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Glossary

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Network layer

In the OSI reference model, it is layer 3--the layer in which

routing is implemented, enabling connections and path selection between
two end systems. See also: Application layer, Data Link layer, Physical layer,
Presentation layer, Session layer, and Transport layer.

network segmentation

Breaking up a large network into smaller networks.

Routers, switches, and bridges are used to create network segmentation.

NFS

Network File System: One of the protocols in Sun Microsystems'

widely used file system protocol suite, allowing remote file access across a
network. The name is loosely used to refer to the entire Sun protocol suite,
which also includes RPC, XDR (External Data Representation), and other
protocols.

NHRP

Next Hop Resolution Protocol: In a nonbroadcast multiaccess

(NBMA) network, the protocol employed by routers in order to dynami-
cally locate MAC addresses of various hosts and routers. It enables sys-
tems to communicate directly without requiring an intermediate hop, thus
facilitating increased performance in ATM, Frame Relay, X.25, and
SMDS systems.

NHS

Next Hop Server: Defined by the NHRP protocol, this server main-

tains the next-hop resolution cache tables, listing IP-to-ATM address
maps of related nodes and nodes that can be reached through routers
served by the NHS.

nibble

Four bits.

NIC

network interface card: An electronic circuit board placed in a com-

puter. The NIC provides network communication to a LAN.

NLSP

NetWare Link Services Protocol: Novell's link-state routing pro-

tocol, based on the IS-IS model.

NMP

Network Management Processor: A Catalyst 5000 switch processor

module used to control and monitor the switch.

node address

Used to identify a specific device in an internetwork. Can be

a hardware address, which is burned into the network interface card or a log-
ical network address, which an administrator or server assigns to the node.

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