Siemens RX1500 User Manual page 732

Chapter 5
Setup and Configuration
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Figure 818: Example - Ring Backbone Configuration
To design a ring backbone configuration with RSTP, do the following:
1. Select the design parameters for the network.
What are the requirements for robustness and network fail-over/recovery times? Typically, ring backbones
are chosen to provide cost effective but robust network designs.
2. Identify required legacy support and ports with half-duplex/shared media restrictions.
These bridges should not be used if network fail-over/recovery times are to be minimized.
3. Identify edge ports.
Ports that connect to host computers, IEDs and controllers may be set to edge ports in order to guarantee
rapid transitioning to forwarding as well as to reduce the number of topology change notifications in the
network.
Choose the root bridge.
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The root bridge can be selected to equalize either the number of bridges, number of stations or amount of
traffic on either of its legs. It is important to realize that the ring will always be broken in one spot and that
traffic always flows through the root.
5. Assign bridge priorities to the ring.
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RSTP in Ring Backbone Configurations
RUGGEDCOM ROX II
User Guide
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