Ethernet PHY/MAC/SWITCH IC available?
There are switch IC's that use external phys (you need to have a separate MII interface that goes to a phy), switch IC's that have internal phys (the differential pairs run right into the IC), and switch IC's that do both internal and external.

A good example of this is the KSZ8873MLL/FLL/RLL 

Depending on the IC you buy the Phys can be external or internal.