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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    10 Gigabit Ethernet (10 GbE)

    10 Gigabit Ethernet (10 GbE) is a telecommunication technology that offers data speeds up to 10 billion bits per second.

  • 100 Gigabit Ethernet (100 GbE)

    100 Gigabit Ethernet (100 GbE) is an Ethernet standard that supports data speeds of up to 100 billion bits (gigabits) per second (Gbps).

  • 1000BASE-T (Gigabit Ethernet)

    1000BASE-T is Gigabit Ethernet -- 1 gigabit is 1,000 megabits per second (Mbps) on copper cables, using four pairs of Category 5 (Cat5) unshielded twisted pair (UTP) to achieve the gigabit data rate.

  • 10BASE-T

    10BASE-T is an Ethernet standard for local area networks and one of several physical media specified in the Institute of Electrical and Electronics Engineers (IEEE) 802.3 standard.

  • 3G (third generation of mobile telephony)

    3G refers to the third generation of cellular technology that enables mobile telephony.

  • 3GPP (3rd Generation Partnership Project)

    The 3rd Generation Partnership Project (3GPP) is a collaborative project between a group of telecommunications associations with the initial goal of developing globally applicable specifications for third-generation (3G) mobile systems.

  • 5G

    Fifth-generation wireless (5G) is the latest iteration of cellular technology.

  • 5G standalone (5G SA)

    5G standalone (5G SA) is a cellular infrastructure built specifically for 5G services by implementing 5G standards and protocols in the radio network and controller core.

  • What is 6G? Overview of 6G networks & technology

    6G (sixth-generation wireless) is the successor to 5G cellular technology. 6G networks will be able to use higher frequencies than 5G networks and provide substantially higher capacity and much lower latency.

  • A

    access control list (ACL)

    An access control list (ACL) is a list of rules that specifies which users or systems are granted or denied access to a particular object or system resource.

  • ACK (acknowledgement)

    In some digital communication protocols, ACK -- short for 'acknowledgement' -- refers to a signal that a device sends to indicate that data has been received successfully.

  • Address Resolution Protocol (ARP)

    Address Resolution Protocol (ARP) is a protocol that maps dynamic IP addresses to permanent physical machine addresses in a local area network (LAN).

  • ADSL (Asymmetric Digital Subscriber Line)

    ADSL (Asymmetric Digital Subscriber Line) is a technology that facilitates fast data transmission at a high bandwidth on existing copper wire telephone lines to homes and businesses.

  • American Wire Gauge (AWG)

    American Wire Gauge (AWG) is the standard way to denote wire size in North America.

  • anti-replay protocol

    The anti-replay protocol provides Internet Protocol (IP) packet-level security by making it impossible for a hacker to intercept message packets and insert changed packets into the data stream between a source computer and a destination computer.

  • application delivery controller (ADC)

    An application delivery controller (ADC) is a network component that manages and optimizes how client machines connect to web and enterprise application servers.

  • application layer

    The application layer sits at Layer 7, the top of the Open Systems Interconnection (OSI) communications model. It ensures an application can effectively communicate with other applications on different computer systems and networks.

  • ARPANET

    The U.S. Advanced Research Projects Agency Network (ARPANET) was the first public packet-switched computer network.

  • asymmetric communications

    Asymmetric communications is a term pertaining to any system in which the data speed or quantity, when averaged over time, is different in one direction from the other.

  • attenuation

    Attenuation is a general term that refers to any reduction in the strength of a signal.

  • autonomous system (AS)

    An autonomous system (AS) in networking is a collection of one or more associated Internet Protocol (IP) prefixes with a clearly defined routing policy that governs how the AS exchanges routing information with other autonomous systems.

  • network availability

    Network availability is the amount of uptime in a network system over a specific time interval.

  • What is asynchronous?

    In general, asynchronous -- from Greek asyn- ('not with/together') and chronos ('time') -- describes objects or events not coordinated in time.

  • B

    bandwidth (network bandwidth)

    Network bandwidth is a measurement indicating the maximum capacity of a wired or wireless communications link to transmit data over a network connection in a given amount of time.

  • baseband

    Baseband in the transmission of communications signals means only one path is available to send and receive digital signals between devices.

