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Forum Discussion
GS105PE - PoE Passthrough issue with Unifi Switch
Hi,
I have a Unifi USW-8P-60 switch powering my GS105PE which works fine. However PoE Passthrough seems to be an issue, the LED on Port 1 keeps blinking and it doesn't power my Access Point which is PoE capable. Port 5 is showing an amber LED so should be able to power a bit over 7W according to the spec sheet. The AP I'm attaching uses 3-4W.
The strange thing is that it worked when I upgraded the GS105PE to the latest firmware (v 1.5.0.4) but as soon as I had to reboot after I needed to install the new boot loader, it stopped working again.
Kind regards,
Wesley
3 Replies
Hi wesback
First, the Unifi USW-8P-60 switch can only provide 802.3af PoE from what I can see. The Netgear switch will work with being powered from either an 802.3af or 802.3at PoE source. The orange light on port 5 indicates that the Netgear switch is being powered by an 802.3af source. That makes sense as the Unifi USW-8P-60 switch provides 802.3af PoE.This is important because it affects how much PoE budget the Netgear has, in order to power it's own devices. If you look at the datasheet here:
http://www.downloads.netgear.com/files/GDC/datasheet/en/ProSAFE_Web_Managed_Switches_DS.pdf
You will see that if I power the Netgear switch with 802.3af PoE, then the switch in turn will have a 7.9W budget. And if I power the Netgear switch with 802.3at PoE, then the switch in turn will have a 19W budget.You mention that your AP only needs 3-4W power, so it seems that it would be OK. But, what many forget is that the consumed power is different than reserved power. It depends on the PoE Class of your AP. Please refer to: http://aruba.i.lithium.com/t5/image/serverpage/image-id/14578i71D290D9F50D2F8C?v=1.0
As you can see:
- If you AP is class 0, then the Netgear cannot power it as the AP would require up 13W reserved. The switch cannot do that as it only has 7.9W budget.
- If you AP is class 1, then the Netgear can power it as the AP would require up to 3.8W reserved. The switch can do that as it has 7.9W budget.
- If you AP is class 2, then the Netgear can power it as the AP would require up to 6.5W reserved. The switch can do that as it has 7.9W budget.
- If you AP is class 3, then the Netgear cannot power it as the AP would require up 13W reserved. The switch cannot do that as it only has 7.9W budget.
- If you AP is class 4, then the Netgear cannot power it as the AP would require up 25W reserved. The switch cannot do that as it only has 7.9W budget.What matters is how much power devices reserves, based on their PoE class. What class is your AP? I have never seen an AP that is not either class 0, 3 or class 4 (none of which the Netgear can power with your setup), so I would be surprised if you AP was something different.
Cheers- Thanks for the great explanation. Can't seem to find the class immediately but I'm guessing it is probably 4 looking at the other models. A day where you learn something is a good day đ
What's strange though is that is worked for a while.Hi again,
I can't really understand how it could have worked beforehand, if it did. It doesn't make sense - especially if it is a class 4 access point, which many APs are these days with wireless AC :) On some switches, you can limit the amount of power a device is allowed to receive and thus limit the reserved power budget to a given device. I am fairly certain the Netgear PLUS switches (such as the GS105PE) cannot do this.
It is actually fairly common that support get questions on this particular switch, so we know your situation well. There is not much you can about it, unfortunately.
Cheers
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