Siemens SCALANCE X-200 - Page 21

Network topologies / media redundancy
2.1 Network topologies
SCALANCE X-200
Operating Instructions, 12/2011, A5E00349864-19
21
Figure 2-7 Ring topology with optical ring, example with SCALANCE X202-2IRT
To increase availability, optical or electrical bus topologies made up of X-200 IE Switches
with an IE Switch X-200, IE Switch X-300, SCALANCE X414-3E, OSM version 2 or ESM
version 2 configured as a redundancy manager can be closed to form a ring. The
IE Switches X-200 are first connected over their ring ports to form a bus. The two ends of the
bus are closed to form a ring by a switch operating in the redundancy manager mode.
Devices of the IE switches X-200, X-300, X-400 product families, or OSMs / ESMs can be
used as the redundancy manager. When a switch is used as the redundancy manager, the
ring ports are isolated from each other if the network is operating problem-free.
The IE Switch X-200, IE Switch X-300, SCALANCE X414-3E, or OSM / ESM operating in the
redundancy manager mode monitors the connected bus over its ring ports and switches the
ring ports through if there is an interruption on the connected bus; in other words, it restores
a functioning bus over this substitute path. Reconfiguration takes place within 0.3 seconds.
As soon as the problem has been eliminated, the original topology is restored; in other
words, the ring ports in the redundancy manager are once again disconnected from each
other.