  • baseboard management controller (BMC)

    A baseboard management controller (BMC) is a specialized service processor that remotely monitors the physical state of a host system, such as a computer, network server or other hardware devices.

  • beamforming

    Beamforming is a type of radio frequency (RF) management in which a wireless signal is directed toward a specific receiving device.

  • BGP (Border Gateway Protocol)

    BGP (Border Gateway Protocol) is the protocol that enables the global routing system of the internet.

  • big-endian and little-endian

    The term endianness describes the order in which computer memory stores a sequence of bytes.

  • bit stuffing

    Bit stuffing refers to the insertion of one or more bits into a data transmission as a way to provide signaling information to a receiver.

  • bits per second (bps or bit/sec)

    In data communications, bits per second (bps or bit/sec) is a common measure of data speed for computer modems and transmission carriers.

  • bogon

    A bogon is an illegitimate Internet Protocol address that falls into a set of IP addresses that have not been officially assigned to an entity by an internet registration institute, such as the IANA.

  • BOOTP (Bootstrap Protocol)

    BOOTP (Bootstrap Protocol) is an internet protocol that lets a network user automatically be configured to receive an IP address and have an operating system booted without user involvement.

  • bottleneck

    A bottleneck, in a communications context, is a point in the enterprise where the flow of data is impaired or stopped entirely.

  • broadband

    Broadband refers to telecommunications in which a wide band of frequencies is available to transmit information.

  • bus network

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

  • C

    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.

  • CAPWAP (Control and Provisioning of Wireless Access Points)

    CAPWAP (Control and Provisioning of Wireless Access Points) is a protocol that enables an access controller to manage a collection of wireless termination points.

  • carrier cloud

    A carrier cloud is a cloud computing environment that is owned and operated by a traditional telecommunications service provider.

  • carrier-to-noise ratio

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

  • CBRS (Citizens Broadband Radio Service)

    Citizens Broadband Radio Service, or CBRS, is the set of operational rules given to a slice of the shared wireless spectrum and the technologies used in that spectrum.

  • CCNA certification

    Cisco Certified Network Associate (CCNA) is a technical certification that Cisco offers for early-career networking professionals.

  • 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.

  • 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.

  • chatty protocol

    A chatty protocol is an application or routing protocol requiring a client or server to wait for an acknowledgment before transmitting data again.

  • CIDR (Classless Inter-Domain Routing or supernetting)

    CIDR (Classless Inter-Domain Routing or supernetting) is a method of assigning 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 switching

    Circuit switching is a type of network configuration in which a physical path is obtained and dedicated to a single connection between two endpoints in the network for the duration of a dedicated connection.

  • 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 IOS (Cisco Internetwork Operating System)

    Cisco IOS (Internetwork Operating System) is a collection of proprietary operating systems (OSes) that runs on Cisco hardware devices, including Cisco Systems network devices, routers and network switches.

  • Class of Service (CoS)

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

  • client-server

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

  • Clos network

    A Clos network is a type of nonblocking, multistage switching network used today in large-scale data center switching fabrics.

  • cloud radio access network (C-RAN)

    Cloud radio access network (C-RAN) is a centralized, cloud computing-based architecture for radio access networks.

  • coaxial cable

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

  • coded orthogonal frequency-division multiplexing (COFDM)

    Coded orthogonal frequency-division multiplexing (COFDM) is a telecommunications 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 ones are not.

  • collision in networking

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

  • committed information rate (CIR)

    Committed information rate (CIR) is the guaranteed rate at which a Frame Relay network will transfer information under normal line conditions.

  • 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 is a group of interconnected nodes or computing devices that exchange data and resources with each other.

  • conductance

    Conductance is an expression of the ease with which electric current flows through materials like metals and nonmetals.

  • 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.

  • connectionless

    In telecommunications, connectionless describes communication between two network endpoints in which a message can be sent from one endpoint to another without prior arrangement.

  • control plane (CP)

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

  • CPRI (Common Public Radio Interface)

    CPRI (Common Public Radio Interface) is a specification for wireless communication networks that defines the key criteria for interfacing transport, connectivity and control communications between baseband units (BBUs) and remote radio units (RRUs), which are also called remote radio heads (RRHs).

