Why is "Port Mirroring" necessary?
PROFINET is a complex communication protocol. In some situations it may be necessary to read and interpret the frame traffic with a protocol analyzer.
In order to be able to read in an Ethernet network, because expensive coupling hardware is used, which is looped into the line or is configured or a free port is configured in a switch as a "mirror port". The mirror port transmits all frames of another port of the switch as a copy. A device or PC can then run on the mirror port with the corresponding analysis software.