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 datagrams.
- Negative acknowledgment.
Response sent from a receiving device to a sending device indicating
that the information received contained errors. Compare to acknowledgment.
Name Binding Protocol
- See NBP.
name caching
- Method by which remotely discovered
host names are stored by a router for use in future
packet-forwarding decisions to allow quick access.
name resolution
- Generally, the process of associating
a name with a network location.
name server
- Server connected to a network that
resolves network names into network addresses.
- Network access point.
Location for interconnection of Internet service providers in the
United States for the exchange of packets.
narrowband
- See baseband.
Narrowband ISDN
- See N-ISDN.
National Bureau of Standards
- See NBS.
National Institute of Standards and
Technology
- See NIST.
National Research and Education
Network
- See NREN.
National Science Foundation
- See NSF.
National Science Foundation Network
- See NSFNET.
native client interface architecture
- See NCIA.
- Network addressable unit.
SNA term for an addressable entity. Examples include LUs, PUs, and
SSCPs. NAUs generally provide upper-level network services. Compare
with path
control network.
- 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.
- Nonbroadcast multiaccess.
Term describing a multiaccess network that either does not support
broadcasting (such as X.25) or in which broadcasting is not feasible
(for example, an SMDS broadcast group or an extended Ethernet that
is too large). See also multiaccess
network.
- Name Binding Protocol.
AppleTalk transport-level protocol that translates a character
string name into an internetwork address.
- National Bureau of Standards.
Organization that was part of the U.S. Department of Commerce. Now
known as NIST. See also NIST.
- 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 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 obviates the need for a standalone
gateway and can provide flexible TCP/IP access while preserving the
native SNA interface to the host.
- Network Control Program.
In SNA, a program that routes and controls the flow of data between
a communications controller (in which it resides) and other network
resources.
NCP/Token Ring Interconnection
- See NTRI.
- Neighborhood discovery.
Process that runs on the NP of each LightStream 2020 ATM switch in
the ATM network. For call routing purposes, every node in the
network needs to know about changes in network topology, such as
trunks and ports going up or down. ND learns about such changes at
the chassis level and forwards this information to the GID process,
which sends the information throughout the network. Sometimes
referred to as neighborhood discovery daemon, or NDD.
See also GID.
NDD
- Neighborhood discovery daemon.
See ND.
- Network driver interface
specification. Specification for a generic, hardware- and
protocol-independent device driver for NICs. Produced by Microsoft.
nearest active upstream neighbor
- See NAUN.
- Regional network in New England
(United States) that links Boston University, Harvard University,
and MIT. Now part of BBN Planet. See also BBN
Planet.
negative acknowledgment
- See NAK.
neighborhood discovery
- See ND.
neighborhood discovery daemon
- See ND.
neighboring routers
- In OSPF, two routers that have
interfaces to a common network. On multiaccess networks, neighbors
are dynamically discovered by the OSPF Hello protocol.
- Network entity title.
Network addresses, defined by the ISO network architecture, and used
in CLNS-based networks.
net
- Short for network.
- Network Basic Input/Output
System. API used by applications on an IBM LAN to request
services from lower-level network processes. These services might
include session establishment and termination, and information
transfer.
NETscout
- Cisco network management application
that provides an easy-to-use GUI for monitoring RMON statistics and
protocol analysis information. NETscout also provides extensive
tools that simplify data collection, analysis, and reporting. These
tools allow system administrators to monitor traffic, set
thresholds, and capture data on any set of network traffic for any
segment.
NetView
- IBM network management architecture
and related applications. NetView is a VTAM application used for
managing mainframes in SNA networks. See also VTAM.
NetWare
- Popular distributed NOS developed by
Novell. Provides transparent remote file access and numerous other
distributed network services.
NetWare Link Services Protocol
- See NLSP.
NetWare Loadable Module
- See NLM.
- 1.) Collection of computers, printers,
routers, switches, and other devices that are able to communicate
with each other over some transmission medium. 2.) Command that
assigns a NIC-based address to which the router is directly
connected. 3.) Command that specifies any directly connected
networks to be included.
network access point
- See NAP.
network access server
- See access
server.
