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Network topologies and redundancy
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4.1 PRP
Parallel Redundancy Protocol
The "Parallel Redundancy Protocol" is a redundancy protocol for Ethernet networks. It is defined
in Part 3 of the IEC 62439 standard. The devices of the SCALANCE X-200RNA product line
support the PRP method. The areas of application of PRP are distributed real-time applications
with high reliability demands that depend on the high availability of the network. Compared
with classic fault-tolerant networks, PRP provides bumpless redundancy. This redundancy
method allows data communication to be maintained without interruption/reconfiguration
time if there are interruptions in the network. Other redundancy methods have a network
reconfiguration time of, for example 200 ms (MRP, 50 nodes in the ring) or 300 ms (High Speed
Redundancy, 50 nodes in the ring) and cannot therefore be used for substation applications or
other applications that require high network availability.
The PRP method has the advantage that it uses parallel, separate networks made up of standard
network components. The end devices that use this method are connected to the two networks
via a preceding device or via two integrated device interfaces. This means that the frame of the
end device can be transferred at the same time via both networks. If a transmission path is
interrupted, the frame arrives at its destination via the second path.
The devices of the SCALANCE X-200RNA product line are used to connect end devices without
integrated PRP interfaces to parallel networks.
Note
SCALANCE X204RNA EEC (PRP/HSR)
If you initialize the device as a PRP device, it behaves in exactly the same way as the SCALANCE
X204RNA EEC (PRP).
Which topologies can be implemented?
With the devices of the SCALANCE X-200RNA (PRP) product line, nodes or entire network
segments without PRP capability can be connected to a "Parallel Redundancy Protocol" network.
The products with PRP capability of the SCALANCE X-200RNA product line can be used to
implement an integrated solution for network components and protective devices for a
substation and also process application.
SCALANCE X-200RNA
Operating Instructions, 04/2022, C79000-G8976-C342-07
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