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 is a telecommunication technology that offers data speeds up to 10 billion bits per second. It differs from traditional Ethernet in that it is a full-duplex protocol and does not require Carrier Sense Multiple Access/Collision Detection (CSMA/CD).

  • 10-high-day busy period (10HD busy period)

    In designing and assessing networks, the peak load is sometimes measured using the 10HD (10-high-day) busy period method.

  • 100 Gigabit Ethernet (100GbE)

    100 Gigabit Ethernet (100GbE) is a standard in development that will enable the transfer of Ethernet frames at 100 gigabits per second (gp/s). The 100GbE standard is for core switching. A 40GbE standard, in development simultaneously, is designed for server connectivity. Both standards are expected to be ratified in 2010.

  • 1000BASE-T

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

  • 100BASE-T

    In 100 Mbps (megabits per second) Ethernet (known as Fast Ethernet), there are three types of physical wiring that can carry signals: 100BASE-T4 (four pairs of telephone twisted pair wire) 100BASE-TX (two pairs of data grade twisted-pair wire) 100BASE-FX (a two-strand optical fiber cable) This designation is an Institute of Electrical and Electronics Engineers shorthand identifier.

  • 10BASE-2

    10BASE-2, one of several physical media specified by IEEE 802.3 for use in an Ethernet local area network (LAN), consists of Thinwire coaxial cable with a maximum segment length of 185 meters.

  • 10BASE-36

    10BASE-36 is a type of physical cabling defined in the IEEE 802.3 (Ethernet) standard for broadband application.

  • 10BASE-5

    10BASE-5, one of several physical media specified by IEEE 802.3 for use in an Ethernet local area network (LAN), consists of Thickwire coaxial cable with a maximum segment length of 500 meters.

  • 10BASE-F

    10BASE-F, one of several physical media specified by IEEE 802.3, is the use of optical fiber in an Ethernet local area network (LAN).

  • 10BASE-T

    10BASE-T, one of several physical media specified in the IEEE 802.3 standard for Ethernet local area networks (LANs), is ordinary telephone twisted pair wire.

  • 32-bit IP addressing

    32-bit IP addressing is the IP address scheme used in Internet Protocol 4 (IPv6 uses a 128-bit system)... (Continued)

  • 3G (third generation of mobile telephony)

    3G refers to the third generation of mobile telephony (that is, cellular) technology. The third generation, as the name suggests, follows two earlier generations. (Continued....)

  • 3GPP (3rd Generation Partnership Project)

    The 3GPP, also known as the 3rd Generation Partnership Project, 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, engineered to greatly increase the speed and responsiveness of wireless networks.

  • 6G

    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.

  • 6to4

    6to4 is a tunneling mechanism used to transfer IPv6 (Internet Protocol version 6) packets over an IPv4 infrastructure, typically the IPv4 Internet. The 6to4 mechanism was created to support coexistence of both versions during the transition to IPv6, which is expected to take years. (Continued)

  • 802.11a

    802.11a is one of several specifications in the 802.11 family applicable to wireless local area networks (wireless LANs or WLANs).

  • 802.11s

    802.11s is a proposed amendment to the 802.11 wireless networking standards that will provide a vendor-neutral way to build wireless mesh networks over wireless LAN (WLAN) products.

  • 802.3

    802.3 is a standard specification for Ethernet, a method of physical communication in a local area network (LAN), which is maintained by the Institute of Electrical and Electronics Engineers (IEEE).

  • streaming network telemetry

    Streaming network telemetry is a real-time data collection service in which network devices such as routers, switches and firewalls continuously push network health data and interface measurements to a centralized collector.

  • A

    A-Law

    A-Law is the standard codec (compression/decompression) algorithm for pulse code modulation (PCM) from the ITU-T (the Telecommunication Standardization Sector of the International Telecommunications Union).

  • AARP (AppleTalk Address Resolution Protocol)

    AARP (AppleTalk Address Resolution Protocol) is a way to map between the physical hardware addresses of computers, such as those known to an Ethernet or token ring local area network, and their temporarily assigned AppleTalk network addresses.

  • AAUI (Apple attachment unit interface)

    An AAUI (Apple attachment unit interface) is the 14- or 15-pin port or connection interface on earlier models of Macintosh computers that allowed it to be connected by a short interface cable (or "transceiver") to an Ethernet cable.

  • acceleration hardware

    Acceleration hardware is a general term that refers to devices that speed up data communications, storage and retrieval, encryption and decryption, mathematical operations, graphics, and Web page viewing. Acceleration hardware can consist of an individual integrated circuit (also called an IC or chip), a printed circuit card, or a self-contained system.

