I designed an ethernet circuit, and I am trying to lay it out on the board. The app notes and data sheets specify that the ethernet ground be isolated from the system ground and to be connected through a 0 ohm resistor. There are to be no ground or power planes underneath the magnetics and RJ45 connector too. . so where would my ethernet ground be if i can't have a ground plane under the connector/magnetics? My particular IC/magnetic/connector companies provide no specific guidelines on pcb layout, but there is obviously some very important rules to follow that I can't find. I have been looking on other boards I can find, and there seems to be a very specific pattern on layout, however I can't see the internal layers, so I'm a little in the dark. It looks like a keep out zone around these components, and I have done some reading around and see trace lengths and widths on the differential Rx and Tx lines being stated specifically for other ethernet app notes, but nothing that I can go back to and say 100% that it applies to my design. Does anyone know if there is a standard that requires specific layout guidelines for 10BASE-T ethernet circuitry? I don't want to make up my own rules for layout if it has a standardized layout strategy. I hope someone here has done an ethernet layout and can point me in the right direction please.