AT-4016F Installation Manual
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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-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.
RJ-45—This connector is a 10Base-T standard for connecting UTP cabling. It is
inexpensive and easy to install onto UTP cable.
SDH—See Synchronous Optical Network
SIGNAL QUALITY ERROR (SQE) TEST—Signal indicates SQE function is active.
The SQE message is sent by the MAU to the DTE in the presence of a collision.
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.
SINGLE MODE FIBER—Type of fiber optic cable that uses wave propagation within
a homogenous medium to transmit signal over long-range distances (5 to 10 km).
Requires high-intensity laser light source (Class 1 emission).
SONET—See Synchronous Optical Network.
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.
STRAIGHT TIP (ST) CONNECTOR—A type of port connection where the pins
connect through a bayonet-style interface.
SUBSCRIBER CHANNEL (SC) CONNECTOR—A type of port connection where the
pins connect through a push-pull mating interface.
SUB MINIATURE ASSEMBLY (SMA) CONNECTOR —A type of port connection
where the pins connect through a threaded attachment interface. Also referred to as an
SM Connector.
SWITCH, ETHERNET—A type of Ethernet hub that filters traffic based on low-level
address. As over against a repeater, a switch does not necessarily broadcast, retime or
retransmit packets, depending on its configuration. A switch cuts down on traffic by
placing packets only on the receiver’s segment when known.