  • access point base station

    Access point base station is the original term for what is now known as a femtocell.

  • ACK

    In some digital communication protocols, ACK is the name of a signal that data has been received successfully (for example, with an acceptable number of errors).

  • acoustic coupler

    An acoustic coupler is a hardware device that enables a modem (a device that converts signals from analog to digital and from digital back to analog) to connect to a voice circuit.

  • ACTA (America's Carriers Telecommunications Association)

    ACTA (America's Carriers Telecommunications Association) is a lobbying organization for over 165 small long-distance telephone carrier companies.

  • active network

    An active network is a network in which the nodes are programmed to perform custom operations on the messages that pass through the node.

  • ACTS (Automatic Coin Telephone System)

    ACTS (Automatic Coin Telephone System) is a public coin-operated telephone service that completes a variety of phone calls, times the calls, and collects payment without the aid of an operator.

  • adaptive routing (dynamic routing)

    Adaptive routing, also called dynamic routing, is a process for determining the optimal path a data packet should follow through a network to arrive at a specific destination. Adaptive routing can be compared to a commuter taking a different route to work after learning that traffic on his usual route is backed up.

  • address

    An address can mean the unique location of either ( an Internet server, (2) a specific file (for example, a Web page), or (3) an e-mail user. It is also used to specify the location of data within computer storage.

  • Address Resolution Protocol (ARP)

    Address Resolution Protocol (ARP) is a procedure for mapping a dynamic Internet Protocol address (IP address) to a permanent physical machine address in a local area network (LAN).

  • ADSL (Asymmetric Digital Subscriber Line)

    Also see Fast Guide to DSL. ADSL (Asymmetric Digital Subscriber Line) is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses.

  • Advanced Intelligent Network (AIN)

    The Advanced Intelligent Network (AIN) is a telephone network architecture that separates service logic from switching equipment, allowing new services to be added without having to redesign switches to support new services.

  • aggregator

    Like its synonym concentrator, an aggregator is any device that serves multiple other devices or users either with its own capabilities or by forwarding transmissions in a more concentrated and economical way.

  • akamaize

    For a Web site, to akamaize (pronounced AHK-uh-myez) is to accelerate the delivery of Web files by placing copies on servers closer to the user than the server that delivers the main file for a Web page.

  • Aloha (Aloha method)

    Aloha, also called the Aloha method, refers toa simple communications scheme in which each source (transmitter) in a network sends data wheneverthere is a frame to send.

  • American Wire Gauge (AWG)

    American Wire Gauge (AWG) is a U.S. standard set of non-ferrous wire conductor sizes.

  • AMTOR (amateur teleprinting over radio)

    AMTOR (amateur teleprinting over radio) is a digital communications method used by radio amateurs, in which the frequency of errors is reduced by handshaking or character repetition.

  • anti-replay protocol

    The anti-replay protocol is part of the Internet Engineering Task Force (IETF) Internet Protocol Security (IPSec) standard.

  • anycast

    In Internet Protocol Version 6 (IPv6), anycast is communication between a single sender and the nearest of several receivers in a group. The term exists in contradistinction to multicast, communication between a single sender and multiple receivers, and unicast, communication between a single sender and a single receiver in a network.

  • APPC (Advanced Program-to-Program Communication or LU 6.2)

    APPC (Advanced Program-to-Program Communication, sometimes called LU 6.2) is a communication protocol and programming interface standard that operates in the presentation layer and the session layer of the Open Systems Interconnection (OSI) communications model.

  • Appleshare

    The AppleShare protocol is a communications protocol from Apple Computer that allows client applications in a computer to exchange files with and request services from server programs in a computer network.

  • AppleTalk

    AppleTalk is a set of local area network communication protocols originally created for Apple computers.

  • 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

    Sitting at Layer 7 -- the very top of the Open Systems Interconnection (OSI) communications model -- the application layer provides services for an application program to ensure that effective communication with another application program on a network is possible.

  • application-aware networking (app-ware networking)

    Application-aware networking is the capacity of an intelligent network to maintain current information about applications that connect to it and, as a result, optimize their functioning as well as that of other applications or systems that they control.

  • application-defined networking

    Application-defined networking (ADN) is a networking scenario in which applications have the ability to adapt network environments to meet their needs, rather than having resources allocated by the network.

  • ARCNET

    ARCNET is a widely-installed local area network (LAN) technology that uses a token-bus scheme for managing line sharing among the workstations and other devices connected on the LAN.

