Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)
Glossary 317
Glossary
events are to be logged. Class 1
(catastrophic event) is always
logged.
logical device number (ldev)
A value by which MPE/iX
recognizes a specific device. All
DTC devices that are configured
as nailed devices through the
NMMGR configuration have ldev
numbers permanently assigned.
The DTC devices can then be
accessed programmatically
through use of their ldev number.
Non-nailed devices have ldev
numbers that are assigned from a
pool of available ldev numbers for
the life of their connection to a
system. Each nailed port
configured in NMMGR must have
a unique ldev number.
log off The termination of a job
or session.
log on The process of initiating a
job or session.
logon device See
session-accepting device.
loopback The routing of
messages from a node back to
itself.
LUG Local User Group. A list
defined for a particular DTC and
card that specifies which remote
nodes this DTC can send data to
and also which remote nodes this
DTC can receive data from. See
also Closed User Group.
M
map, network A drawing that
shows the topology of the
network. For networks managed
by the OpenView DTC Manager a
network map must be created
through use of the OVDraw
capability provided with the
management software. A network
map is also a hardcopy drawing
used when planning a network. It
shows network topology, node and
network names, addresses,
network boundaries (for an
internetwork map), and link
types.
mapping A set of characteristics
that describe a route taken by
messages to reach a destination
node. This set of characteristics is
configured with NMMGR at every
node on a point-to-point network.
One mapping is configured at
each node for every other node on
the network to which messages
will be sent.
MAU Medium Attachment Unit.
A device attached to a ThickLAN
coaxial cable that provides the
physical and electrical connection
from the AUI cable to the coaxial
cable.
M bit More data bit. Setting this
bit in a DATA packet indicates
that at least one more DATA
packet is required to complete a
message of contiguous data.
MDP Modem Distribution Panel;
a distribution panel that serves
as the electrical and physical