Cisco certified professional program.

  • CDDI (Copper Distributed Data Interface)

    For a local area network (LAN), CDDI (Copper Distributed Data Interface) is a standard for data transmission based on FDDI (Fiber Distributed Data Interface) that uses shielded twisted-pair (STP) or unshielded twisted pair (UTP) copper wire instead of fiber optic lines.

  • CDMA (Code-Division Multiple Access)

    CDMA (Code-Division Multiple Access) refers to any of several protocols used in second-generation (2G) and third-generation (3G) wireless communications.

  • CDN (content delivery network)

    A CDN (content delivery network), also called a content distribution network, is a group of geographically distributed and interconnected servers that provide cached internet content from a network location closest to a user to accelerate its delivery.

  • CDPD (Cellular Digital Packet Data)

    CDPD (Cellular Digital Packet Data) is a specification for supporting wireless access to the Internet and other public packet-switched networks.

  • CDSL (Consumer Digital Subscriber Line)

    Also see our Fast guide to DSL. CDSL (Consumer Digital Subscriber Line) is a version of Digital Subscriber Line (DSL) service, trademarked by Rockwell Corp.

  • central office (CO)

    In telephone communication in the United States, a central office (CO) is an office in a locality to which subscriber home and business lines are connected on what is called a local loop.

  • CenturyLink

    CenturyLink is an integrated telecommunications company that provides a wide variety of products and services to clients across the globe, including networking, cloud service and security solutions.

  • Certified Wireless Networking Professional (CWNP)

    Certified Wireless Networking Professional (CWNP)is the name for the family of wireless certifications from Planet3Wireless.

  • channel-associated signaling (CAS)

    Channel-associated signaling (CAS) is signaling (for example, in a T-carrier system line) in which control signals, such as those for synchronizing and bounding frames, are carried in the same channels as voice and data signals... (Continued)

  • chatty protocol

    A chatty protocol is an application or routing protocol that requires a client or server to wait for an acknowledgement before it can transmit again.

  • CIDR (Classless Inter-Domain Routing or supernetting)

    CIDR (Classless Inter-Domain Routing) -- also known as supernetting -- is a method of assigning Internet Protocol (IP) addresses that improves the efficiency of address distribution and replaces the previous system based on class A, class B and class C networks.

  • circuit-switched

    Circuit-switched is a type of network in which a physical path is obtained for and dedicated to a single connection between two end-points in the network for the duration of the connection.

  • circular mil

    The circular mil is a unit of area used especially when denoting the cross-sectional size of a wire or cable.

  • Cisco Certified Entry Networking Technician (CCENT)

    Cisco Certified Entry Networking Technician (CCENT) is a now-retired certification offered by Cisco, as part of their certification program.

  • Cisco Certified Internetwork Expert (CCIE certification)

    Cisco Certified Internetwork Expert (CCIE certification) is a series of technical certifications for senior networking professionals who design, build, implement, maintain and troubleshoot complex enterprise networking infrastructures.

  • Cisco Certified Network Professional (CCNP)

    Cisco Certified Network Professional (CCNP) is an intermediate-level certification in the Cisco certified professional program.

  • Cisco Enterprise Agreement (EA)

    Cisco Enterprise Agreement (EA) is a software buying program that digitizes and simplifies license management for Cisco suite customers.

  • Cisco Information Security Specialist (CISS)

    Cisco Information Security Specialist (CISS) is an entry-level certification attesting that the holder has demonstrated the foundational knowledge and skills required to install and support a Cisco Self-Defending Network... (Continued)

  • Cisco Integrated Service Routers Generation 2 (ISR G2)

    ISR G2 is a second generation Integrated Services Router (ISR) from Cisco Systems, Inc.

  • Cisco IOS (Cisco Internetwork Operating System)

    Cisco IOS (Internetwork Operating System) is a proprietary operating system that runs on Cisco Systems routers and switches.

  • Cisco LISP (Location Identifier Separation Protocol)

    LISP (Location Identifier Separation Protocol) is a routing and addressing architecture developed by Cisco Systems. LISP creates two addresses for each network node: one for its identity and another for its location in the network.

  • Cisco Performance Routing (PfR)

    Cisco Performance Routing (PfR) is a way of sending network packets based on intelligent path control.

