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 or using the search box below.

  • A

    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....

  • availability

    1) In a telephone circuit, availability is the ratio between the time during which the circuit is operational and elapsed time. 2) In a network switching system, availability is the accessibility of input and output ports.

  • 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)

  • 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

    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.