IEC 62439-2

Media Redundancy Protocol (MRP)

One of the main issues related to the benefits of IEC 61850 is its ability to work on different communications architectures while providing a high level of reliability required by the criticality of the different protection, automation and control applications.
The selection of the most efficient protocol for a specific application is based on the specifics of the protocols and the requirements of the applications, while at the same time considering costs and potential drawbacks.
After the Rapid Spanning Tree Protocol (RSTP) was considered at the initial phases of implementation of IEC 61850 based systems, it was later replaced by the Parallel Redundancy Protocol (PRP) and theHigh-availability Seamless Redundancy (HSR) protocol. This was due to the fact that they publish duplicate messages and as a result do not require reconfiguration and the associated time delay in case of a failure of a communications link.

Both the PRP and the HSR protocols are a part of the IEC 62439 standard which was published in 2012. However another protocol, Media Redundancy Protocol (MRP) is also a part of this standard and may be considered for some applications after analysis of its capabilities.
This ring redundancy protocol was developed by Hirschmann and Siemens and was first presented in 1999. It uses the basic principles of the HiPER ring and can be integrated into the IEDs, so that no additional switches are needed.

Meshed networks are not supported, which makes MRP both simple and deterministic.
The ring includes a ring Media Redundancy Manager (MRM) and Media Redundancy Clients (MRCs).
MRP may guarantee a worst-case recovery time of down to 30 ms in rings composed of up to 50 switches, and of 10 ms in rings composed of up to 14 switches.

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