Glossary- N
A Data Communication Historical Series
By Bob Pollard

HOME                          INDEX

NAA Next Available Agent: A strategy for selecting an agent to handle a call. The strategy seeks to maintain an equal load across skill groups or services.

NACS:

NetWare Asynchronous Communication Services: Novell software that supports Novell's AIO and NASI programming interfaces. NACS promotes the sharing of communications resources, such as MODEM(s) asynchronous hosts, and X.25 network services.

NADF:

North American Directory Forum: Collection of organizations that offer, or plan to offer, public directory services in North America based on the ITU-T X.500 Recommendations.

NADN:

Nearest Active Downstream Neighbor: In Token Ring or IEEE 802.5 networks, the closest downstream network device from any given device that is still active.

NAGLE’S ALGORITHM:

Actually two separate congestion control algorithms that can be used in TCP-based networks. One algorithm reduces the sending window; the other limits small data-grams.

NAK:

Negative Acknowledgment: A Control Character transmitted by the receiving device; normally would cause the retransmission of the data just received.

1) In the BSC protocol, NAK indicates an error in the previous transmission block and that the receiver is ready to accept retransmission.

2) NAK represents the ‘not ready’ reply to a poll on a multipoint system.

NAM:

1) Number Assignment Module: A component in a wireless phone that stores the telephone number and ESN (Electronic Serial Number) of the phone

2) Network Applications Management: In a two-tier service bureau architecture, the ICM that receives route requests from the carrier network and forwards them to a Customer ICM (CICM). A NAM usually contains only a small configuration that allows it to directly route a subset of calls and dispatch the other requests to the appropriate CICM. The NAM receives route responses from the CICM(s) and forwards them to the carrier network.

NAME CACHING:  

Method by which remotely discovered host names are stored by a router for use in future packet-forwarding decisions; allows quick access

NAME RESOLUTION:

The process in which software translate between names that are easy for users to work with and numerical IP (Internet Protocol) addresses, which are difficult for users but necessary for TCP/IP (Transmission Control Protocol/Internet Protocol) communications. Name resolution can be provided by software components such as DNS (Domain Name System) or WINS.

NAME SERVER:

Server connected to a network that resolves network names into network addresses.

NAME SERVICES LOGIN:

Worldwide exclusive names that allow a device to log into the switch (switching computer)

NAMESPACE:

A set of unique names for resources or items used in a shared computing environment:

For Microsoft Management Console (MMC), the namespace is represented by the console tree, which displays all of the snap-ins and resources that are accessible to a console.

For Domain Name System (DNS), namespace is the vertical or hierarchical structure of the domain name tree. For example, each domain label, such as host1: microsoft.com, indicates a branch in the domain

NAMESPACE TREE:

See Label; Domain Name System (DNS); Resource

NANOG:

North American Network Operator's Group: Primary forum for information exchange among U.S. exchange point participants, Internet service providers, and end users.

NANOSECOND (NS):

One billionth of a second

NANP:

North American Numbering Plan

NAP:
Network Access Point: A high-speed interconnection service that gives Internet Service Providers access to the Internet infrastructure.

NARP:

NBMA Address Resolution Protocol: Functional subset of NHRP that returns only the address mappings of nodes that are connected directly to the NBMA network.

NARROWBAND:

A communications channel with a bandwidth less than a voice-grade channel. A voice grade channel has a bandwidth of 4000 Hz (usable approximately 300 to 3600Hz). This voice grade line (channel) could be divided into channels of lower frequencies, I.E. 300Hz channels, which would be considered Narrow-Band channels. With advances in network technology, narrow-band may be associated with any channel operating at less than 1.544Mbps, such as Narrow-band ISDN (NISDN).

NAS:

Network Access Server: Cisco platform, or collection of platforms, such as an Access-Path system, that interfaces between the packet world (example: the Internet) and the circuit world (example: PSTN).

NASI:

1) NetWare Asynchronous Support Interface.

2) NetWare Access Server Interface

NAT:

Network Address Translation: Is the translation of an Internet Protocol address (IP address) used in one network to a different IP address within another network. One network is designated the inside network and the other is the outside. NAT also conserves on the number of global IP addresses that a company needs and it lets the company use a single IP address in its communication with the world.

NATCO:

National Communications Switching Center

NATIONAL FACILITIES:

A packet-switched nonstandard facility selected for a given nations network, and may or may not be found on other networks.ATIONAL TELEVISION SYSTEMS COMMITTEE (NTSC):The Electronic Industries Association (EIA) division that prepared the specifications and standards, which were approved by the Federal Communications Commission in 1953, for commercial broadcasting; uses 525 lines and transmits 30 images, or scans, per second.