  • Class of Service (CoS)

    Class of Service (CoS) is a way of managing traffic in a network by grouping similar types of traffic (for example, e-mail, streaming video, voice, large document file transfer) together and treating each type as a class with its own level of service priority.

  • client-server model (client-server architecture)

    Client-server is a relationship in which one program (the client) requests a service or resource from another program (the server).

  • clone

    A clone is an identical copy of something and is a term that first became familiar to the public from the biosciences.

  • Clos network

    A Clos network is a type of non-blocking, multistage switching architecture that reduces the number of ports required in an interconnected fabric.

  • cloud

    In telecommunications, a cloud is the unpredictable part of any network through which data passes between two end points.

  • cloud federation

    Cloud federation is the practice of interconnecting service providers' cloud environments to load balance traffic and accommodate spikes in demand.

  • cloud networking

    Cloud networking is when some or all of an organization's networking resources are hosted in the cloud.

  • cloud radio access network (C-RAN)

    C-RAN, or cloud radio access network, is a centralized, cloud computing-based architecture for radio access networks (RAN) that enables large-scale deployment, collaborative radio technology support and real time virtualization capabilities.

  • coarse wavelength division multiplexing (CWDM)

    Coarse wavelength division multiplexing (CWDM) is a method of combining multiple signals on laser beams at various wavelengths for transmission along fiber optic cables, such that the number of channels is fewer than in dense wavelength division multiplexing (DWDM) but more than in standard wavelength division multiplexing (WDM).

  • coaxial cable

    Coaxial cable is a type of copper cable specially built with a metal shield and other components engineered to block signal interference.

  • COFDM

    COFDM is a modulation scheme that divides a single digital signal across 1,000 or more signal carriers simultaneously.

  • cognitive radio (CR)

    Cognitive radio (CR) is a form of wireless communication in which a transceiver can intelligently detect which communication channels are in use and which are not, and instantly move into vacant channels while avoiding occupied ones... (Continued)

  • collision

    In a half duplex Ethernet network, a collision is the result of two devices on the same network attempting to transmit data at exactly the same time.

  • comfort noise generator (CNG)

    A comfort noise generator (CNG) is a program used to generate background noise artificially for voice communications during periods of silence that occur during the course of conversation... (Continued)

  • committed information rate (CIR)

    committed information rate

  • common channel signaling (CCS)

    Common channel signaling (CCS) is signaling (for example, in a T-carrier system line) in which a group of voice-and-data channels share a separate channel that is used only for control signals.

  • Common Management Information Protocol (CMIP)

    Common Management Information Protocol (CMIP) is a network management protocol built on the Open Systems Interconnection (OSI) communication model.

  • computer hardware

    Computer hardware is a collective term used to describe any of the physical components of an analog or digital computer.

  • computer network

    A computer network, also referred to as a data network, is a series of interconnected nodes that can transmit, receive and exchange data, voice and video traffic.

  • concentrator

    As generally used, a concentrator is a device that acts as an efficient forwarder of data transmission signals.

  • conductance

    Conductance is an expression of the ease with which electric current flows through a substance.

  • connection

    In telecommunication and computing in general, a connection is the successful completion of necessary arrangements so that two or more parties (for example, people or programs) can communicate at a long distance.

  • connection-oriented

    In telecommunications, connection-oriented describes a means of transmitting data in which the devices at the end points use a preliminary protocol to establish an end-to-end connection before any data is sent.

  • connectionless

    In telecommunication, connectionless describes communication between two network end points in which a message can be sent from one end point to another without prior arrangement.

  • Constellation

    Constellation was the early name for the Communicator browser and related programs from Netscape Communications.

  • context-aware network access control

    Context-aware network access control (CANAC) is an approach to managing the security of a proprietary network by granting access to network resources according to contextual-based security policies.

  • control plane (CP)

    The control plane is the part of a network that carries signaling traffic and is responsible for routing.

  • COPS (Common Open Policy Service Protocol)

    COPS (Common Open Policy Service Protocol) is a proposed standard protocol for exchanging network policy information between a policy decision point (PDP) in a network and policy enforcement points (PEPs) as part of overall Quality of Service (QoS) - the allocation of network traffic resources according to desired priorities of service.

