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FL SWITCH MM HS(Rapid) Spanning Tree
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PHOENIX CONTACT
5-1
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FL SWITCH MM HS(Rapid) Spanning Tree
5.1
General function
Loops
The Rapid/Spanning Tree Protocol (RSTP) is a standardized method
(IEEE 802.802.1w/IEEE 802.1d) that enables the use of Ethernet networks with redundant
data paths. Ethernet networks with redundant data paths form a meshed topology with
impermissible loops. Due to these loops, data packets can circulate endlessly within the
network and can also be duplicated. As a consequence, the network is usually overloaded
due to circulating data packets and thus communication is interrupted. The meshed
structure is thus replaced by a logical, deterministic path with a tree structure without loops
using the Spanning Tree algorithm. In the event of data path failure, some of the previously
disconnected connections are reconnected to ensure uninterrupted network operation.
IEEE 802.1w
The Rapid Reconfiguration Spanning Tree Protocol (RSTP) is a standardized method (IEEE
802.1w) that enables the use of Ethernet networks with redundant data paths and prevents
the long timer-controlled switch-over times of STP. Usually, the formal term "Rapid
Reconfiguration Spanning Tree" is not used, rather just "Rapid Spanning Tree Protocol
((R)STP)" .
Example:
In the following network topology (six) redundant paths have been created to ensure access
to all network devices in the event of a data path failure. These redundant paths are
impermissible loops. The Spanning Tree Protocol automatically converts this topology into
a tree by disconnecting selected ports. In this context, one of the switches is assigned the
role of the root of the tree. From this root, all other switches can be accessed via a single
data path.
Figure 5-1
Possible tree structure with Spanning Tree
When operating MRP (Media Redundancy Protocol) make sure that (R)STP is disabled
on the ports that are configured as MRP ring ports.
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740051
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WITCH MC
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2 70 0
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