NATIVE CLIENT INTERFACE ARCHITECTURE:

SNA (Systems Network Architecture) applications-access architecture, developed by Cisco that combines the full functionality of native SNA interfaces at both the host and the client and provides the flexibility for leveraging TCP/IP backbones. NCIA encapsulates SNA traffic on a client PC or workstation, which provides direct TCP/IP access while preserving the native SNA interface at the end-user level.

NAU:

Network Addressable Unit: SNA term for an addressable entity; examples include LU, PU, and SSCP. NAU(s) generally provide upper-level network services.

See Network Addressable Unit

NAUN:

Nearest Active Upstream Neighbor: In Token Ring or IEEE 802.5 networks, the closest upstream network device from any given device that is still active.

NAVCOMPT:

Comptroller of the Navy

NAVSEA:

Naval Sea Systems Command

NBFCP:

NetBIOS Frames Control Protocol: Protocol that establishes and configures NetBIOS over PPP.

NBMA:

Non-Broadcast Multi-Access: Term describing a multi-access network that does not support broadcasting, such as X.25, or where broadcasting is not feasible, for example: An SMDS broadcast group or an extended Ethernet that is too large.

NBNS:

NetBIOS Name Service

NBP:

Name Binding Protocol: AppleTalk transport-level protocol that translates a character string name into the DDP address of the corresponding socket client. NBP enables AppleTalk protocols to understand user-defined zones and device names by providing and maintaining translation tables that map names to their corresponding socket addresses.

NBS/ICST:

National Bureau of Standards/Institute for Computer Sciences and Technology: The bureau assigned to develop data communications and computer processing ‘Federal Information Processing Standards (FIPS)’.

 

HTML coding for a non-breaking space: It is used in HTML between consecutive words on a web page to prevent those two words from being broken apart at the end of a line.

NCA:

National Computer Analysts: A computer software development company founded by Don Nothstein and other RCA engineers.

NCB:

Network Control Byte: Used by host application developers for debugging communications between a controlling host application and the Cisco VCO/4K.

NCC:

Network Control Center: A supervisory office or station assigned the diagnosis tasks for a data network.

NCCF:

See Network Communications Control Facility

NCCOSC:

Naval Command, Control & Ocean Surveillance Center

NCIA:

Native Client Interface Architecture: SNA applications-access architecture, developed by Cisco that combines the full functionality of native SNA interfaces at both the host and the client with the flexibility of leveraging TCP/IP backbones. NCIA encapsulates SNA traffic on a client PC or workstation, thereby providing direct TCP/IP access while preserving the native SNA interface at the end-user level. In many networks, this capability eliminates the need for a standalone gateway and can provide flexible TCP/IP access while preserving the native SNA interface to the host.

NCOIC:

Non-Commissioned Officer in Charge

NCP

1) Network Control Program: In SNA, a program that routes and controls the flow of data between a communications controller and other network resources.

2) Network Control Protocol: Series of protocols for establishing and configuring different network layer protocols, such as for AppleTalk over PPP.

3) Network Control Point: The process within the AT&T signaling network that sends routing requests to a Customer Routing Point (CRP), such as the network interface controller (NIC) within the ICM.

NCP / TOKEN RING INTERCONNECTION (NTRI):

Function used by ACF/NCP to support Token Ring-attached SNA devices. NTRI also provides translation from Token Ring-attached SNA devices to switched dial-up devices.

NCS:

National Communications System

NCSA:

National Center for Supercomputing Applications

NCSU:

Network Control Signaling Unit
NDE:

Net-Flow Data Report

NDIS:

Network Driver Interface Specification: Microsoft specification for a generic, hardware- and protocol-independent device driver for NIC(s)

NDMS NAVSEA:

Defense Message System - Naval Sea Systems Command

NDS:

Netscape Directory Server: A LDAP server

NE:

Network Element: In general, a NE is a combination hardware and software system that is designed primarily to perform a telecommunications service function. For example, a NE is the part of the network equipment where a transport entity, such as a line, path, or section, is terminated and monitored.
As defined by wavelength routing, a NE is the originating, transient, or terminating node of a wavelength path.

NEAR-END CROSSTALK (NEXT):

Crosstalk occurring at the source of the transmitted signal

NEAREST ACTIVE UPSTREAM NEIGHBOR (NAUN):

In Token Ring or IEEE 802.5 networks, the closest upstream network device from any given device that is still active.

NEARNET:

Regional network in New England, United States that links Boston University, Harvard University, and MIT: Now part of BBN Planet.

