[N]

Nanosecond (NS, NSEC) – One-thousandth-millionth (or billionth) of a second. (10-9 second.)
Network – (1) System of mutually-communicating devices (for example: computers, terminals, peripheral devices, process controllers) connected in common and for a purpose by one or more transmission facilities. (2) A collection of switches connected to one another by transmission facilities.

Network Administrator – Departmental Staff member responsible for administering and maintaining a network.

Network architecture – The philosophy and organizational concept for enabling communications between equipment at multiple locations; detailed specifications outlining the processors, terminals and transmission media, protocols and software to be used to accomplish accurate communications.

Network layer – The logical network entity that services the transport layer in the OSI model. It is responsible for ensuring that data passed to it from the transport layer is routed and delivered through the network.

Network Operations Center (NOC) - The center responsible for monitoring network equipment. Usually a 24×365 operation.

Network ring-again - A feature on a PBX that allows a caller, after encountering a busy signal, to be notified when the called line becomes free, provides the option of automatically reinstating the call.

Network topology – (1) Describes the physical and logical relationship of nodes in a network. (2) The schematic arrangement of the links and nodes of a network, typically either a star, ring, tree or bus topology, or some hybrid combination thereof.

Network trunks – Circuits connecting switching centers.

Network virtual terminal – A communications concept wherein a variety of DTEs, with different data rates, protocols, codes, and formats, are accommodated in the same network. This is done as a result of network processing, where each device’s data is converted into a network standard format, then converted into the format of the receiving device at the destination end.

Nibble – Popular name for four bits, or half a byte. Also spelled nybble.

Node – (1) In network topology, a terminal of any branch of a network or a terminal common to two or more branches of a network. (2) In a switched network, the switching points, including patch and control facilities. (3) In a data network, the location of a data station which interconnects data transmission lines. (4) A point in a standing wave at which the amplitude is at a minimum. Synonyms: junction point, nodal point, vertex, null.

Noise – (1) Unplanned energy introduced onto a communications path, resulting in transmission errors. Undesirable signals bearing no desired information. (2) The unpredictable difference between the observed data and the true process.

Non-blocking – A switching network having a sufficient number of paths such that an originating call can always reach any other idle station without encountering a busy signal.

Nonvolatile storage – A medium that maintains or keeps its contents when the power is removed.

NNX (network numbering exchange) – Former three-digit location code which represented a central office. Now in NXX form, the available number of CO codes has been increased by permitting 0 and 1 as second digits in some circumstances. (See NXX.)

NPA (numbering plan area) – A geographical boundary within which no two telephones will have the same seven-digit number. “N” is any number between two and nine, “P” is always one or zero; and “A” is any number excluding zero. (2) Area code.

NXX (network numbering exchange) – An American Central Office Code where N is a digit 2 thru 9, and X is a digit 0 thru 9. Previously in NNX form, the available number of codes has now been increased by permitting 0 and 1 as second digits in some circumstances (previously their use was restricted to NPA codes).