SCALANCE X204RNA SCALANCE X204RNA EEC (PRP)
Operating Instructions, , C79000-G8976-C294-03
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Network topologies and redundancy
3
3.1
Network topology and redundancy
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 SCALANCE X-200RNA devices 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
procedure allows data communication to be maintained without interruption if there are
interruptions in the network. Other redundancy procedures have a reconfiguration time of the
network of, for example 200 ms (MRP, 50 nodes in the ring) or 300 ms (High Speed
Redundancy, 50 nodes in the ring) and can therefore not 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 family are used to connect end devices without
integrated PRP interfaces to parallel networks.
Which topologies can be implemented?
With the SCALANCE X-200RNA devices, nodes or entire network segments without PRP
capability can be connected to a "Parallel Redundancy Protocol" network.
The SCALANCE X-200RNA products with their PRP capability can be used to implement an
integrated solution for network components and protective devices for a substation and also
process application.
The SCALANCE X-200RNA can manage a maximum of 1023 MAC addresses.
Note
Make sure that the maximum permitted cable lengths for the relevant devices are not
exceeded. You will find the permitted cable lengths in the technical specifications.