NEBS:

1) Network Equipment Building Standards

2) Network Equipment Building Systems: In OSS, the Bellcore requirement for equipment deployed in a central office environment; covers hardware, crafts person interface, thermal, fire resistance, handling and transportation, earthquake and vibration, airborne contaminants, grounding, acoustical noise, illumination, EMC, and ESD requirements.

NEC:

National Executive Committee

National Exhibition Centre (Birmingham)

NEC Corporation / Company

NEIGHBORHOOD:  

A grouping of subscribers, computers, and shared or private cable MODEM(s) associated with an account administered in the User Registrar Admin. A neighborhood contains settings for auto-provisioning MODEM(s) as shared or private through the User Registrar Subscriber.

NEIGHBORING ROUTERS:

In OSPF, two routers that have interfaces to a common network: On multi-access networks, neighbors are discovered dynamically by the OSPF Hello protocol.

NEMS:

Network Element Management Server

NET:

1) Acronym for Network

2) Network Entity Title: Network addresses, defined by the ISO network architecture; used in CLNS-based networks.

NETBEUI:

NetBIOS Extended User Interface: Enhanced version of the NetBIOS protocol used by network operating systems, such as LAN Manager, LAN Server, Windows for Workgroups, and Windows NT. NetBEUI formalizes the transport frame and adds additional functions. NetBEUI implements the OSI LLC2 protocol.

NETBIOS:

Network Basic Input/Output System: API used by applications on an IBM LAN to request services from lower-level network processes; services might include session establishment and termination, and information transfer.

NETBIOS EXTENDED USER INTERFACE (NetBEUI):

A Microsoft Networking protocol: It is usually used in small, department-size Local Area Networks (LAN) of 1 to 200 clients. It can use Token Ring source routing as its only method of routing. It is the Microsoft implementation of the NetBIOS standard.

NETFLOW:

A feature of some routers that allows them to categorize incoming packets into flows:This classification can be used to bypass some of the work of the router and accelerate its switching operation.

NETIQUETTE:

A term referring to ’etiquette’: Proper behavior on a network / Internet

NETIZEN:

Derived from the term citizen and Internet, someone who uses networked resources
NETSC:

U. S. Army designation for the Hancock ASC: ‘North East Telecommunications Switching Center

NETSCAPE:

A WWW browser and the name of a company: A browser that was originally based on the Mosaic program developed at the National Center for Supercomputing Applications (NCSA).

NETSCOUT:

Cisco network management application that provides an easy-to-use GUI for monitoring RMON statistics and protocol analysis information: NET-scout also provides tools that simplify data collection, analysis, and reporting. These tools allow system administrators to monitor traffic, set thresholds, and capture data on sets of network traffic for any segment.

NETVIEW:

IBM network management architecture and related applications: Net-View is a VTAM application used for managing mainframes in SNA networks.

NETWARE:

Popular distributed NOS developed by Novell: Provides transparent remote file access and numerous other distributed network services.

NETWORK:

Generally, a network can be any inter-connection of computer systems, devices and facilities.

1) Switched networks, in which the telephone dialed network is normally used for voice or data.

2) Any series of points connected by communications channels.

3) Dedicated, Leased or Private Networks reserved for the use of one user or customer.

NETWORKS (Past and Present):

Advance Research Projects Agency Network (ARPANET)

Automatic Digital Network (AUTODIN)

Automatic Secure Voice Communications Network (AUTOSEVOCOM)

Automatic Voice Network (AUTOVON)

Command Net

Common User Network

Communications Net

Communications Network

Computer Network

Defense Communications System (DCS)

Defense Data Network (DDN)

Defense Information Systems Network (DISN)

Defense Messaging System (DMS)

Defense Switched Network (DSN)

Emergency Broadcast System (EBS)

Integrated Digital Network (IDN)

Electronic Telecommunications Network (ETN)

Internet media

Joint Multi-channel, Trunking and Switching System

Joint Tactical Information Distribution System (JTIDS)

National Communications System (NCS)

National Information Infrastructure (NII)

Packet Switched Network (PSN)

Value Added Network (VAN)

Wide Area Network (WAN)

NETWORK ADAPTER:

A device that connects a computer to a network: This device is sometimes called an adapter card or network interface card.

NETWORK ADDRESS:

Network layer address referring to a logical, rather than a physical, network device

NETWORK ADDRESSABLE UNIT (NAU):

Basically refers to a host based Physical Unit (PU), Logical Unit (LU), or System Services Control Point (SSCP) in the IBM System Network Architecture (SNA) environment. Or any device connected.

