Glossary N-O

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  • NA: See Numerical Aperture
  • NAK: See Negative Acknowledgment
  • Name Binding Protocol: (NBP) AppleTalk protocol for translating devices names to addresses.
  • Nanometer: (nm) One billionth of a meter = 10-9 meter.
  • Nanosecond: One billionth of a second.
  • National Electrical Code: (NEC) which defines building flammatory requirements for indoor cables.
  • National Television System Committee: (NTSC) One of the standards for television signals, developed in 1941. Has 486 visible horizontal lines.
  • NBP: See Name Binding Protocol
  • NCC: See Network Control Center
  • NDIS: See Network Driver Interface Specification
  • Near End Crosstalk: (NEXT) Crosstalk measured at the end from which the disturbing signal is transmitted.
  • NEC: See National Electrical Code
  • Negative Acknowledgment: (NAK) A data link control character transmitted by the receiver as a negative response to the sender. The response may relate to data or control information.
  • NEMA: National Electrical Manufacturers Association.
  • Neoprene: A synthetic rubber with good resistance to oil, chemical, & flame. Also called polychloroprene.
  • Net Id: See Network Identification
  • NetBIOS: See Network Basic Input/Output System
  • Netview: An IBM mainframe network management product that integrated the function of several earlier IBM network management products.
  • NetWare: Novell's network operating system using IPX (Internetwork Packet Exchange) & SPX (Sequential Packet Exchange) protocols.
  • Network: A set of communication channels inter-connecting several devices and/or locations.
  • Network Architecture: A description of data formats & procedures used for communication between nodes.
  • Network Basic Input/Output System: (NetBIOS) A widely-used protocol governing data exchange & network access.
  • Network Control Center: (NCC) Any centralized network diagnostic & management station or site, such as that of a packet-switching network.
  • Network Driver Interface Specification: (NDIS) Specification for a generic device driver for network interface cards that are independent of hardware & protocol.
  • Network File System: (NFS) Sun Microsystems' network operating system based on TCP/IP protocols.
  • Network Identification: (Net Id) The first part of the 32-bit IP address.
  • Network Information Frame: (NIF) determines which FDDI station is upstream & which is downstream when two stations are talking.
  • Network Interface Card: See Network Interface Controller
  • Network Interface Controller: (NIC) Electronic circuitry that connects a workstation to a network, usually a card that fits into one of the expansion slots inside a personal computer. It works with the network software & computer operating system to transmit & receive messages on the network.
  • Network Interface Module: See Adapter Card
  • Network Layer: Layer 3 of the OSI (Open Systems Interconnection) model; it defines protocols governing data routing.
  • Network Loadable Module: (NLM) An application or driver that resides on a NetWare server to provide additional resource management capabilities.
  • Network Management System: (NMS) Systems equipment used in monitoring, controlling & managing a data communications network.
  • Network Operating Systems: (NOS) Software that provides users with a variety of data communication service including file sharing, electronic mail, security systems & methods for connecting network systems.
  • Network Topology: The arrangement of nodes usually forming a star, ring, tree, or bus pattern.
  • NEXT: See Near End Crosstalk
  • NFS: See Network File System
  • NIC: See Network Interface Controller
  • NIF: See Network Information Frame
  • NIM: (Network Interface Module) See Adapter Card
  • NLM: See Network Loadable Module
  • NM: See Nanometer
  • NMS: See Network Management System
  • Nodes: A device connected to the network which can be addressed by other nodes.
  • Noise: In a cable or circuit, any extraneous signal which tends to interfere with the signal normally present in or passing through the system.
  • Non-Return to Zero: (NRZ) Binary coding transmission with no return to neutral state after each bit is transmitted.
  • Nondedicated server: A node on which user applications are available while network resources maintenance applications execute in the background.
  • NOS: See Network Operating Systems
  • NRZ: See Non-Return to Zero
  • NTSC: See National Television System Committee
  • Null Modem: A device that connects two DTE's directly by emulating the physical connections of a DCE.
  • Numerical Aperture: (NA) A measure of the angular acceptance for a fiber. It is approximately the sine of the half angle of the acceptance cone.
  • Nylon: An abrasion-resistant thermoplastic with good chemical resistance.
  • ODI: See Open Datalink Interface
  • Ohm: The electrical unit of resistance. The value of resistance through which a potential difference of one volt will maintain a current of one ampere.
  • Open Datalink Interface: (ODI) a standard interface specification developed by Novell to enable PC adapter cards to run multiple protocol stacks.
  • Open Shortest Path First: (OSPF) A distribution algorithm & routing protocol used by routers to compute the best path to be used to forward packets through an internetwork. It is derived from the OSI Shortest Path First (SPF) algorithm.
  • Open System: A networked computer or software which can easily be extended or enhanced with precuts from another vendor or technology source. Open systems usually imply the use of standard, replaceable protocols & hardware components, & well-defined interfaces.
  • Open Systems Interconnection: (OSI). A standard developed by the ISO (International Standards Organization) for a logical network operations structure.
  • Operating System: A program which controls the operation, scheduling & various other related functions of other programs within the computer.
  • Optical Disk: A very high-density information storage medium that uses light to read & write digital information.
  • Optical Fiber Cable: An assembly consisting of one or more optical fibers (glass or plastic) with strengthening material & an outer jacket.
  • Optical Fiber Duplex Connection: A mated assembly of two duplex connectors & a duplex adapter.
  • Optical Fiber Duplex Connector: A mechanical media termination device designed to transfer optical power between two pairs of optical fibers.
  • Optical Time Domain Reflection: An instrument that measures transmission characteristics of fiber by sending a pulse of light down the fiber & measuring the light scattered across the length & reflected back from the end as a function of time.
  • OS/2: The third generation operating system developed by IBM & Microsoft for use with the Intel 80286 & 80386 microprocessors. Unlike its predecessor (PC MS-DOS), OS/2 is a multitasking operating software that will run on the Personal System/2. OS/2 Standard Edition is a joint Microsoft & IBM development, while OS/2 Extended Edition is the IBM proprietary extension to include communications & database managers.
  • OSI: See Open Systems Interconnection
  • OSINET: A test network, sponsored by the National Bureau of Standards (NBS), designed to provide vendors of products based on the OSI model a forum for inter-operability testing.
  • OSPF: See Open Shortest Path First
  • Overhead: In communications, all information, such as control, routing, & error-checking characters, that is in addition to user transmitted data; includes information that carries network status or operational instructions, network routing information, & retransmission of user data messages that are received in error.
  • Ozone: Extremely reactive form of oxygen, normally occurring around electrical discharges & present in the atmosphere in small but active quantities. In sufficient concentrations it can break down certain rubber insulation's under tension (such as a bent cable).
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