Allied Telesis AT-TS24TR - Manual (Page 85)

TurboStack Hubs with Management
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PROPAGATION DELAY—The time required for a signal to travel from the
input of a system component to the output. Usually measured in nanoseconds.
IEEE 802.3 stipulates specific propagation delay maximums for computing
propagation budgets when you design 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.
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 interface with the same pins of another connector. For example, pin
1 of one connector connects to pin 1 of another connector.
SUBSCRIBER CHANNEL (SC) CONNECTOR—A type of port connection
where the pins connect through a square push-pull mating interface.
SUB MINATURE ASSEMBLY (SMA) CONNECTOR—A type of port
connection where the pins connect through a threaded attachment interface.
(Also referred to as an SM Connector.)
STRAIGHT TIP (ST) CONNECTOR—A type of port connection where the
pins connect through a bayonet-style interface.