Glossary 0-A

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  • 10Base2: The IEEE specification for thin Ethernet coaxial cable, also known as thinnet or cheapernet.
  • 10Base5: An implementation of the Ethernet IEEE standard on twinaxial cable, a baseband medium, at 10 megabits per second. The maximum segment length is 500 meters.
  • 10BaseF: The IEEE 802.3 standard for Ethernet running over fiber. It includes subgroups 10BaseFB (synchronous fiber serial chains repeaters) 10BaseFL (asynchronous fiber, inter operable with FOIRL, greater link distances) 10BaseFP (asynchronous fiber & passive star topology)
  • 10BaseT: An IEEE 802.3 specification for Ethernet over unshielded twisted pair cabling. Differs from the original Ethernet standard in allowing a star topology rather than a linear bus. Devices can be located up to 100 meters from the concentrator/hub.
  • 1Base5: An implementation of the StarLAN IEEE standard on a baseband medium at 1 megabit per second. The maximum segment length is 500 meters.
  • A: See Ampere
  • Abrasion Resistance: The Ability to Resist Surface wear.
  • AC: See Alternating Current or Access Control
  • Accelerated Aging: A test that simulates long time environmental conditions in a relatively short time.
  • Acceptable Use Policy: (AUP) This refers to policies that restrict the way in which a network may be used. Usually, a network administrator makes & enforces decisions dealing with acceptable use.
  • Access Control: (AC) Contains a token indicator & frame priority on token ring networks.
  • Access Method: A set of rules which the networks arbitrate their use.
  • ACK: Short for Acknowledgment. ACK is a data link control character sent upon receipt of an error-free message. It is used to indicate that a message was received correctly.
  • ACR: See Attenuation Crosstalk Radio
  • ACSE: See Association Control Service Element
  • Active/Passive device: Active either amplifies the signal or retransmits the signal, usually requiring external power. Passive lets the signal go through, sometimes weakening it. Passive devices don't require any power.
  • ACU: See Automatic Calling Unit
  • Adapter: A device that makes two non-matching pieces work together; Power adapter for equipment that can't use the supply voltage. Connector Adapters (SCSI, Phone, etc.) to match the port with the connector on the cable.
  • Adapter Card: A printed circuit board which is installed in a PC. It provides the communications interface to the network. Also referred to as a NIM (Network Interface Module). See also NIC (Network Interface Card).
  • ADC: See Advanced Data Communications
  • Address: A unique number identifying a node on a network. There are only two types of Addresses; Hardware = OSI Layer 2 & Internet = OSI layer 3.
  • Address Mask: The address mask is used to identify the parts of an IP address that correspond to the different sections (separated by dots). It's also known as the "subnet mask" since the network portion of an address can be determined by the encoding inherent in an IP address.
  • Address Resolution: The process of determining what LAN hardware address (level 2) corresponds to an Internet Protocol address (level 3). Used by routers & hosts before transmitting a packet on a LAN.
  • Address Resolution Protocol: (ARP) The data link layer protocol used by the IP layer of routers & hosts in a TCP/IP network. It is used to determine a local hardware address of a node on a directly attached LAN, given its IP address responds with its hardware address.
  • Address Table: The list of host addresses & link numbers maintained by a bridge to determine where to forward packets.
  • Adjusted Ring Length: (ARL) In a multiple-wiring closet ring, the adjusted ring length is the sum of all wiring closet-to-closet cables in the main ring path less the length of the shortest of these cables, times two.
  • Advanced Data Communications: (ADC) The USA Federal Standard Communications Protocol.
  • Advanced Program-to-Program Communications: (APPC) Primarily for personal computers in an SNA network to communicate with a mainframe host, this implementation of LU 6.2 uses high-level program interaction.
  • Advanced Research Projects Agency: (ARPA) The Group Developed within the US Department of Defense for research purposes.
  • Aerial Cable: Telecommunication cable installed on aerial supporting structures.
  • AF: See Audio Frequency
  • AFP: See AppleTalk Filing Protocol
  • Agent: Part of a system's software that performs information retrieval & exchange on behalf of a client or server application.
  • Air Core Cable: A cable in which the interstices in the cable core are not filled with a moisture barrier.
  • Alias: A type of nickname (usually short & easy to remember) that refers to a type of network resource. Aliases are used so you won't have to remember the long & difficult names typical of network resources.
  • Alpeth: Aluminum-polyethylene, the primary sheath for aerial cable.
  • Alphanumeric: Describing a character set that contains letters, numbers & other characters such as punctuation marks.
  • Alternate Routing: A method of completing connections that uses another path when the primary circuit is unavailable, out of service, or busy.
  • Alternating Current: (AC) An electric current that periodically reverses direction of electron flow. The rate at which a full cycle occurs in a given unit of time (generally a second) is called the frequency of the current.
  • Alvyn: Aluminum-polyvinyl-chloride, the preferred sheath for riser cable where a flame-retardant sheath is required to meet NEC standards.
  • AM: See Amplitude Modulation
  • Ambient Noise: The existing noise in a transmission media. In telephone lines, this is usually heard as the background "hiss" & is due to electrical signals traveling down the line. Also called "background" or "white" noise.
  • American National Standards Institute: (ANSI) A voluntary U.S. based organization which defines standards for the information processing industry.
  • American Society for Testing Materials: (ASTM) An organization that tests materials & attempts to set standards on various materials for the industry.
  • American Standard Code for Information Interchange: (ASCII) A seven-bit-plus-parity code established by ANSI to achieve compatibility between data devices.
