AT-30xxTR Multiport Repeaters
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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-ft.) 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.
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.
RJ45
—This connector is a 10BASE-T standard for connecting UTP cabling. It is
inexpensive and easy to install onto UTP cable.
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.
SIMPLE NETWORK MANAGEMENT PROTOCOL (SNMP)
— SNMP is a
TCP/IP protocol that generally uses the User Datagram Protocol (UDP) to
exchange messages between a management information base and a management
client residing on a network. Since SNMP does not rely on the underlying
communication protocols, it can be made available over other protocols, such as
XNS or DECnet.
SLAVE
— A repeater that behaves as a “dumb” module managed by a Master in
a department concentrator chassis. Slaves operating standalone perform only
simple regeneration and retiming tasks associated with repeating and are not
manageable.
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.
