Chapter 1. Introduction
GFK-2892F
March 2019
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Media Redundancy Protocol Support
PROFINET Media Redundancy Protocol (MRP) supports devices configured in a ring topology. MRP is specified
as part of IEC62439 and has been adopted by the PROFINET specification, which provides for convenient
configuration of the ring topology and necessary parameters. Like PROFINET IO data, Media Redundancy
Protocol operations are not routable between different IP subnets.
Each device within an MRP ring has two physical pathways to the IO-Controller. To connect to the ring, each
device requires an integrated switch with at least two external ports (ring ports) that support MRP. Devices
that are not MRP-capable can be connected to a device in the ring (i.e., an MRP-capable switch in the ring), but
they should not be in the ring themselves. The redundancy capability offered by the ring topology only extends
to the devices on the ring that are MRP-capable and enabled.
One of the devices on the ring must be configured as the Media Redundancy Manager (MRM), and all the other
devices must be configured as Media Redundancy Clients (MRCs). The GCG001 can be configured as an MRC.
Configuring the GCG as an MRC alters how the Ethernet ports connect to the network. They attempt to
indicate their state to the MRM before allowing traffic to flow between the ports and close the ring topology
through the internal switch. They also send out notifications to the MRM when a port is lost. Operation of the
GCG001 is otherwise unchanged.
The MRP configuration is stored in non-volatile storage in the GCG001 and activated immediately upon
powering up. Non-volatile storage is updated as part of a connection with the IO-Controller. A PROFINET
Discovery & Configuration Protocol (DCP) Reset disables MRP Client operation and updates non-volatile
storage. The current state of the MRP configuration is provided as part of the GCG’s Gateway Status Bits which
are accessible to user application logic. Refer to the description of Gateway Status Bits in Section 5.1.1 for
further details.
Fast ring-break detection is not fully functional until all MRP clients have received their MRP configuration. For
a discussion of ring-break detection and bumpless operation with MRP, refer to sections 6.1.1 and 6.1.2 in the
PACSystems RX3i & RSTi-EP PROFINET I/O Controller Manual,
GFK-2571K or later.
