Glossary
62
MANAGED MODULE
— An intelligent repeater in a department concentrator
chassis that makes management data available to the Master.
MANAGEMENT AGENT
—Software that is used to view hub activity and set
hub variables.
MASTER
—A repeater in the topmost position in a department concentrator
chassis that contains and downloads the management agent software to Backup
and Slaves. The Master contains the only active image of the management agent
and controls the management functions of the Backup and Slaves.
MAU
—See Medium Attachment Unit
MAU-to-MAU, HUB-to-HUB WIRING
—10BASE-T MAU-to-MAU or hub-to-
hub wiring generally requires a crossover cable located somewhere along the UTP
cable run. This may commonly occur at the punch-down block or between the RJ45
wall receptacle and the workstation.
MAU/TRANSCEIVER
—An Ethernet transceiver is a MAU. A 10BASE-T
MAU interfaces the UTP media to an AUI port on a workstation, repeater, bridge
or other Ethernet device.
MDI/MDI-X
—See Medium Dependent Interface
MEDIUM ATTACHMENT UNIT (MAU)
—In a LAN, a device used in a data
station to couple the DTE to the transmission medium.
MEDIUM DEPENDENT INTERFACE (MDI)
—The mechanical and
electrical interface between a hub and a transceiver (MAU). MDI-X is another
version of the interface that enables hubs to connect using different pin-outs,
thereby avoiding conflicts that occur when receiving and transmitting packets use
the same pin-out.
MODULE
—A single repeater when it is mounted with other repeaters in an
AT-36C
x
or AT-36E
x
department concentrator chassis.
N-SERIES
—A barrel shaped, threaded connector used on 10BASE5 (thick
Ethernet) coaxial cable.
PATCH PANEL
—A 10BASE-T patch panel may be used between a punch-down
block and UTP workstation. The patch panel generally has a female RJ45
connector on the front for each workstation and a Telco (RJ21) connector on the
back, which is wired to a punch-down block. This provides a convenient way for the
installer or network manager to connect the hub 10BASE-T ports into the desired
building locations.
POLARITY CORRECTION
—Many 10BASE-T UTP ports have a polarity
correction function. If the UTP wiring has RD- and RD+ inadvertently crossed,
the polarity correction function will sample the signal and electrically swap the
wires. If the TD- and TD+ wires are crossed, the correction would occur at the
MAU on the other end of the UTP link. This occurs within a single pair and should
not be confused with the crossover cable.
PROPAGATION DELAY
—The time it takes a signal to travel from the input of
a system component to the output. Usually measured in nanoseconds. IEEE 802.3
has specific propagation delay maxima for computing propagation budgets when
designing a LAN. Cable length plays a major role in propagation delay; for
example, a 50-meter (164-foot) AUI cable has a maximum allowable propagation
delay of 257 ns. The propagation delay of cable depends on the length and velocity
factor of the cable type. There are also propagation delays associated with
electronics attached to the system.
