What are the specifics of PoE ethernet magnetics
PoE magnetics are designed to sustain also the DC currents that flow through the magnetics. You should not use magnetics which aren't marketed as PoE magnetics. 

For example see coilcraft's

http://www.coilcraft.com/eth1-460.cfm

They're designed to comply with the IEEE PoE standard and are capable of sustaining a certain amount of wattage, in this case 60W but 13-25W magnetics are also common.

Normal magnetics may not be able to handle the DC offset currents during PoE operation.

Using 'normal' magnetics is probably asking for trouble.