Hub or switch in cabinet

I am going to install a profinet CPU and a TP277. The panel will be connected to the plc by a FTP ethernet cable. The plc is connected to the factory network. Do I install a hub or a switch in the cabinet, and can I use a commercial product like 'D-Link' or an industrial product from Siemens (Scalance)?
Does someone know if I can route from the MPI-port on my TP277 to the plc on ethernet (no mpi cable between TP277 and PLC). And can I route from that mpi-port on the TP277 over the ethernet to TP177A on mpi (mpi on plc only to TP177A not to TP277)?
Thanks

Do I install a hub or a switch in the cabinet

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Principally, it is almost always better to use a switch. The advantages outweigh the small price difference between the two.

can I use a commercial product

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We have used commercial products as well as indicstrial products extensively. I have seen no noticeable performance difference. The major advantage of an industrial product is from an EMC perspective and possibly also voltage tolerance. But a commercial product supplied from a UPS source and installed in a well designed cabinet serves the purpose quite well. The other thing to remember about the commercial products is that many of the small units use a voltage adapter that plugs into a wall socket. Avoid those like the plague.

The smallest PN CPU is a 315-2PNDP which costs approx 1900 Euro. And the TP277 cost approx 1600. So the cost of one of the smallest Siemens Scalance unmanaged swithces (approx 140 Euro) is really neglible in such a project.

You cannot route like this:
PC-(ethernet)-PLC-(MPI)-TP177A

You can route like this:
PC-(MPI)-PLC-(ethernet)-PLC-(MPI)-TP177A