AT-4016F Installation Manual
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HUB/REPEATER—A hub is a central signal distributor. It is used in a wiring topology
consisting of several point-to-point segments originating from a central point. The term
hub is often used interchangeably with the term repeater. Multiport 10Base-T, 10Base2
and fiber optic (10Base-FL, FOIRL) repeaters are considered hubs. See Repeater.
HUB-to-HUB WIRING—See MAU-to-MAU Wiring
HUB-to-MAU WIRING—UTP cables for 10Base-T hub-to-MAU or NIC cards are wired
straight-through. An RJ-45 receptacle at the hub would wire pin-to-pin to the RJ-45
receptacle at the MAU.
IMPEDANCE—An electrical characteristic of a circuit dealing with the combination of
the AC and DC resistance and the appearance of that resistance to attached circuits.
INTERIM LAYER MANAGEMENT INTERFACE (ILMI)—Protocol defined by the
ATM Forum UNI standards for managing the UNI.
JABBER LOCK-UP—The MAU’s ability to automatically inhibit the transmit data
from reaching the medium if the transmit data time exceeds a specified duration. This
duration is in the range of 20 ms to 150 ms. Jabber lock-up protects the medium from
being overrun with data packets from a possibly defective device.
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
LAN EMULATION—Methodology for mimicking the appearance of a LAN by
rendering the ATM switching fabric invisible to the user; enables user interface
software to treat a virtual LAN as if it were a physical LAN.
LAN EMULATION CLIENT (LEC)—ATM Forum-defined specifications in support of
LAN-to-LAN connectivity, called LAN Emulation. LEC defines that set of functions
implemented in a LAN DTE to interface with an ATM network in support of LAN
Emulation.
LAN EMULATION SERVER (LES)—LES defines that set of functions implemented
in an ATM network in support of LAN-to-LAN connection establishment.
LAN EMULATION CONFIGURATION SERVER (LECS)—LECS defines that set of
functions implemented in an ATM network that provide LAN DTEs with information
regarding the location of the other LAN Emulation services.
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