NETWORK ADMINISTRATOR:

A person responsible for planning, configuring, and managing the day-to-day operation of the network: Network administrator is also called a system administrator.

NETWORK ANALYZER:

Hardware or software device offering various network troubleshooting features, including protocol-specific packet decodes, specific preprogrammed troubleshooting tests, packet filtering, and packet transmission.

NETWORK ARCHITECTURE:

The hardware, circuits and software configuration plan for a computer network presented by a particular manufacturer or vendor. Or an existing system defined configuration.

NETWORK BASIC INPUT / OUTPUT SYSTEM:

See NetBIOS

NETWORK BYTE ORDER:

Internet-standard ordering of the bytes corresponding to numeric values

NETWORK CARD DRIVER:

A device driver that works directly with the network card; acting as an intermediary between the card and the protocol driver. With AppleTalk network integration, the AppleTalk Protocol stack on the server is implemented as a protocol driver and is bound to one or more network card drivers.

NETWORK COMMUNICATIONS CONTROL FACILITY (NCCF):

An IBM computer program which enables users to monitor and control network operation

NETWORK CONTROL PROGRAM (NCP):

Refers to a Front End Processor (FEP) program designed to handle communications control and processing functions and represents an interface between the data communications network and host processor.

NETWORK FACILITIES:

A term used in the packet switching environment to describe two forms of standard facilities, such as the essential facilities found on all networks and additional facilities which may be present on one network, but omitted on another. Or the description of a hardware, circuits (lines) and software media that creates a network.

NETWORK INDICATOR:  

Determines the type of call that is being placed: 0 = international, 1 = reserved, 2= national and 3 = national spare.

NETWORK INTERFACE:

1) The point of interconnection between the Public Switched Telephone Network (PSTN) and privately-owned terminal equipment.

2) The point of interconnection between one network and another

NETWORK INTERFACE CARD (NIC):
An expansion board inserted into a computer that connects the computer to a network. The NIC may be designed for a particular type of network, protocol, and media; although some can be designed to serve multiple networks.

NETWORK INTERFACE MACHINE (NIM):

Refers to a form of protocol converter used to adapt an X.25 packet network to non-packet mode terminals.

NETWORK LAYER:

Generically, any of several functions in a communications network, such as Terminal, Switching and Transmission

Layer 3: The third entity (layer) in the Open Systems Interconnection (OSI) model that is responsible for addressing and routing between sub networks and servicing the transport layer

NETWORK MANAGEMENT:  

Generic term used to describe systems or actions that help maintain, characterize, or troubleshoot a network.

NETWORK MANAGEMENT PROCESSOR (NMP):

Processor module In the Catalyst 5000 switch used to control and monitor the switch

NETWORK NAME RESOURCE:

The name of a device that exists on a network and is supported as a cluster resource by a Resource DLL (Dynamic Link Library) provided with Windows.

NETWORK NEWS TRANSFER PROTOCOL (NNTP):

A member of the TCP/IP (Transmission Control Protocol/Internet Protocol) suite of protocols used to distribute network news messages to NNTP servers and clients (newsreaders) on the Internet. NNTP is designed so that news articles are stored on a server in a central database, thus enabling a user to select specific items to read.

NETWORK NODE MANAGER (NNM):

A program that helps a network administrator manage the functional and operational conditions in a computer network. Using the Network Node Manager, an administrator can view the network in an easy-to-see graphical format and can monitor the status and location of each device in the network. When a device fails, NNM can analyze events associated with the failure and recommend action. Also some predictive information is provided that helps identify potential failures before they occur.

NETWORK NODE SERVER:

SNA NN that provides resource location and route selection services for EN(s)), LEN nodes, and LU(s) that are in its domain

NETWORK NUMBER:

Part of an IP address that specifies the network to which the host belongs

NETWORK NUMBERING EXCHANGE:

Descriptive of the physical and logical relations of nodes in a network; the schematic arrangement of the links and nodes; often classed as star, ring, tree or bus topology.

NETWORK OPERATOR:

Person who routinely monitors and controls a network: Performs such tasks as reviewing and responding to traps, monitoring throughput, configuring new circuits, and resolving problems.

NETWORK PARTITION:

A state in which one or more of the nodes in a cluster cannot communicate with the other cluster nodes

NETWORK PASSWORD:

A password that is used to log on to a network

NETWORK PORT:

In the context of wavelength routing: A port that tandems through the node; it is a port on the NE that points to another wavelength router.

NETWORK PROBLEM DETERMINATION APPLICATION (NPDA):

Refers to an IBM computer (host) based program designed to aid in the isolation and diagnosis of network problems.