  • American Wire Gauge: (AWG) A wire diameter specification. The smaller the AWG number,. the larger the wire diameter
  • Ampere: (A) A standard unit of current. Defined as the amount of current that flows when one volt of EMF is applied across one ohm of resistance. An ampere of current is produced by one coulomb of charge passing a point in one second.
  • Amplifier: Any electronic component that boosts the strength or amplitude of a transmitted (usually analog) signal; functionally equivalent to a repeater in digital transmission.
  • Amplitude: The strength or magnitude of an analog signal. On a waveform, amplitude is measured as the distance between the peak & valley.
  • Amplitude Modulation: (AM) One of three basic ways to add information to a sine wave signal; the magnitude of the sine wave, or carrier, is modified in accordance with the information to be transmitted.
  • Analog: Representation of data by variable quantities.
  • Analog Recording: Transfer method that converts data from digital to analog format.
  • Anneal: To soften & relieve strains in any solid material, such as metal or glass, by heating to just below its melting point & then slowly cooling it. Annealing generally lowers the tensile strength of the material, while improving its flex life & flexibility.
  • Anonymous FTP: By using the word "anonymous" as your user ID & your e-mail address as the password when you login to an FTP site, you can bypass local security checks & gain limited access to public files on the remote computer. This type of access is available on most FTP sites, but not all.
  • ANSI: See American National Standards Institute
  • API: See Application Program Interface
  • APPC: See Advanced Program-to-Program Communications
  • AppleShare: Apple Computer's network system implementing the AppleTalk protocols.
  • AppleTalk: Protocol suite defined by Apple Computer for connecting computers & peripherals using shielded twisted-pair wiring & transfer rates of about 230.4 kilobytes per second. The network- & transport-level protocols include Datagram Delivery Protocol (DDP) AppleTalk Transaction Protocol (ATP) AppleTalk Session Protocol (ASP) & the Name Binding Protocol (NBP)
  • AppleTalk Filing Protocol: (AFP) In an AppleTalk network, this link access-layer (or data link-layer) protocol governs packet transmission on LocalTalk.
  • Application: Sometimes known as a client or an "app," it's a program that performs a specific function. FTP, Mail, Gopher, Mosaic, & Telnet clients are the most common examples of Internet applications.
  • Application layer: A term used in reference to Layer 7 of the OSI model. This layer provides the means to access application services such as file-transfer, virtual-terminal functions, & electronic-mail functions.
  • Application Program: A program designed for a specific user
  • Application Program Interface: (API) A set of formalized software calls & routines that can be referenced by an application program to access underlying network services.
  • Application Specific Integrated Circuit: (ASIC) Custom made Integrated Circuits for specific applications, some of our switchboxes are compact and use less power because they're built with an ASIC.
  • Archie: You'll usually hear this term referred to in the phrase "archie search" Archie is a way of automatically gathering, indexing & sometimes even retrieving files on the Internet. Most good archie clients are able to FTP files once you've found the information you're looking for.
  • Archive: A collection of files stored on an Internet machine. FTP sites are known as archives.
  • ARCnet: A 2.5 megabit per second baseband, token-passing network designed by Datapoint Corporation that supports up to 255 nodes.
  • ARL: See Adjusted Ring Length
  • Armored Cable: A cable provided with a wrapping of metal for mechanical protection.
  • ARP: See Address Resolution Protocol
  • ARPA: See Advanced Research Projects Agency
  • ARPANET: The first major packet-switched network.
  • ARQ: See Automatic Request for Retransmission
  • ASCII: See American Standard Code for Information Interchange
  • ASIC: See Application Specific Integrated Circuit
  • Association Control Service Element: (ACSE) An application-level protocol.
  • ASTM: See American Society for Testing Materials An organization that tests materials & attempts to set standards on various materials for the industry.
  • Asynchronous Transfer Mode: (ATM) A high speed packet switching technology used to transmit video, data, voice, etc. via fixed-length cells of 53bytes.
  • Asynchronous Transmission: Data transmission technique controlled by stop & start bits. Sending & receiving DTE’s are not synchronized throughout the transmission.
  • ATM: See Asynchronous Transfer Mode
  • ATP: AppleTalk Transaction Protocol
  • Attachment Unit Interface: (AUI) Used with thick Ethernet often including drop cable & has a limit of 50 meters in length. The drop cable is DB15 Male to Female.
  • Attenuation: The power loss in an electrical system, or in other words, loss of signal strength. Its measurement is decibel/distance (typically dB/1,000 feet of dB/ft).
  • Attenuation Crosstalk Radio: (ACR) The difference between attenuation & crosstalk, measured in dB, at a given frequency
  • Audio: A term used to describe sounds within the range of human hearing. Also used to describe devices which are designed to operate within this range.
  • Audio Frequency: (AF) The range of frequencies lying within the range of human hearing: approximately 20 to 20,000 Hz.
  • Audit Trails: A record of events on the network including when users requested specific resources.
  • AUI Cable: See Attachment Unit Interface
  • AUP: See Acceptable Use Policy
  • Authentication: Any process that ensures that users are who they say they are. When you type your name & password, you are authenticated & allowed access.
  • Automatic Calling Unit: (ACU) The device attached to the sending DTE that facilitates dialing of a receiving DTE. It automatically performs the dialing function eliminating the need to manually dial the receiving DTE.
  • Automatic Request for Retransmission: (ARQ) A communications feature in which the receiver asks the transmitter to resend a block or frame, generally because of errors detected by the receiver.
  • AWG: See American Wire Gauge
  • AWM: Appliance Wiring Material.
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