3700 Transmitting Low Power on the 2.4Ghz Range

[John Lee]

Hello;

I am having problems getting the 3700 APs to transmit on full power, I have 22 registered with my WLC and around half are displayed the message:

"Due to low PoE radio is transmitting at degraded power" and are only transmitting on Power Level 6, where as others are transmitting at a higher rate.

All switchports have been configured to allow the maximum power allowed.

This is only occuring on the 2.4Ghz range and not the 5Ghz.

Any ideas? I am running software version 7.6.120.

Thanks;

John

[Scott Fella]

If your AP is negotiating power at FULL, then PoE isn't the issue.  So I'm assuming your issue is that the TX power is showing a certain level or that your not getting the coverage you were expecting?  Can you provide more detail as to what issues you are seeing.

-Scott

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[Todd S]

I have 2702 APs are showing the message "Due to low PoE radio is transmitting at degraded power."  

The switches these APs are connected to are Avaya 4850+PWR which are 802.3af/at compliant.  The AP is showing the PoE status as PoE/Medium Power 15.4 w but the switch is reporting 6 - 8 w.  I'm wondering if I'm running into an LLDP issue between the AP and the Avaya switch where the AP isn't negotiating the correct amount of power it should be pulling.

[Scott Fella]

You are... The AP's negotiate using CDP and I know with some switches and LLDP you end up not negotiating properly.  You either have to set the power on the switch or you can set the AP PoE settings also:

When powered with a non-Cisco standard PoE switch, the access point operates under 15.4 Watts. Even if the non-Cisco switch or midspan device is capable of providing higher power, the access point does not operate in enhanced PoE mode.

http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_01111111.html

-Scott

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[Todd S]

Unfortunately not matter what changes are made to the AP PoE configuration or to the switch configuration, the AP isn't drawing the correct amount of power.

I did find this bug ID:
CSCup72151

Someone was experiencing the same issue but with a 3602 with the 802.11ac module.  The "fix" was to install Cisco power injectors or a Cisco switch.  Neither of those are an option for a school district with thousands of Cisco APs.

So just to confirm what you are saying, it almost sounds like CDP is required to correctly negotiate power for Cisco APs.  LLDP doesn't work that well depending on the switches you might be using?

[diego.borda]

Did you finally fix it? This worked for me.

Make sure your injector or PoE switch is PoE+ capable.

Then you must enable CDP or LLDP so AP can negotiate power.

And finally you may need to power the AP off and then back on, it will force a new PoE negotiation.