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Cisco wlc 9800, issue AP 2802I interf radio 2.4 and 5 Ghz is disabled




I have Cisco Wlc 9800 , i add AP Cisco C9115AXE-E with success and interface 5 GHZ is enabled and
operation status is green
But in AP AIR-AP2802I-E-K9 i added in wlc but the interface radio for the both 2.4 GHZ and 5GHZ is red
see below these screenshots

how to solve the problem so that the AP 2802I must green  like the AP C9115






7 Replies 7

Flavio Miranda


 Considering that all is good on the WLC, next step you can check is if the AP is receiving the correct power from PoE, if you are using PoE, of course.

Go to the switch and look how much power the AP is receiving.

show power inline interface

show cdp nei detail

Arshad Safrulla
VIP Advocate VIP Advocate
VIP Advocate

As I can see from the screenshot you shared, you are using a POE injector. for 2802 to work you need POE+ (802.11at) capable power injector or POE+ capable switch. Below is from the Data sheet


Input power requirements

●  802.3at PoE+, Cisco Universal PoE (Cisco UPOE ®)
●  802.3at power injector (AIR-PWRINJ6=)


So please make sure that you either change the POE injector or connect the AP to an switchport with POE+ or higher capability. 

Cisco Access Point Power Requirements Quick Reference - Cisco

Arshad Safrulla


you can also check the network status for 2.4Ghz, make sure its enabled.

show ap dot11 24ghz network

for 9100 it surely seems like POE issue



-hope this helps-

Thanks for your reponse @ammahend @Arshad Safrulla @Flavio Miranda 

According to the log at the AP level and Switch cisco 3560
the problem is at the switch level (poe problem) you have to change the switch so that the AP will be functional and activate the 5 and 2.4 GHZ radio

And suite a log is Bug   AP1562 PoE negotiation failed with CDP




Did you physically verify that the AP is directly connected to a POE capable switch? As per the screenshot it looks like it is connected to a POE injector as well.

If you are using a compatible POE injector to power an AP connecting to a POE capable switch, it is must that you disable POE in the switchport, let the POE injector power the AP. Otherwise it may create POE negotiation issues.

So from the switch "no power inline"

Arshad Safrulla

@Arshad Safrulla  yes i use compatible power injector for AP 2802I , and i disable POE in the switchport

Always the same problem : please find below log for AP Cisco 2802

May 27 13:47:57 brain: Power mode: Degraded/Reduced Power, power_detection: DC_adapter(FALSE), 802.3AF_POE(TRUE)
May 27 13:47:57 SYS-COND: SYS-COND: AP is in critical condition
May 27 13:48:00 brain: Restart POE negotiation
May 27 13:48:01 brain: CDP PoE negotiation START
May 27 13:49:01 brain: CDP PoE negotiation FAILED !!
May 27 13:49:01 brain: LLDP PoE negotiation START
May 27 13:49:33 brain: LLDP PoE negotiation FAILED !!

It's a bug Cisco is annonced, if i understand correctly you should change a switch WS-C3560-48PS


According to Cisco

Cisco Bug: CSCvs15528
AP1562 PoE negotiation failed with CDP
Last Modified
Mar 03, 2022

Products (19)
Cisco Aironet 1540 Series, Cisco Aironet 1560 Series, Cisco Aironet 1800 Series, Cisco Aironet 1810 Series OfficeExtend Access Points, Cisco Aironet 1810w Series Access Points, Cisco Aironet 1815 Series Access Points, Cisco Aironet 1830 Series Access Points, Cisco Aironet 1840 Series Access Points, Cisco Aironet 1850 Series Access Points, Cisco Aironet 2800 Series Access Points

Known Affected Release

Description (partial)
Symptom: PoE negotiation failed with CDP after a period of time from bootup, and this causes both radios down. Nov 19 14:42:03 brain: CDP PoE negotiation START Nov 19 14:43:04 brain: CDP PoE negotiation FAILED !! If PoE switch supports both CDP and DDLP, AP starts PoE negotiation with LLDP and radios come back up. However, using LLDP is not a possible workaround. After a period of time, PoE negotiation also failed with LLDP and both radios goes down. Nov 19 14:43:04 brain: LLDP PoE negotiation START Nov 19 14:43:36 brain: LLDP PoE negotiation FAILED !! Conditions: This problem is observed when AP1562 is powered by PoE.
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