  • Arista Extensible Operating System (Arista EOS)

    Extensible Operating System (EOS) is a scalable network operating system (OS) that offers high availability, streamlines maintenance processes, and enhances network security.

  • ARPA (Advanced Research Projects Agency)

    An agency of the United States Department of Defense, ARPA (Advanced Research Projects Agency) underwrote development for the precursor of the Internet, known as ARPANET. Initially a modest network of four interconnected university computers, ARPANET's initial purpose was to enable mainly scientific users at the connected institutions to communicate and share resources.

  • ARPANET

    ARPANET was the network that became the basis for the Internet. Based on a concept first published in 1967, ARPANET was developed under the direction of the U.S. Advanced Research Projects Agency (ARPA). In 1969, the idea became a modest reality with the interconnection of four university computers.

  • asymmetric communications

    In telecommunications, the term asymmetric (also asymmetrical or non-symmetrical) refers to any system in which the data speed or quantity differs in one direction as compared with the other direction, averaged over time.

  • Asynchronous

    In general, asynchronous -- pronounced ay-SIHN-kro-nuhs, from Greek asyn-, meaning "not with," and chronos, meaning "time" -- is an adjective describing objects or events that are not coordinated in time.

  • Asynchronous Pulsed Radiated Incident Light

    Asynchronous Pulsed Radiated Incident Light is a multi-duplicitous communication protocol (MDCP) used to configure wireless local area networks (WLANs) on the fly.

  • ATM (asynchronous transfer mode)

    ATM (asynchronous transfer mode) is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology.

  • attenuation

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

  • attenuation-to-crosstalk ratio (ACR) or headroom

    Attenuation-to-crosstalk ratio (ACR), also called headroom, is the difference, expressed as a figure in decibels (dB), between the signal attenuation produced by a wire or cable transmission medium and the near-end crosstalk (NEXT).

  • ATU-R (ADSL Terminal Unit - Remote)

    An ATU-R (ADSL Terminal Unit - Remote), sometimes called an "ADSL modem," is a hardware unit that is installed in any computer that uses a telephone company connection with Asymmetric Digital Subscriber Line (ADSL) service.

  • audible ring

    In a telephone system, an audible ring is the tone that is returned from the called party's switching device and heard by the caller. This tone indicates to the caller that the desired party is being rung.

  • Audiobook: Intrusion Prevention Fundamentals

    Intrusion Prevention Fundamentals: An introduction to network attack mitigation with IPS

  • AUI (attachment unit interface)

    The AUI (attachment unit interface) is the 15-pin physical connector interface between a computer's network interface card (NIC) and an Ethernet cable.

  • autofax

    Autofax is the automatic (computer-initiated) sending of a facsimile (fax) message over a network in one of two ways: ( to a receiving computer or fax machine that is always ready to receive and store or immediately print such transmissions or (2), in some cases, as an e-mail note.

  • automatic repeat request (ARQ)

    Automatic repeat request (ARQ) is a protocol for error control in data transmission.

  • autonomous system (AS)

    On the Internet, an autonomous system (AS) is the unit of router policy, either a single network or a group of networks that is controlled by a common network administrator (or group of administrators) on behalf of a single administrative entity (such as a university, a business enterprise, or a business division).

  • autotrunking

    Autotrunking is a function that can be activated for one or more switch ports in a Cisco system of virtual local area networks (VLANs), making those ports capable of carrying traffic for any or all of the VLANs accessible by a particular switch....

  • average bouncing busy hour (ABBH)

    In designing and assessing telephone networks, one approach is to measure the average bouncing busy hour (ABBH) traffic in various network trunks or trunk groups of the network.

  • average revenue per user or average revenue per unit (ARPU)

    Average revenue per user or average revenue per unit (ARPU) is an expression of the income generated by a typical subscriber or device per unit time in a telecommunications network... (Continued)

  • network availability

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

  • B

    B-channel (bearer channel)

    In the Integrated Services Digital Network (ISDN), the B-channel is the channel that carries the main data.

  • B8ZS (bipolar 8-zero substitution, binary 8-zero substitution, clear channel, clear 64)

    B8ZS (bipolar 8-zero substitution, also called binary 8-zero substitution, clear channel, and clear 64) is an encoding method used on T1 circuits that inserts two successive ones of the same voltage - referred to as a bipolar violation - into a signal whenever eight consecutive zeros are transmitted.

  • backbone

    A backbone is a larger transmission line that carries data gathered from smaller lines that interconnect with it.