- Network layer address referring to a
logical, rather than a physical, network device. Also called a protocol
address. Compare with MAC
address.
network addressable unit
- See NAU.
- Person responsible for the operation,
maintenance, and management of a network. See also network
operator.
- Network monitoring device that
maintains statistical information regarding the status of the
network and each device attached to it. More sophisticated versions
using artificial intelligence can detect, define, and fix problems
on the network.
Network Basic Input/Output System
- See NetBIOS.
Network Control Program
- See NCP.
network driver interface specification
- See NDIS.
network entity title
- See NET.
Network File System
- See NFS.
- Organization whose functions have been
assumed by the InterNIC. See InterNIC.
Network Information Service
- See NIS.
network interface
- Boundary between a carrier network and
a privately-owned installation.
network interface card
- See NIC.
- Layer 3 of the OSI
reference model. This layer provides connectivity and path
selection between two end systems. The network layer is the layer at
which routing occurs. Corresponds roughly with the path
control layer of the SNA model. See also application
layer, data
link layer, physical
layer, presentation
layer, session
layer, and transport
layer.
network management
- Generic term used to describe systems
or actions that help maintain, characterize, or troubleshoot a
network.
Network Management Processor
- See NMP.
network management system
- See NMS.
network management vector transport
- See NMVT.
Network-to-Network Interface
- See NNI.
network node
- See NN.
Network Node Interface
- See NNI.
Network Node Server
- SNA NN that provides resource location
and route selection services for ENs, LEN nodes, and LUs that are in
its domain.
network number
- Part of an IP address that specifies
the network to which the host belongs.
network operating system
- See NOS.
Network Operations Center
- See NOC.
- Person who routinely monitors and
controls a network, performing such tasks as reviewing and
responding to traps, monitoring throughput, configuring new
circuits, and resolving problems. See also network
administrator.
network processor card
- See NP
card.
network service access point
- See NSAP.
networking
- Connecting of any collection of
computers, printers, routers, switches, and other devices for the
purpose of communication over some transmission medium.
neutral wire
- Circuit wire that is connected to an
earth ground at the power plant and at the transformer.
Next Hop Resolution Protocol
- See NHRP.
- Network File System.
As commonly used, a distributed file system protocol suite developed
by Sun Microsystems that allows remote file access across a network.
In actuality, NFS is simply one protocol in the suite. NFS protocols
include NFS, RPC, XDR (External Data Representation), and others.
These protocols are part of a larger architecture that Sun refers to
as ONC. See also ONC.
- Next Hop Resolution Protocol.
Protocol used by routers to dynamically discover the MAC address of
other routers and hosts connected to a NBMA network. These systems
can then directly communicate without requiring traffic to use an
intermediate hop, increasing performance in ATM, Frame Relay, SMDS,
and X.25 environments.
- 1.) Network interface
card. Board that provides network communication
capabilities to and from a computer system. Also called an adapter.
See also AUI.
2.) See network
information center.
- 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.
- Narrowband ISDN.
Communication standards developed by the ITU-T for baseband
networks. Based on 64-kbps B channels and 16- or 64-kbps D channels.
Contrast with BISDN.
See also BRI,
ISDN,
and PRI.
- National Institute of
Standards and Technology. Formerly the NBS, this U.S.
government organization supports and catalogs a variety of
standards. See also NBS.
- NetWare Loadable Module.
Individual program that can be loaded into memory and function as
part of the NetWare NOS.
- NetWare Link Services Protocol. Link-state routing protocol based on IS-IS. The Cisco implementation of NLSP also includes MIB variables and tools to redistribute routing and SAP information between NLSP and other IPX routing protocols. See also IS-IS.
- Network Management Processor.
Processor module on the Catalyst 5000 switch used to control and
monitor the switch.
- Network management system.
System responsible for managing at least part of a network. An NMS
is generally a reasonably powerful and well-equipped computer such
as an engineering workstation. NMSs communicate with agents to help
keep track of network statistics and resources.
- Network management vector
transport. SNA message consisting of a series of vectors
conveying network management specific information.
