Media Redundancy Protocol (MRP) is a data network protocol standardized by the International Electrotechnical Commission as IEC 62439-2. MRP allows rings of Ethernet switches to overcome any single failure with recovery time much faster than achievable with traditional alternatives like Spanning Tree Protocol. However, it is not able to offer zer-delay recovery time like PRP or HSR. However, it is suitable to most Industrial Ethernet applications and it is quite popular in some sectors.

400px-Mrp.svgPhoto: MRP in Ring closed-status. Credits: Biezl under CC BY 3.0

SoC-e Media Redundancy Protocol (MRP) switch IP for FPGAs supports the role of client (Media Redundancy Client – MRC) or manager (Media Redundancy Manager – MRM). These mode of operation are fully implemented on hardware, and there is no need for MRP software stack.

The MRC node performs the following functions:

  • It detects a failure or recovery of a ring port link and noti es the change by sending MRP LinkChange frames through both of its ring ports.
  • It processes the MRP TopologyChange frames and clears its FDB if requested by an MRP TopologyChange frame in a given time interval MRP Interval.
  • It forwards MRP Test frames, MRP TopologyChange frames, MRP LinkChange, MRP InTest frames, MRP InLinkChange frames, MRP InTopologyChange frames and MRP InLinkStatusPoll frames between its ring ports only.
    • The ring ports can take one of the following port states:
    • BLOCKED: all frames are dropped except the MRP frames.
    • FORWARDING: all frames are passed through according to the forwarding rules.


Photo: MRP in Ring open-status. Credits: Biezl under CC BY 3.0

The MRM node controls the ring state by performing the following functions:

  • Sending MRP Test frames at a con gured time period in both directions of the ring.
  • Setting one ring port to FORWARDING state and the other ring port to BLOCKED state if it receives its own MRP Test frames.
  • Setting both ring ports to FORWARDING state if it does not receive its own MRP Test frames on both ring ports within a con gured time according to MRP TSTdefaultT, MRP TSTshortT and MRP TSTNRmax.

The MRM indicates changes in the ring state to the MRCs by means of MRP TopologyChange frames.
The MRM does not forward MRP speci c frames (MRP Test frames, MRP TopologyChange frames, MRP LinkChange frames) between its ring ports.

SoC-e provides technology to integrate these functionalities in the following product:

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