I would recommend putting your public ethernet card in the main rack. This will make connection to the processor simpler if you connect from public. I have a similar setup in our plant and it held me up for a bit when I tried to connect from my desk. Whenever someone new in our organization tries to connect, we have to set up RSLinx to use the private network ethernet cards to bridge the public to the main rack. It can be done the way you show, it is just a simpler connection to the processor if you move the public card to the main rack.