Geek-Speak Glossary: A Manager’ s Guide to IT T er minolo gy

- Active hub: allows multiple devices to be wired to a central location to share the same media and regener- ate the signal.
- ADSL (asymmetric digital subscriber line): typical form of xDSL telephone companies offer to residences AGP (accelerated or advanced graphics port): a high-speed, point-to-point channel for attaching a graphics card to a computer’s motherboard, primarily to assist in the acceleration of 3D computer graphics ALU (arithmetic logic unit): a digital circuit that calculates an arithmetic operation (e.g., addition, subtrac- tion) and logic operations between two numbers.
- the fundamental building block of the Central Processing Unit (CPU) or a computer.
- AM (amplitude modulation): a technique used for transmitting information via a radio carrier wave Amplitude: height of the wave at any point in the wave.
- ANSI (American National Standards Institute): a voluntary organization that coordinates the develop- ment and use of consensus standards in the United States and represents the needs and views of U.S..
- used to map an IP (inter- net protocol) address to a MAC (media access card) address.
- digital signals are numbers sent in the Base 2 system.
- Bit: contraction of the expression “binary digit”.
- primary function is to prepare the machine so other software programs can load, execute, and assume control of the PC.
- Bricks and clicks: business that existed pre-Internet that now uses e-commerce technology to sell on the Internet.
- increases processor operation speed CAD/CAM (computer-aided design/computer-aided manufacturing): software used to design prod- ucts such as electronic circuit boards in computers.
- Checksum: a count of the number of bits in a transmission unit that is included with the unit so the receiver can check to see whether the same number of bits arrived.
- CIR (committed information rate): describes the user information transfer rate the network supports dur- ing normal network operations.
- information is centralized on the server, and an administrator sets policies and manages it.
- with one another for being sent on a shared medium, in particular in the Ethernet networking protocol.
- Connectivity devices: bring users of the network into contact with one another.
- used when the arrival of the information is time-sensitive.
- CPU (Central Processing Unit): the brain of the computer system where calculations and decisions are made.
- a function used to produce a Checksum against a block of data.
- can cross-connect any T1 line in the system with any other T1 line in the system.
- Data: information manipulated inside the computer in the form of bits and bytes.
- associated with the network layer when communica- tion protocol is connectionless.
- DDP (datagram delivery protocol): a member of the AppleTalk networking protocol suite, mainly respon- sible for socket-to-socket delivery of datagrams over an AppleTalk network.
- DE (discard eligibility): signal used to identify less important data traffic that can be dropped during peri- ods of congestion on the system.
- DLCI (data link connection identifier): a channel number that tells the network how to route the data.
- DMA (direct memory access): a feature that allows certain hardware subsystems in a computer to access system memory for reading and/or writing independently of the CPU.
- DNA (digital network architecture): a set of specifications or protocols created by Digital Equipment Corporation (DECnet) that evolved into one of the first peer-to-peer network architectures.
- widely used to transmit voice and data between devices DSL (digital subscriber line): technology that delivers digital data transmission over the wires of a local telephone network.
- DTE (data terminal equipment): a device that performs functions at the network end of a communica- tions line.
- EGP (exterior gateway protocol): a protocol commonly used between hosts on the Internet to exchange routing table information.
- EMI (electromagnetic interference): radiation that causes unwanted signals (interference or noise) to be induced in other circuits.
- also used to isolate one part of a network from another.
- Frame: data structure that collectively represents the transmission stream (headers, data, and the trailer) and provides the information necessary for the correct delivery of the data.
- FRAD (frame relay access device): software that frames the customer’s payload with the Frame Relay overhead information, including the first DLCI (data link connection identifier) address, to prepare it for deliv- ery to the network.
- FTP (file transfer protocol): application used to transfer a copy of a file from one computer to another computer with one acting as client and the other as server.
- Gateway routers: used to implement exterior protocols and interconnect autonomous systems.
- Hard drive: large data storage devices permanently mounted in the computer's case Hardware: physical devices located on a desk or in a server-room rack.
- Host-to-host layer: part of the TCP/IP model that performs the same function as the transport layer in the OSI model.
- Hubs: bring the users of the network into contact with one another.
- used to report errors and provide other information relevant to IP packet processing.
- IGMP (Internet group management protocol): a communications protocol used to manage the mem- bership of IP multicast groups.
- Interface: point in the system where the rules, control codes, formats, and information direction (as dictated by the protocol) are implemented.
- Internet layer: part of the TCP/IP model that performs the same function as the network layer of the OSI model.
- I/O (Input/output devices): hardware used to enter and retrieve data from the system.
- LAPB (link access protocol, balanced): a data link protocol in the X.25 stack.
- LATAs (local access and transport areas): In the US, refers to a geographic region assigned to one or more telephone companies for providing communication services.
- Layer 2 switches: interpret and make switching decisions on the LAN hardware adapter address contained in the data link header of MAC frames.
- forward frames only to the destination hardware address contained in the frame.
- LEC (local exchange carrier): a public telephone company in the US that provides local service.
- LGN (logical channel group number): together with the LCN (in the X.25 packet header), identifies the actual logical channel number of the DTE-DCE link.
