Wireless Access

Occasional Contributor I

303H, POE+, actual usage vs required allocation

I'm deploying 303H AP's in several applications that will require a phone to sit behind the AP and be powered off of the AP.  the total draw of the AP and the phone when both are up is about 6W total, well below the max draw of the AP.  I have two problems :

1. Unless I allocate 21W or more on the port level of the equipment that I'm using to power the AP, the 303H disables POE on ethernet 3, even though the AP only draws 4w by itself and 5.9W with the phone powered off of the port.  I've tried enabling IPM, I've tried disabling LLDP MED on the delivering equipment, I've tried all sorts of config changes but none of them give the desired affect.  The AP never actually draws more than 5.9W but it disables all PoE functions unless it gets a signal from the equipment that it has a full 21W available.  Unfortunately, the device that is powering the AP (zhones CPE 2625P) does not allow over subscription of PoE power for the device.  So, I have to allocate 21W per port to make this work but I only have 64W total to allocate so the 4th port doesn't have enough power to make it work. I have a work around for the 2625p unit.  My other CPE though is a 2608T which is an 8-port cpe.  this has a total power allocation of 124W and I can't fool the device into thinking it has more (max power supply is 150w for these which is my workaround for the 4 port units).  Any ideas on how to make these AP's allow PoE on ethernet 3 even though they won't have a full 21 W available to them (they don't need it)?

2. I'm trying to get the phones to switch VLANs to a voice vlan when plugged into ethernet 3.  I've enabled LLDP on that port and assigned the voice vlan to it.  It gets ignored.  This works fine off of the CPE devices but not off of the 303H port directly.  I know on my HP switches, I have to define the mac address mask so that the switch knows to switch the phones to the right tagged vlan when it sees them but I don't see any option on the aruba controller 7210 running to do that.  I know the vlan is active on the AP because if I present the voice vlan untagged on the port, the phones gets an IP in the right vlan and works fine.  I don't want to do that though because I want to present the guest internet vlan on the phones data port and if the guest unplugs the phone they will come up on the correct vlan.


I've been going in circles on this one for a few days.  I've got potential workarounds, but none of them are very clean and I'd like to avoide them if possible.


thanks for any suggestions.





Re: 303H, POE+, actual usage vs required allocation

Concerning your first issue:

Do you have the ap-poe-power-optimization provisioning option enabled for this AP? That will reduce the amount of power the AP claims via LLDP, but will disable both USB and PSE. USB can be overruled, but PSE will always be off in this case.

If you did not enable this option (default), enabling PSE still requires the AP itself to be powered by DC or an 802.3at compliant (class 4) POE source.

While it is true that the typical consumption of an AP-303H is much lower (worst case idle power consumption is <5W), the power budget needs to be based on worst-case consumption in fully active mode, which is 9.7W.

In addition, when we enable PSE, that could result in a maximum of 15.4W being drawn from the ethernet power. As a result, we need the full 25.5W 802.3at POE budget to enable this capability.

I'm actually not sure by you claim to "only" need 21W for this. At the switch side, max 802.3at budget would translate to 30W.

Occasional Contributor I

Re: 303H, POE+, actual usage vs required allocation

If I set power on the switch port to anything 21w or over, PSE is enabled. In this configuration, total draw at the port is 5.9w for the AP and the Phone. There will never be anything more attached to these APs.

What is the point of IPM? It would appear to exist to allow for flexible allocation of power? Also, in another application, limiting power at the switch port does work; using an aruba 24 port Poe+ switch with power limited to 15w and the AP successfully powers the Phone. In this scenario, the AP draws the full 15w allocation.

So this appears to be contradictory to requiring nearly 30 watts to allow the pse port to work. In neither of my use cases does that hold true.

Thanks for the reply and I’d love to discuss further to see if there is a solution to my issue.


Sent from my iPhone

Re: 303H, POE+, actual usage vs required allocation

The AP simply attempts to secure the absolute power budget it may need. If the POE negotiation with the switch is successful, the AP will operate without restrictions. Whether or not the switch really reserves this amount of power and has it available is not something the AP "is aware of", unless the exceptional situation occurs that the AP will actually need the full budget, which may then cause the AP to power cycle.

The PSE feature was explicitly excluded from the IPM scope, since it can represent such a large additional power load (up to 15.4W) relative to the total power consumption of the AP. There are no AP features that IPM can disable that would compensate for somebody attaching a full load on the PSE port.

New Contributor

Re: 303H, POE+, actual usage vs required allocation

Regarding your second issue where Phone doesnt fall on to the correct vlan, Do you have LLDP MED enabled for those ports?




If LLDP MED is configured on both AP and the phone, it should recieve the appropriate VLAN


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