User manual

CentreCOM AT-3675 SNMP-Managable Learning Bridge
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MODULE—A single repeater when it is mounted with other repeaters in an
AT-36Cx or AT-36Ex department contentrator chassis.
N-SERIES—A barrel shaped, threaded connector used on 10BASE5 (thick
Ethernet) coaxial cable.
PATCH PANEL—A 10BASE-T patch panel may be between a punch-down
block and UTP workstation. The patch panel generally has a female RJ45
connector on the front for each workstation and a Telco (RJ21) connector on
the back, which are wired to a punch-down block. This provides a convenient
way for the installer or network manager to connect the hub 10BASE-T ports
into the desired building locations.
PHYSICAL MEDIUM ATTACHMENT (PMA)—The portion of the MAU
that contains the functional circuitry.
PHYSICAL SIGNALING (PLS)—That portion of the physical layer
contained within the DTE that provides the logical and functional coupling
between MAU and data link layers.
POLARITY CORRECTION—Many 10BASE-T UTP ports have a Polarity
Correction function. If the UTP wiring has RD- and RD+ inadvertently
crossed, the polarity correction function will sample the signal and electrically
swap the wires. If the TD- and TD+ wires are crossed, the correction would
occur at the MAU on the other end of the UTP link. This occurs within a
single pair and should not be confused with the cross-over cable.
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 maximums for computing
propagation budgets when designing a LAN. Cable length plays a major role
in propagation delay. [i.e, a 50 meters (164 ft.) AUI cable has a maximum
allowable propagation delay of 257 ns.] The propagation delay of cable is
dependent on 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,
wave form and timing applied to normal data and collision signals. In the
manual, “repeater” refers to a standalone unit or a module in an AT-36Cx or
AT-36Ex department concentrator chassis. For the purposes of network
topology analysis, either a standalone repeater or a fully populated
department concentrator counts as just one repeater.
RJ45—This connector is a 10BASE-T standard for connecting UTP cabling.
They are 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.