IBM SY27-0345-06, Руководство по обслуживанию и ремонту

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MTU. Maximum transmission unit.
N
NetBIOS. Network Basic Input/Output System. An
operating system interface for application programs
used on IBM personal computers that are attached to
the IBM Token-Ring Network. See also
BIOS.
network. (1) A configuration of data processing
devices and software connected for information inter-
change. (2) A group of nodes and the links intercon-
necting them.
network administrator. A person who manages the
use and maintenance of a network.
O
Open Systems Interconnection (OSI). (1) The inter-
connection of open systems in accordance with stand-
ards of the International Organization for
Standardization (ISO) for the exchange of
information. (T) (A) (2) The use of standardized proce-
dures to enable the interconnection of data processing
systems.
Note: OSI architecture establishes a framework for
coordinating the development of current and future
standards for the interconnection of computer systems.
Network functions are divided into seven layers. Each
layer represents a group of related data processing and
communication functions that can be carried out in a
standard way to support different applications.
optical wrap. Signal transmission, used primarily for
testing, that routes the signal from the optical output of
a device directly to the optical input.
OSI. Open Systems Interconnection.
P
Point-to-Point Protocol (PPP). A protocol that pro-
vides router-to-router and host-to-host network con-
nections over both synchronous and asynchronous
circuits.
port. (1) An access point for data entry or exit. (2) A
connector on a device to which cables for other devices
such as display stations and printers are attached.
Synonymous with
socket. (3) The representation of a
physical connection to the link hardware. A port is
sometimes referred to as an adapter; however, there
can be more than one port on an adapter. There may
be one or more ports controlled by a single DLC
process.
POST. Power-on self-test.
PPP. Point-to-Point Protocol.
problem determination. The process of determining
the source of a problem; for example, a program com-
ponent, machine failure, telecommunication facilities,
user or contractor-installed programs or equipment,
environmental failure such as a power loss, or user
error.
processor. In a computer, a functional unit that inter-
prets and executes instructions. A processor consists
of at least an instruction control unit and an arithmetic
and logic unit. (T)
Q
queue. A list constructed and maintained so that the
next data element to be retrieved is the one stored
first. (T)
R
random access memory (RAM). (1) A storage device
in which data can be written and read. (2) A storage
device into which data is entered and from which data
is retrieved in a nonsequential manner. (3) Deprecated
term for
direct access storage device. (T)
read-only memory (ROM). (1) A storage device in
which data, under normal conditions, can only be read.
(T)
(2) Memory in which stored data cannot be modi-
fied by the user except under special conditions.
ring. (1) Two or more stations in which information is
passed sequentially between active stations, each
station in turn examining or copying the information,
finally returning it to the originating station. (2) See
ring
network.
ring network. (1) A network in which every node has
exactly two branches connected to it and in which there
are exactly two paths between any two nodes. (T)
(2) A network configuration in which devices are con-
nected by unidirectional transmission links to form a
closed path.
ROM. Read-only memory. (A)
router. (1) A computer that determines the path of
network traffic flow. The path selection is made from
several paths based on information obtained from spe-
cific protocols, algorithms that attempt to identify the
shortest or best path, and other criteria such as metrics
or protocol-specific destination addresses. (2) An
attaching device that connects two LAN segments,
which use similar or different architectures, at the refer-
Glossary
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