- 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 ENs. The NN contains a
CP that manages the resources of both the NN itself and those of the
ENs and LEN nodes in its domain. NNs provide intermediate routing
services by implementing the APPN PU 2.1 extensions. Compare with EN.
See also CP.
- 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 interface between a public switch
and private one is defined by the UNI standard. Also, the standard
interface between two Frame Relay switches meeting the same
criteria. Compare with UNI.
- Command used to turn off
name-to-address translation in the router.
- Network Operations Center.
Organization responsible for maintaining a network.
- 1. Endpoint of a network connection or
a junction common to two or more lines in a network. 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 is sometimes
used generically to refer to any entity that can access a network,
and is frequently used interchangeably with device. See also host.
2. In SNA, the basic component of a network, and the point at which one or more functional units connect channels or data circuits.
noise
- Undesirable communications channel
signals.
nonbroadcast multiaccess
- See NBMA.
nonreturn to zero
- See NRZ.
nonreturn to zero inverted
- See NRZI.
- In AppleTalk, a router that must first
obtain, and then verify, its configuration with a seed router before
it can begin operation. See also seed
router.
- Resource-intensive OSPF area that
carries a default route, static routes, intra-area routes, interarea
routes, and external routes. Nonstub areas are the only OSPF areas
that can have virtual links configured across them, and are the only
areas that can contain an ASBR. Compare with stub
area. See also ASBR
and OSPF.
nonvolatile random-access memory
- See NVRAM.
- Term used to describe problems between
the hot and neutral wires on a power line. See common
mode.
normal response mode
- See NRM.
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.
- Network operating system.
Generic term used to refer to what are really distributed file
systems. Examples of NOSs include LAN Manager, NetWare, NFS, and
VINES.
Novell IPX
- See IPX.
npadmin account
- One of the four default user accounts
that are created in the factory on each LightStream 2020 ATM switch.
The npadmin account is for privileged users. Its default interface
is the CLI.
- Network processor card.
Main computational and storage resource for the LightStream 2020 ATM
switch. Each LightStream 2020 switch has one or two NPs. The second
card, if present, serves as a backup for the first. Each NP is
associated with a floppy disk drive for loading software and a hard
disk drive for storing software and configuration data. Each NP also
has an access card that provides an Ethernet port.
NP TCS monitoring module
- See NPTMM.
NP module
- On a LightStream 2020 ATM switch, the
combination of the NP card, the NP access card, and the disk
assembly. See also access
card, disk
assembly, and NP
card.
- NP TCS monitoring module. Process that
runs on the NP of every LightStream 2020 ATM switch in an ATM
network. NPTMM monitors the health of the system through the TCS and
coordinates switch cutover when redundant switch cards are present.
See also TCS.
- National Research and
Education Network. Component of the HPCC program designed
to ensure U.S. technical leadership in computer communications
through research and development efforts in state-of-the-art
telecommunications and networking technologies. See also HPCC.
- 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.
- Nonreturn to zero.
NRZ signals maintain constant voltage levels with no signal
transitions (no return to a zero-voltage level) during a bit
interval. Compare with NRZI.
- Nonreturn to zero inverted.
NRZI signals maintain constant voltage levels with no signal
transitions (no return to a zero-voltage level), but interpret the
presence of data at the beginning of a bit interval as a signal
transition and the absence of data as no transition. Compare with NRZ.
- Network service access point.
Network addresses, as specified by ISO. An NSAP is the point at
which OSI Network Service is made available to a transport layer
(Layer 4) entity.
- National Science Foundation.
U.S. government agency that funds scientific research in the United
States. The now-defunct NSFNET was funded by the NSF. See also NSFNET.
- National Science Foundation
Network. Large network that was controlled by the NSF and
provided networking services in support of education and research in
the United States, from 1986 to 1995. NSFNET is no longer in
service.
- 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.
null modem
- Small box or cable used to join
computing devices directly, rather than over a network.
- Nonvolatile RAM. RAM
that retains its contents when a unit is powered off. In Cisco
products, NVRAM is used to store configuration information.
NYSERNet
- Network in New York (United States) with a T1 backbone connecting NSF, many universities, and several commercial concerns.