What ferrite for Ethernet Phy?
It's old school good practice. If you redesign your schematic, you will see a PI filter composed by two capacitors before, two capacitors after the inductor.
It will prevent inrush high speed vdd fluctuations from the digital part of the chip, vddIO, to the analog part, vdda.
At 100mbps any small ferrite will do. Pay attention on wire geometry in this region!