Specifications

Glossary
SCALANCE X-400 BA
Operating Instructions, 03/2009, C79000-G8976-C186-07
153
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.
Redundancy manager (RM)
Switch in a ring topology that does not forward any frames between its ring ports if there are
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 and
so restores an intact connection between all switches.
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
SB
Standby function.
Segment
In the Ethernet bus system, transceivers connected together 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 a segment.
Signaling contact
Floating relay contact via which the detected error states can be signaled.
Single mode
In single mode transmission, (and monomode transmission) the pulse is transmitted by a
straight mode (wave). Attenuation is mainly caused by physical absorption and dispersion as
well as by mechanical bending. The amount of attenuation depends, among other things, on