Hi,
I’ve just bought a RB750G and was impatient to test the POE feature. So I’ve plugged the eth1 on a POE switch … but nothing happen ?
I’ve unmounted the board and I’ve notice a 2 pins connectors not far away from the power regulation …
Is there anything special to do to have the POE working or it is a special feature ?
Yves
PoE switch is probably not compatible. RB750 only supports passive PoE (not Power over Datalines), so you need a PoE injector. http://www.routerboard.com/index.php?showProduct=86
the RB750G is not compatible with IEEE 802.3af power-over-ethernet – it’s stated in the data sheet.
one difference is that the RB750G accepts a maximum voltage 28V, while 802.3af typically feeds 48V to a device (the range goes up to 57.0V).
the power regularor on the RB750G (Cheertech RT9206) has an overvoltage protection circuit – it will shut down when the voltage is too high.
I had a RB750G which was powered through the external mains power supply, but unfortunately ended up also being connected to a POE switch. the switch seemingly detected a 802.3af compatible device attached to it, enabled the 48V power, and as a result the RB750G shut down due to overvoltage from POE, even though it was intended to be fed from the external power supply. once the ethernet cable was disconnected, the RB750G started up…
ymartin asked about the RB750G, which has gigabit ethernet ports – there are no unused lines with gigabit ethernet. power is delivered as a phantom-feed over data pins 4/5 and 7/8.
unless you use the port at 100Mbps only.
i think the mikrotik solution is a good balance between low cost and at all being able to do some sort of POE. switching regulators that can sustain 48V are expensive.
as long as you use a power injector that is not really looking for 802.3af compliant devices, it will work well.
and if you must connect the RB750G to a POE switch, don’t use port 1 as POE might shut down your router.
andy
Thanks for this explanations, it was a little bit what I expected reading different documentation.
So I think this ‘passive’ POE is not very useful if it do not follow the most used standard in the market… Manufacturer have tendency to multiply standards which are not to simplify users life 
i assume the “passive” term in mikrotik language refers to mikrotik-POE not using any POE negotiation like 802.3af does.
the idea behind 802.3af negotiation is to prevent incompatible devices from being powered with 48V.
but that is exactly what happens with mikrotik-POE. it’s too close to 802.3af but then again not compatible with it.