Glossary
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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.
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 RJ-45 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.
PUNCH-DOWN BLOCK—The punch-down block is the wiring panel where the house
wiring from the building’s offices terminates. This is where many 10Base-T hubs would
be located. Wiring installers use a special punch-down tool to insert the UTP wire for
data and voice applications.
REPEATER—A device used to extend the length, topology, or interconnectivity of the
physical medium beyond that imposed by a single segment, up to the maximum
allowable end-to-end trunk transmission line length. Repeaters perform the basic actions
of restoring signal amplitude, waveform and timing applied to normal data and collision
signals.
RJ-45—This connector is a 10Base-T and 100Base-T standard and is used to connect
STP/UTP cabling. It is inexpensive and easy to install onto UTP cable.
Shielded Twisted Pair (STP)—Two, or more, insulated wires that are twisted
together and then wrapped in a cable with metallic braid or foil to prevent interference
and offer noise-free transmissions. Also refers to IBM Type 1 cable. c
SIGNAL QUALITY ERROR (SQE)—Also referred to as Collision or Collision
Presence. This occurs when two devices attempt to transmit at the same time, which is
an illegal condition. All ATI transceivers test for SQE.
SQE TEST—Commonly referred to as Heartbeat, is a special 802.3 signal sent by the
MAU to the DTE to test the collision detection function. Some DTE want SQE and others
do not. Repeaters do not want the SQE Test.
STANDALONE—Repeater operating as a hub on its own; i.e., not a module among other
modules in a department concentrator chassis.
STRAIGHT-THROUGH—A type of wiring connection where the pins of one connector
connect to the same pins of another connector. For example, pin 1 of one connector
connects to pin 1 of another connector.
TELCO CONNECTOR— A 50-pin receptacle that plugs into the front of the hub,
enabling cables from external devices to connect to the hub.
THICK ETHERNET—See 10Base5