NETWORK PROTOCOL:

The language a computer uses to communicate over a network. For a computer to communicate with another computer, they both must use the same protocol.

NETWORK SERVICE:

Services such as file and printer sharing on the computer or automatic backup to a network server.

May refer to the provided service within the Network Addressable Unit (NAU) of an IBM System Network Architecture SNA environment, which controls network operations through sessions to and from the host computer System Services Control Point (SSCP); or the term may refer to any network services environment.

NETWORK TERMINAL NUMBER:

See NTN

NETWORK TERMINAL OPTION (NTO):

An IBM System Network Architecture (SNA) program that allows non-SNA asynchronous and Binary Synchronous (BSC) devices to access the network via a communications control unit.

NETWORK TOPOLOGY:

An outline (description) of all network nodes, circuits and equipment, and their physical/logical relationship, such as ring, bus, star, etc.

NETWORK TRUNKS:

Refers to circuits connecting switching centers

NETWORK USER IDENTIFICATION:

See NUI

NETWORK VIRTUAL TERMINAL:

The usage of numerous data terminals operating with different protocols, formats, data rates and codes on the same network.

NEUTRAL CURRENT L0OP:

See current loop.

NEWBIE or NEWBY:

A newcomer to the internet who reveals his or her inexperience by lack of knowledge of internet conventions: netiquette, vocabulary, and know-how.

NEW TECHNOLOGY FILE SYSTEM (NTFS):

See NTFS

NEWSGROUP:

An electronic forum where readers post articles and follow-up messages on a specified topic: An Internet newsgroup allows people around the globe to discuss common interests. Each newsgroup name indicates the newsgroup's subject in terms of narrow categories, such as: alt.comp.virus.

NEXT:

Near-End Cross Talk: Interference between pairs of lines at the telephone switch (exchange) end.
NFAS:

Non-Facility Associated Signaling: A classification of signaling protocols that provide the signaling channel on a separate physical line from the bearer channels.

NFS:

Network File System: As commonly used, a distributed file system protocol suite developed by Sun Microsystems that allows remote file access across a network. NFS is one protocol in the suite. NFS protocols include NFS, RPC, XDR, and others. These protocols are part of a larger architecture that Sun refers to as ONC.

NHRP:

Next Hop Resolution Protocol: Protocol used by routers to dynamically discover the MAC address of other routers and hosts connected to an NBMA network. These systems then can communicate directly without requiring traffic to use an intermediate hop, increasing performance in ATM, Frame Relay, SMDS, and X.25 environments.

NHS:

Next Hop Server: Server defined by the NHRP protocol that maintains next-hop resolution cache tables containing the IP-to-ATM address mappings of associated nodes and nodes that are reachable through routers served by the NHS.

NIBBLE:

A term used to identify the last or first four bits of an eight-bit byte

NIC:

1) Network Interface Card: A printed circuit board installed into a network device. When the card is cabled, the NIC allows the device to communicate on a network. Or Network Information Center: Generally, any office that handles information for a network.

2) Network Information Center: Generally, any office that handles information for a network. The most famous of these on the Internet was the Inter-NIC, which was where most new domain names were registered until that process was decentralized to a number of private companies.

NID:

Network Interface Device: A device that terminates a copper pair at a user’s office, which is extended from the serving central office.

NIM:

See Network Interface Machine

NIS:

Network Information Service: Protocol developed by Sun Microsystems for the administration of network-wide databases. The service essentially uses two programs: one for finding a NIS server and one for accessing the NIS databases.

N-ISDN:

Narrowband ISDN: Communication standards developed by the ITU-T for base-band networks; based on 64-kbps B channels and 16- or 64-kbps D channels.

NIST:

National Institute of Standards and Technology: U.S. government organization that supports and catalogs a variety of standards; formerly the NBS.

NLC:

Node Line Card: One of the component cards used in the Cisco 6400 universal access controller. These cards provide the interfaces for moving data into and out of the Cisco 6400 system. They can be used as either uplink or downlink interfaces. Different types of line cards support different transmission protocols and data rates.

NLESO:

Network-level Extended Security Option: NLESO processing requires that security options be checked against configured allowable information, source, and compartment bit values; and requires that the router be capable of inserting extended security options in the IP header.

NLM:

NetWare Loadable Module: Individual program that can be loaded into memory and can function as part of the NetWare NOS.

