Glossary
SCALANCE X-300
286 Operating Instructions, 10/2010, A5E01113043-10
OSM
Optical Switching Module – SIMATIC NET Ethernet switch with optical ports
Rack device (R)
A rack device (R) is intended for installation in a 19" cabinet. A rack device with (M) added to
the name is also a → modular device (M).
Rapid Spanning Tree
The Rapid Spanning Tree protocol (RSTP) allows redundant transmission paths. This
prevents circulating frames and, if a fault develops, provides an alternative path within
seconds (reconfiguration time).
Reconfiguration time
The time required to restore a functional configuration if a device fails or a network cable is
interrupted.
Redundancy client
Device in a ring topology that reacts to the test and reconfiguration frames of the
►redundancy manager.
Redundancy domain
Group of devices that support the "media redundancy" function in a ring topology. All devices
in a ring topology with media redundancy must belong to the same redundancy domain.
Redundancy manager
Device in a ring network section with ►media redundancy that monitors the ring topology.
Only one of the two ►ring ports of the redundancy manager forwards data frames when the
ring is closed.
If the ring is interrupted, the redundancy manager triggers a reconfiguration of the network
by forwarding data frames via both ring ports. This means that all remaining devices can be
reached again (►redundancy clients) in the ring over a linear bus.
Ring port
Port of a device that establishes the connection to a neighboring device in a ring topology. A
device has two ring ports.
RM
→
Redundancy manager
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