Add Ethernet Switch chip to project based on PIC18F97J60
You don't necessarily need a switch. If there are no many devices on your network and the amount of data is small, the hub might be enough. You would need to handle collisions in software e.g. by resending the data after random delay. 

Here's an example of a simple hub: http://www.zen22142.zen.co.uk/Circuits/Interface/pethhub.htm. You did not mention the PoE mode you are using, but with this solution, mode B (power on non-data pairs) is easy to implement.