IBM 5500 Operational, Installation, And Maintenance Manual page 182

fiber optics The branch of optical technology con-
cerned with the transmission of radiant power through
fibers made of transparent materials such as glass, fused
silica, and plastic.
H
half-duplex (HD, HDX) In data communication, per-
taining to transmission in only one direction at a time.
Contrast with duplex.
hard error An error condition on a network that
requires removing the source of the error or reconfigure
the network before the network can resume reliable
operation.
I
Initialization The first step taken to prepare an adapter
port for use after the computer has been booted. During
initialization, the adapter port runs a series of internal
self-diagnostic tests.
Internet Control Message Protocol (ICMP) The pro-
tocol used to handle errors and control messages in the
Internet Protocol (IP) layer. Reports of problems and
incorrect datagram destinations are returned to the origi-
nal datagram source.
integrated services digital network (ISDN) A digital
end-to-end telecommunication network that supports
multiple services including, but not limited to, voice and
data. ISDNs are used in public and private network
architectures.
L
local area network (LAN) (1) A computer network
located on a user's premises within a limited geographi-
cal area network is not subject to external regulations;
Communication within a local area network is not sub-
ject to external regulations; however, communication
across the LAN boundary may be subject to some form
of regulation.
(2) A network in which a set of devices are connected to
one another for communication and that can be con-
nected to a larger network.
(3) See Ethernet and token ring.
(4) Contrast with metropolitan area network and wide
area network
M
Glossary 182
Management Information Base (MIB) (1) A collec-
tion of objects that can be accessed by means of a net-
work management protocol.
(2) A definition for management information that speci-
fies the information available from a host or gateway
and the operations allowed.
Mbps Megabits per second (note case, should be Mbps)
MBps Megabytes per second (note case, should be
MBps)
MIB variable In the Simple Network Management Pro-
tocol (SNMP), a specific instance of data defined in a
MIB module.
multiplex To interleave or simultaneously transmit two
or more messages on a single channel.
multiplexer Devices that receive multiple port signals
from the host and transmit these signals across one link.
Multiplexers can also split multiple signals from one
link into multiple, single signal lines. These devices are
used in pairs: one at the host and one receiving.
N
NetView See TME 10 NetView and TME 10 NetView
for OS/390.
network management The process of planning, orga-
nizing, and controlling a communication-oriented data
processing or information system.
O
Open The state in which the adapter port has estab-
lished connection with other devices on the ring.
P
packet A self-contained group of bits representing data
and control information. The control information usu-
ally includes source and destination addressing,
sequencing, flow control, and error control information
at different protocol levels. Packet lengths can be fixed
or variable depending on the protocol.
ping Sending an ICMP Echo Request packet to a host or
gateway, with the expectation of receiving a reply. Ping-
ing is a method for confirming that devices on a network
are operating properly.
Point-to-Point Protocol (PPP) A protocol that pro-
vides a method for encapsulating and transmitting pack-
ets over serial point-to-point links.
protocol The meanings of, and the sequencing rules for,