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Redundancy Manager (RM)
Switch in a ring topology which does not forward frames between its ring ports in case of
functioning connections between all other switches. As soon as a connection between two
switches is interrupted, the redundancy manager forwards frames between its ring ports to
re-establish an intact connection between all switches.
Reconfiguration Time
Time required to restore a functional configuration in case of a device failure or an
interruption of a connection line.
Repeater Rule
The repeater rule, also referred to as 5-4-3 rule, specifies that a maximum of 5 segments
with 4 repeaters may be used in an Ethernet network with shared access in a star topology
(10Base2, 10Base5, 10BaseT) and that active DTEs are only connected to 3 segments. The
active DTEs also include the repeater.
Ring Port
Two ports in a switch via which it is connected with other switches to form a ring. One switch
in the ring must be configured as redundancy manager. This switch sends test frames via
the ring ports that are forwarded by all ring ports of other switches in the ring. This ensures
that the ring does not have any interruptions.
Segment
In the Ethernet bus system, the transceivers connected over the bus cable along with the
nodes connected over patch cables form a segment. Several such segments can be
connected via repeaters. When using twisted pair and fiber-optic cables, each subsection
forms one segment.
Store and Forward
An entire frame is received, its validity checked (checksum, length etc.) and then buffered.
Invalid frames are discarded, i.e. a frame is forwarded only if it is error-free.
TP Port
Port with TP connector (RJ-45 jack)
Yellow Cable
Yellow cable is a coaxial cable of the PG 8 type with an impedance of 50 Ohm. The Ethernet
standard stipulates a yellow color – thus "yellow cable". The ends must be provided with
terminating resistors for scheduling.
Industrial Ethernet Media Converters SCALANCE X-100 Series
Commissioning Manual, 06/2006, A2B00051526A, Product Version 03
Glossary
Glossary-3
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