NLOS:

Non Line of Sight: Also known as obstructed path or pathway

NLRI:

Network Layer Reach-ability Information: BGP sends routing update messages containing NLRI to describe a route and how to get there. In this context, an NLRI is a prefix. A BGP update message carries one or more NLRI prefixes and the attributes of a route for the NLRI prefixes; the route attributes include a BGP next hop gateway address, community values, and other information.

NLSP:

1) NetWare Link Services Protocol: Link-state routing protocol based on IS-IS.

2) Network Layer Security Protocol: OSI protocol (IS0 11577) for end-to-end encryption services at the top of OSI layer 3. NLSP is derived from an SDNS protocol, SP3, but is much more complex.

NMA:

Network Management and Analysis: Bellcore OSS providing alarm surveillance and performance monitoring of intelligent network elements.

NME:

Network Management Ethernet: The LAN used to control and manage equipment in a central office and branch locations.

NMP:

Network Management Processor: Processor module on the Catalyst 5000 switch used to control and monitor the switch.

NMS:

Network Management System: System responsible for managing at least part of a network. An NMS is generally a powerful and well-equipped computer, such as an engineering workstation. NMS(s) communicate with agents to help keep track of network statistics and resources.

NMVT:

Network Management Vector Transport: SNA message consisting of a series of vectors conveying specific network management information.

NN:

1) National Number: Part of a numbering plan.

2) Network Node: SNA intermediate node that provides connectivity, directory services, route selection, intermediate session routing, data transport, and network management services to LEN nodes and EN(s). The NN contains a CP that manages the resources of both the NN itself and those of the EN(s) and LEN nodes in its domain. NN(s) provide intermediate routing services by implementing the APPN PU 2.1 extensions.

NNI:

1) Network-to-Network Interface. ATM Forum standard that defines the interface between two ATM switches that are both located in a private network or are both located in a public network. The UNI standard defines the interface between a public switch and a private one.

2) Network Node Interface

NNTP:

Network News Transport Protocol: The protocol used by client and server software to carry USENET postings back and forth over a TCP/IP (Transmission Control Protocol / Internet Protocol) network. When any of the more common software such as Netscape, Nuntius, Internet Explorer, etc. is used to participate in newsgroups then it’s probable that a NNTP connection is in effect.

NNX CODES:

The 3-digit code used for local telephone exchange prefixes

NOA:

Nature of Address

NOC:

Network Operations Center: Organization responsible for maintaining a network

NODE:

Any device or data switching and/or processing system connected to a network. An inter-connection point to a data communications network

1) In a packet-switched environment, one of the switches that forms the networks backbone.

2) Any unit that is polled on a multipoint network.

3) A LAN (Local Area Network) station or any unit on a ring topology.

4) Endpoint of a network connection or a junction common to two or more lines in a network.

5) H.323 entity that uses RAS to communicate with the gatekeeper, for example, an endpoint such as a terminal, proxy, or a gateway.

6) In SNA, the basic component of a network and the point at which one or more functional units connect channels or data circuits.

7) A node is a point of connectivity, or wavelength router, where multiple fiber links come together into one point, and/or a source or a destination for a wavelength path.

   Nodes can be processors, controllers, or workstations. Nodes, which vary in routing and other functional capabilities, can be interconnected by links, and serve as control points in the network. Node sometimes is used generically to refer to any entity that can access a network, and frequently is used interchangeably with device.

NOISE:

Unwanted signals (interference) on a channel (line)

NOISE SUPPRESSER:

A device designed to minimize or eliminate noise in a data communications circuit. This could be accomplished through a filtering device, regenerator, relay, or other signal processing activity.

NON-BLOCKING:

A term used to identify the permanent connection of a device through a switching mechanism where a continuous path exists to that device.

NONBROADCAST MULTIACCESS:

See NBMA

NONCE:

Random or non-repeating value that is included in data exchanged by a protocol; usually for the purpose of guaranteeing live-ness and thus detecting and protecting against replay attacks.

NONDEDICATED:

A term used to describe a file server that can be used simultaneously as a workstation. File server functions run in the background when it is used as a workstation.

NON-ERASABLE:

Computer memory or storage that is not erasable: See ROM.

NONEXTENDED NETWORK:

AppleTalk Phase 2 network that supports addressing of up to 253 nodes and only 1 zone

Non-repudiation service

NON-IMPACT PRINTER:

A non-mechanical printing device that uses heat (thermal), light (laser), ink jet or other means (electrostatic), to produce printed output rather than a key or mechanical striking action.

NON-INTERACTIVE SYSTEM:

A computing system where the computer functions independently of the user during program execution

NON-LINEAR DISTORTION:

A form of line (signal) distortion (clipping) caused by signal level attenuation.