  • balun

    A balun is a device that joins a balanced line (one that has two conductors, with equal currents in opposite directions, such as a twisted pair cable) to an unbalanced line (one that has just one conductor and a ground, such as a coaxial cable).

  • band

    In telecommunication, a band - sometimes called a frequency band - is a specific range of frequencies in the radio frequency (RF) spectrum, which is divided among ranges from very low frequencies (vlf) to extremely high frequencies (ehf).

  • bandwidth

    Network bandwidth is the capacity of a wired or wireless network communications link to transmit the maximum amount of data from one point to another over a computer network or internet connection in a given amount of time -- usually, one second.

  • baseband

    Describes a telecommunication system in which information is carried in digital form on a single unmultiplexed signal channel on the transmission medium.

  • baseboard management controller (BMC)

    A baseboard management controller (BMC) is a specialized service processor that monitors the physical state of a computer, network server or other hardware device using sensors and communicating with the system administrator through an independent connection... (continued)

  • Basic Rate Interface (BRI)

    In the Integrated Services Digital Network (ISDN), there are two levels of service: the Basic Rate Interface (BRI), intended for the home and small enterprise, and the Primary Rate Interface (PRI), for larger users.

  • baud

    Baud was the prevalent measure for data transmission speed until replaced by a more accurate term, bps (bits per second).

  • beamforming

    Beamforming is a type of RF (radio frequency) management in which an access point uses multiple antennas to send out the same signal.

  • Bearer Independent Call Control (BICC)

    Bearer Independent Call Control (BICC) is a signaling protocol based on N-ISUP that is used to support narrowband ISDN service over a broadband backbone network without interfering with interfaces to the existing network and end-to-end services.

  • Bel

    In electronics and communications, the Bel expresses the logarithmic ratio between two levels of signal power, voltage, or current.

  • Bellcore (Bell Communications Research)

    Bellcore (Bell Communications Research) provides certain centralized research and standards coordination for the regional Bell operating companies (RBOC)s.

  • BGAN (Broadband Global Area Network)

    BGAN (Broadband Global Area Network) is a mobile communications system created to transmit broadband wireless voice and data communications almost anywhere on the earth's surface.

  • BGP (Border Gateway Protocol)

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

  • Big Switch Big Network Controller

    Big Network Controller is the SDN controller for the Open Software Defined Network (SDN), a product suite for network virtualization released in November of 2012 by Big Switch Networks.

  • Big Switch Networks

    Big Switch Networks is a network virtualization and SDN (software-defined networking) company that was founded in 2010.

  • Big Switch Networks Big Tap

    Big Tap is a network monitoring application that runs on Big Network Controller, the SDN controller for the Open Software-Defined Network (SDN).

  • Big Switch Networks Big Virtual Switch

    Big Virtual Switch is a data center network virtualization application that runs on Big Network Controller, the SDN controller for the Open Software-Defined Network (SDN).

  • big-endian and little-endian

    Endianness is a term that describes the order in which a sequence of bytes are stored in computer memory. Endianness can be either big or small, with the adjectives referring to which value is stored first.

  • bit rate

    In digital telecommunication, the bit rate is the number of bits that pass a given point in a telecommunication network in a given amount of time, usually a second.

  • bit robbing

    Bit robbing is a technique used in signaling on the T-carrier system, the widely-used system for transmitting both voice and data in digital form in the public switched telephone network (PSTN) and in private networks.

  • bit stream

    A bit stream is a contiguous sequence of bits, representing a stream of data, transmitted continously over a communications path, serially (one at a time).

  • bit stuffing

    Bit stuffing is the insertion of one or more bits into a transmission unit as a way to provide signaling information to a receiver... (Continued)

  • bits per second (bps or bit/sec)

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

  • BNC (Bayonet Neil-Concelman or British Naval Connector)

    A BNC (Bayonet Neil-Concelman, or sometimes British Naval Connector) connector is used to connect a computer to a coaxial cable in a 10BASE-2 Ethernet network. 10BASE-2 is a 10 MHz baseband network on a cable extending up to 185 meters - the 2 is a rounding up to 200 meters - without a repeater cable.

  • BOC (Bell operating company)

    BOC (Bell operating company) is a term for any of the 22 original companies (or their successors) that were created when AT&T was broken up in 1983 and given the right to provide local telephone service in a given geographic area.

  • bogon

    A bogon is an illegitimate IP 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 Internet Assigned Number Authority (IANA).

  • BOOTP (Bootstrap Protocol)

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

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