It is a pity that neither Carambola nor Carambola2 expose a RMII or MII interface. This means when attaching on the boad to another device like an ethernet switch, we would normally need ethernet magnetics in the signal path.

There are several application notes of various vendors about using capacitive coupling of two 100-base-tx PHY's, like:
http://www.ti.com/lit/pdf/snla088 (TI)
http://www.micrel.com/_PDF/Ethernet/app ... an-120.pdf (Micrel)

you can even find more from Intel and others.

Did anyone yet attach the Carambola2 via capacitive coupling to another ethernet PHY on the same board? If yes, using what particular connection / capacitors ?

Thanks in advance!

i have connected Carambola 1 directly without magnetics on an ethernet device
below drawing
works fine