NON-PERSISTENT:

Term used in a Local Area Network (LAN) environment to define a Carrier Sense Multiple Access (CSMA) method where, in the event of a collision, the stations do not attempt an immediate retransmit, even if the communications network is available.

NON-PLUG AND PLAY:

A device, such as a printer, MODEM or game controller, that requires manual configuration of hardware settings before it can be used. Non-Plug and Play devices are becoming increasingly rare as manufacturers stop producing them in favor of Plug and Play devices. Non-Plug and Play typically applies to older pieces of equipment.

NON-RESTRICTED TOKEN:

A token denoting the normal mode of asynchronous bandwidth allocation, wherein the available bandwidth is time-sliced (multiplexed) among all requesters.

NON-RETURN to ZERO:

See NRZ

NON-RETURN to ZERO INVERTED:

See NRZI

NONSEED ROUTER:

In AppleTalk, a router that must first obtain, and then verify its configuration with a seed router before it can begin operation.

NON-TRANSPARENT MODE:

Refers to a mode in binary-synchronous protocol, where control characters and control sequences are recognized through the examination of all transmitted data.

NONSUB AREA:

Resource-intensive OSPF area that carries a default route, static routes, intra-area routes, inter-area routes, and external routes: Non-stub areas are the only OSPF areas that can have virtual links configured across them, and are the only areas that can contain an ASBR.

NON-SYNCHRONOUS:

See Asynchronous

NON-VOLATILE:

Refers to a computer memory or storage device that can retain the stored information when the power is interrupted or turned off; See ROM. Data in memory, cache and other electronic storage may be protected by a battery backup system to prevent their loss in the event of a power failure.

NONVOLATILE RANDOM ACCESS MEMORY:

See NVRAM

NORMALLY CLOSED / NORMALLY OPEN (released) CONTACTS:

The closed or open contacts on an un-operated relay

NORTH AMERICAN TELEVISION SYSTEMS COMMITTEE (NTSC):

The committee that standardizes television transmission signals in the U.S. and Canada. NTSC defined the broadcast system used in North America and other parts of the world. It uses 525 lines per screen and transmits 30 images, or scans, per second.

NORTHWEST NET:

NSF-funded regional network serving the Northwestern United States: Alaska, Montana, and North Dakota. Northwest Net connects all major universities in the region as well as many leading industrial concerns.

NOS:

Network Operating System: Generic term used to refer to distributed file systems. Examples of NOS(s) include LAN Manager, NetWare, NFS, and VINES.

NOT IN THE WILD:

Viruses ‘not in the wild’ are in the real world but fail to spread successfully.

NOTIFICATION AREA:

The area on the taskbar to the right of the taskbar buttons. The notification area displays the time and can also contain shortcuts that provide quick access to programs, such as Volume Control and Power Options. Other shortcuts can appear temporarily, providing information about the status of activities. For example: the printer shortcut icon appears after a document has been sent to the printer and disappears when printing is complete.

NOTIFICATION CODE:

Defines the severity assigned to a given condition under a specific set of circumstances

NPA:

Numbering Plan Area: The ‘area code’ of a North American Dialing Plan number

NPDA:

See Network Problem Determination Application

NPI:

Number Plan Identification

NR:

Network Registrar: Same as CNR. Network Registrar provides Domain Name Server (DNS) and DHCP services. Network Registrar supplies IP addresses and configuration parameters to DOCSIS cable MODEM(s) and PCs based on network and service policies, and allocates host names for these devices in DNS.

NREN:

National Research and Education Network: A component of the HPCC program designed to ensure U.S. technical leadership in computer communications; involves research and development efforts in state-of-the-art telecommunications and networking technologies.

NRM:

Normal Response Mode: HDLC mode for use on links with one primary station and one or more secondary stations. In this mode, secondary stations can transmit only if they first receive a poll from the primary station.

NRZ:

Non-Return to Zero: A transmission method where zeros and ones are represented by opposite high and low voltages. There are two basic forms of NRZ coding:

1) In a Uni-polar NRZ code the voltages would vary between 0v and +5V. This works well for shielded and short travel paths, but is not suited for long distances.

2) In a Polar NRZ code, less power (one half) would normally be required to transmit the signal, for example +2.5V and -2.5V.

NRZI:

Non-Return to Zero Inverted: May be referred to as invert-on-zero coding; NRZI is a Synchronous Data Link Control (SDLC) encoding technique where a change in state (signal/bit) represents a binary 0 and no change represents a binary 1.

NS:

Nanosecond: one-billionth of a second

NSA:

1) National Systems Analysts: A software production company.