  • core router

    A core router is a router that forwards packets to computer hosts within a network (but not between networks).

  • corporate area network (CAN)

    A corporate area network (CAN) is a separate, protected portion of a corporation's intranet.

  • CPNI (Customer Proprietary Network Information)

    In the United States, CPNI (Customer Proprietary Network Information) is information that telecommunications services such as local, long distance, and wireless telephone companies acquire about their subscribers.

  • CPRI (Common Public Radio Interface)

    CPRI (Common Public Radio Interface) is a specification for wireless communication networks in the interface between radio equipment and radio equipment control.

  • CRC-4 (Cyclic Redundancy Check 4)

    CRC-4 (Cyclic Redundancy Check 4) is a form of cyclic redundancy checking (a method of checking for errors in transmitted data) that is used on E-1 trunk lines.

  • cross-bar switch

    In a network, a cross-bar switch is a device that is capable of channeling data between any two devices that are attached to it up to its maximum number of ports.

  • crossover cable

    A crossover cable is a cable that is used to interconnect two computers by "crossing over" (reversing) their respective pin contacts.

  • crosstalk

    Crosstalk is a disturbance caused by the electric or magnetic fields of one telecommunication signal affecting a signal in an adjacent circuit.

  • CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)

    CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) is a protocol for carrier transmission in 802.11 networks.

  • CSU/DSU (Channel Service Unit/Data Service Unit)

    A CSU/DSU (Channel Service Unit/Data Service Unit) is a hardware device about the size of an external modem that converts a digital data frame from the communications technology used on a local area network (LAN) into a frame appropriate to a wide-area network (WAN) and vice versa.

  • CTI (computer-telephony integration)

    CTI (computer-telephony integration), or sometimes simply "computer telephony," is the use of computers to manage telephone calls.

  • customer premises equipment (CPE)

    Customer premises equipment (CPE) is telephone or other service provider equipment that is located on the customer's premises (physical location) rather than on the provider's premises or in between.

  • cycles per second (CPS)

    Cps (cycles per second) is the measure of how frequently an alternating current changes direction.

  • cyclic redundancy checking

    Cyclic redundancy checking is a method of checking for errors in data that has been transmitted on a communications link.

  • D

    D-channel

    In the Integrated Services Digital Network (ISDN), the D-channel is the channel that carries control and signalling information.

  • daisy chain

    A daisy chain is an interconnection of computer devices, peripherals, or network nodes in series, one after another. It is the computer equivalent of a series electrical circuit.

  • dark fiber

    Dark fiber is optical fiber infrastructure (cabling and repeaters) that is currently in place but is not being used.

  • darknet

    A darknet is a routed allocation of IP address space that is not discoverable by any usual means.

  • DARPA (Defense Advanced Research Projects Agency)

    DARPA (Defense Advanced Research Projects Agency) is the independent research branch of the U.S. Department of Defense that funded a project that in time was to lead to the creation of the Internet.

  • DARPANET

    DARPANET (or DARPANet) is a term sometimes used for the ARPANET, the early network from which today's Internet evolved.

  • data center interconnect (DCI)

    Data center interconnect (DCI) is a segment of the networking market that focuses on the technology used to link two or more data centers so the facilities can share resources. There are many options for DCI connectivity and selecting the right one depends upon a wide range of variables, including the location of the data centers, the distance between data centers, bandwidth and availability requirements, the capabilities of local service providers and security concerns.

  • data link control (DLC)

    DLC also is an abbreviation for digital loop carrier.

  • data plane (DP)

    The data plane (sometimes known as the user plane, forwarding plane, carrier plane or bearer plane) is the part of a network that carries user traffic.

  • data streaming

    Data streaming is the continuous transfer of data at a steady, high-speed rate. To facilitate the need for real-time analytics from disparate data sources, many companies have replaced traditional batch processing with streaming data architectures that can accommodate batch processing.

  • Data-Link layer

    The data link layer is the protocol layer in a program that handles the moving of data into and out of a physical link in a network.

  • datagram

    A datagram is, to quote the Internet's Request for Comments 1594, "a self-contained, independent entity of data carrying sufficient information to be routed from the source to the destination computer without reliance on earlier exchanges between this source and destination computer and the transporting network."

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