  • 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 E1 trunk lines.

  • 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 a modem. It converts a digital data frame from local area network (LAN) communication technology into a frame appropriate for a wide area network (WAN) and vice versa.

  • customer premises equipment (CPE)

    Customer premises equipment (CPE) is telecommunications and information technology equipment kept at the customer's physical location rather than on the service provider's premises.

  • customer proprietary network information (CPNI)

    Customer proprietary network information (CPNI) in the United States is information that telecommunications services -- such as local, long-distance and wireless telephone companies -- acquire about their subscribers.

  • What is a cloud-native network function (CNF)?

    A cloud-native network function (CNF) is a service that performs network duties in software, as opposed to purpose-built hardware.

  • What is Cisco Performance Routing (PfR)?

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

  • What is cloud networking?

    Cloud networking is a type of IT infrastructure in which the cloud hosts some or all of an organization's networking resources.

  • D

    data center interconnect (DCI)

    Data center interconnect (DCI) technology links two or more data centers together to share resources.

  • data link layer

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

  • data plane

    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 from one or more sources at a steady, high speed for processing into specific outputs.

  • deep packet inspection (DPI)

    Deep packet inspection (DPI) is an advanced method of examining and managing network traffic.

  • delay-tolerant network (DTN)

    A delay-tolerant network (DTN) is a network that's designed to operate effectively in extreme conditions and over very large distances, such as with space communications.

  • dense wavelength-division multiplexing (DWDM)

    Dense wavelength-division multiplexing (DWDM) is an optical fiber multiplexing technology that is used to increase the bandwidth of existing fiber networks.

  • DHCP (Dynamic Host Configuration Protocol)

    DHCP (Dynamic Host Configuration Protocol) is a network management protocol used to dynamically assign an IP address to any device, or node, on a network so it can communicate using IP.

  • domain name system (DNS)

    The domain name system (DNS) is a naming database in which internet domain names are located and translated into Internet Protocol (IP) addresses.

  • downloading

    Downloading is the transmission of a file or data from one computer to another over a network, usually from a larger server to a user device.

  • DTMF (dual tone multi-frequency)

    Dual tone multi-frequency (DTMF) is the sounds or tones generated by a telephone when the numbers are pressed.

  • dynamic and static

    In general, dynamic means 'energetic, capable of action and/or change, or forceful,' while static means 'stationary or fixed.'

  • dynamic multipoint VPN (DMVPN)

    A dynamic multipoint virtual private network (DMVPN) is a secure network that exchanges data between sites/routers without passing traffic through an organization's virtual private network (VPN) server or router located at its headquarters.

  • dynamic port numbers

    Dynamic port numbers, also known as private port numbers, are the port numbers that are available for use by any application to use in communicating with any other application, using the internet's Transmission Control Protocol (TCP) or User Datagram Protocol (UDP).

  • E

    east-west traffic

    East-west traffic, in a networking context, is the transfer of data packets from server to server within a data center.

  • edge device

    An edge device is any piece of hardware that controls data flow at the boundary between two networks.

  • encapsulation (object-orientated programming)

    In object-oriented programming (OOP), encapsulation is the practice of bundling related data into a structured unit, along with the methods used to work with that data.

  • encoding and decoding

    Encoding and decoding are used in many forms of communications, including computing, data communications, programming, digital electronics and human communications.

  • Enhanced Interior Gateway Routing Protocol (EIGRP)

    Enhanced Interior Gateway Routing Protocol (EIGRP) is a network protocol that enables routers to exchange information more efficiently than earlier network protocols, such as Interior Gateway Routing Protocol (IGRP) or Border Gateway Protocol (BGP).

  • Ethernet

    Ethernet is the traditional technology for connecting devices in a wired local area network (LAN) or wide area network.

  • Evolved Packet Core (EPC)

    Evolved Packet Core (EPC) is a framework for providing converged voice and data services on a 4G Long-Term Evolution (LTE) network.

  • extranet

    An extranet is a private network that enterprises use to provide trusted third parties -- such as suppliers, vendors, partners, customers and other businesses -- secure, controlled access to business information or operations.