AT-MR415T and AT-MR815T Installation Guide
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JAM—This is a term used to describe the collision reinforcement signal
output by the repeater to all ports. The jam signal consists of 96 bits of
alternating 1s and 0s. The purpose is to extend a collision sufficiently so that
all devices cease transmitting.
JITTER—The fluctuation of the data packet in respect to a standard clock
cycle. Jitter is undesirable and must be minimized.
LAN—See Local Area Network
LINK SEGMENT—The link segment of coaxial cable is a segment that has
no MAU devices, but links together two LAN devices such as repeaters.
LINK TEST—In 10Base-T Ethernet there is a link test function that
validates the UTP link. This consists of a pulse transmitted from point A on
one pair that is validated at point B. Point B also transmits a pulse on the
second pair to be validated by point A. These pulses occur during media idle
states (in between packets).
LOCAL AREA NETWORK (LAN)—A type of limited-area broadcast
network in which devices attached to a common transmission medium.
MEDIA ACCESS CONTROL (MAC)—IEEE specifications for the lower half
of the data link layer (layer 2) that defines topology-dependent access control
protocols for IEEE LAN specifications.
MANAGEMENT AGENT—Software that is used to view system activity and
set system variables.
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 RJ-45 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 the trunk cable medium and the MAU. MDI-X is
another version of the interface that enables like devices to connect using
different pin-outs, thereby avoiding conflicts that occur when receiving and
transmitting packets use the same pin-out.
