Siemens S7-300 Configuration Manual page 73

Topology
The following schematic shows a possible topology for devices in a ring with MRP.
Figure 3-2
The following rules apply to a ring topology with media redundancy using MRP:
● All the devices connected within the ring topology are members of the same redundancy
● One device in the ring is acting as redundancy manager.
● All other devices in the ring are redundancy clients.
Non MRP-compliant devices can be connected to the ring via a SCALANCE X switch or via
a PC with a CP 1616.
Prioritized startup
If you configure MRP in a ring, you cannot use the "prioritized startup" function in PROFINET
applications on the devices involved.
If you want to use the "prioritized startup" function, then disable MRP in the configuration.
In the STEP 7 configuration, set the role to "Not a node in the ring".
Configuring and commissioning S7 CPs for Industrial Ethernet
Configuration Manual, 09/2013, C79000-G8976-C182-13
Example of a ring topology with the MRP media redundancy protocol
domain.
Configuring the Ethernet CP with STEP 7
3.5 Media redundancy
73