- a 4-bit field representing a number between 0 and 15 Line layer: layer of the OSI physical layer that is responsible for synchronizing and multiplexing multiple streams of data into one SONET stream within SONET frames.
- LLC (logical link control): standard interface allowing any combination of MAC techniques and physical media to be used simultaneously in the same workstations.
- shields higher layer protocols from the peculiarities of the physical medium.
- to be useful in some way.
- Memory: desk space of the computer system.
- microchips located on the motherboard that hold data and instructions for the CPU (central processing unit).
- Message: information content to be shared.
- a megahertz is equal to one million cycles per second MIB (management information base): a type of database used to manage the devices in a communica- tions network.
- Multiport repeaters: allow multiple devices to be wired to a central location, share the same media, and regenerate (repeat) the signal.
- NAP (network access point): transitional data communications facilities at which Network Service Providers (NSPs) would exchange traffic, in replacement of the publicly-financed NSFNet Internet backbone;.
- part of the TCP/IP model that performs the same functions as the data link and physical layers of the OSI model.
- Network address: part of an IP address that is uniquely assigned by one of the ICANN-sanctioned agencies Network design: how the various clients and servers are arranged for purposes of connectivity, perform- ance, and security.
- negative voltage is used to represent a binary 1, and a positive voltage is used to represent a binary 0.
- OSI (open systems interconnection) model: developed to provide a view of the distinct functionalities that are required to implement each protocol layer.
- associated with the network layer when the communication protocol is connection-oriented.
- PAD (packet assembler/disassembler): assembles X25 packets on the sending end for transmission over the X25 PSDN, or disassembles X25 packets on the receiving end for onward transmission to the local network Parallel port: port where the bits travel down parallel paths, arriving one byte at a time.
- special form of repeater that allow multiple devices to be wired into a central location and share the same media.
- Path layer: layer of the OSI physical layer that is responsible for reliable end-to-end transport and payload delivery, including automatic recovery from failure points.
- Phase: where in the wave cycle the wave currently is.
- users on the network can freely share resources on their computer or access shared resources on other com- puters.
- Photonic layer: layer of the OSI physical layer that specifies fiber cable with optical light sources and receivers.
- POP (Post Office Protocol): how clients access their mailboxes on the messaging server.
- Process and application layer: Part of the TCP/IP model that performs the same functions as the applica- tion, presentation, and session layers of the OSI model.
- Processor: brain of the computer system where calculations and decisions are made.
- Processor memory: referred to as the L1 (level 1), an interface between the processor and the cache Protocol: set of rules used to control the exchange of information that is understood by the transmitter and receivers.
- Proxy server: sits between the network router and the Internet.
- talks to the Internet on behalf of a net- work’s resources, allowing real network addresses to be hidden.
- PSTN (public switched telephone network): the network of the world’s public circuit-switched tele- phone networks.
- in much the same way the Internet is the network of the worlds’ public IP-based.
- PVCs (permanent virtual circuits): use a real, shared circuit in the service provider’s backbone.
- RARP (reverse address resolution protocol): protocol used to resolve an IP address from a given hard- ware address (e.g., an Ethernet address).
- RAS (remote access service): allows users to access the network through dial-up modem connections Receiver: destination of the message or data.
- RIP (routing information protocol): used by routers connecting LANs to exchange routing table informa- tion to determine the best path through the network at any point in time.
- makes decisions about packet forwarding based on IP address information in the packet.
- RTMP (routing table maintenance protocol): a communication protocol used by AppleTalk to ensure that all routers on the network have consistent routing information.
- Section layer: layer of the OSI physical layer that creates frames, monitors the conditions of the transmission between the SONET equipment, and converts optical signals to and from electrical signals.
- Semaphores: messages sent when a file is opened that prevent other users from opening the same file at the same time and compromising the integrity of the data.
- however, no proxy is used between the network and the Internet.
- SNMP (simple network management protocol): application layer protocol in the TCP/IP family.
- implemented with centralized manage- ment stations that collect network information from agents throughout the network.
- SQL (structured query language): computer language used to create, retrieve, update, and delete data from relational database and/or object-relational database management systems.
- STM-1 (synchronous transport module, level 1): the basic rate of transmission of the SDH ITU-T fiber optic network transmission standard.
- Storage devices: means of storing data in the computer system for later retrieval and use.
- STS-1 (synchronous transport signal, level 1): base signal in SONET (synchronous optical network) Subnetting: logical segmentation of the network into smaller, more manageable parts.
- SVCs (switched virtual circuits): use a real, shared circuit path in the service provider’s backbone for the duration of the call or connection only.
- Switching: preferred method of interconnecting devices in the LAN environment.
- TCP/IP (transmission control protocol/Internet protocol): dominant protocol suite used in networking TCP (transport control protocol): connection-oriented, reliable protocol that has end-to-end responsibility for making sure that information arrives without errors and in the correct order.
- TDM (time-division multiplexing): used in the T1 frame format.
- Transport layer: layer that is responsible for delivering information in sequence and to the correct end-user Trap: SNMP protocol function used by the agent in a managed device to report important events or alarms Topology: the physical (how the wires are laid out) and/or logical (how the wires work) arrangement of the devices on the network.
- Wireless: telecommunications in which electromagnetic waves (rather than some form of wire) carry the sig- nal over part or all of the communication path

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