2) Non-Service-Affecting: A category of conditions that do not interrupt payload traffic

NSAP:

Network Service Access Point: Network addresses, as specified by ISO. The NSAP is the point at which OSI network service is made available to a transport layer (Layer 4) entity.

NSB:

Network Status Byte: A byte returned by the Cisco VCO/4K to the controlling host to indicate the successful completion of transmission or error status of command processing.

NSF:

National Science Foundation: A US government agency that funded the development of a cross-country backbone network as well as regional networks designed to connect scientists to the Internet. It operates a US network, the National Science Foundation Network (NSFNET).

NSFNET:

National Science Foundation Network: An Internet type network that links government agencies, supercomputer centers, universities, and industry research organizations across the world.

NSLOOKUP:

A common Internet utility like ping or traceroute: Given an IP address or DNS address it will look up and show the corresponding DNS or IP address. There are nslookup utility programs available for every operating system, which a person can use with a PPP, networked or shell account.

NTFS:

New Technology File System: An advanced file system that provides performance, security, reliability, and advanced features that are not found in any version of FAT (File Allocation Table). For example, NTFS guarantees volume consistency by using standard transaction logging and recovery techniques. If a system fails, NTFS uses its log file and checkpoint information to restore the consistency of the file system. In Windows 2000 and Windows XP, NTFS also provides advanced features such as file and folder permissions, encryption, disk quotas, and compression.

NTN:

Network Terminal Number: An identity number that can be up to 10 digits in length, used by a Data Terminal Equipment (DTE) device, which identifies the logical location, and in some cases, may be a sub-address used only by the DTE and not the communications network.

NTO:

See Network Terminal Option

NT-1:

Network Termination 1: In ISDN, a device that provides the interface between customer premises equipment and central office switching equipment

NTP

Network Time Protocol: Protocol built on top of TCP that ensures accurate local time-keeping with reference to radio and atomic clocks located on the Internet. This protocol is capable of synchronizing distributed clocks within milliseconds over long time periods.

NTRI:

NCP/Token Ring Interconnection: Function used by ACF/NCP to support Token Ring-attached SNA devices. NTRI also provides translation from Token Ring-attached SNA devices (PUs) to switched (dial-up) devices.

NTSC:

1) North American Television Systems Committee

2) National Television Systems Committee: A United States TV technical standard, named after the organization that created the standard in 1941.

See National Television Systems Committee

N2 COUNT:

The allowable number of re transmissions (count) in a X.25 packet switched network.

NUI:

Network User Identification: A replacement for the Network Terminal Number (NTN) in newer X.25 packet-switched networks, the NUI combines the network users address and password.

NULL CHARACTER(s)

A filler, delete or idle character (all 1 bits/mark) that is inserted into a data stream to allow time for device mechanical actions (form feed, carriage return, etc.) which allows the device to be ready to process the next data character.

NULL ENCRYPTION ALGORITHM:

Algorithm [RFC 2410] that does nothing to transform plaintext data; that is, a no-op. It originated because of IP-sec ESP, which always specifies the use of an encryption algorithm to provide confidentiality. The NULL encryption algorithm is a convenient way to represent the option of not applying encryption in ESP (or in any other context where this is needed).

NULL MODEM:

See MODEM eliminator.

NULL MODEM CABLE:

Special cabling that eliminates the MODEM requirement for asynchronous communications between two computers over short distances. A null modem cable emulates MODEM communication.

NUMBER SYSTEM:

Any system for representing numbers; four number systems available are: decimal (base 10), hexadecimal (base 16), octal (base 8) and binary (base 2).

NUMBERING PLAN AREA (NPA) / NPA CODE:

A geographical division in the North American telephone numbering plan; no two telephones will have the same 7 digit number.

NVE:

Network-Visible Entity: Resource that is addressable through a network. Typically, a NVE is a socket client for a service available in a node.

NVRAM:

Nonvolatile RAM: RAM that retains its contents when a unit is powered off.

NXX CODES:

The current general configuration for Telephone Exchange Codes within each Area Code

NYQUIST THEORY:

A communications theory or process: Uses a two-sample per cycle process to characterize an analog signal limited by bandwidth. The rate of sampling must be twice the highest frequency component of the analog signal; for example, a 4000 Hz analog signal would be sampled 8000 times.

NYSERNET:

Network in New York (United States) with a T1 backbone connecting the NSF, many universities, and several commercial concerns

NZ-DSF:

Non Zero-Dispersion-Shifted Fiber: A dispersion shifted SM fiber that has the zero dispersion point near the 1550 nm window; outside the window is actually used to transmit signals.