Catalyst 9800-80 fail to send CAPWAP discovery response to C9120AX-B

[azeezmohammed]

Team, 
*****Urgent Issue....Need some quick feedback to troubleshoot**************
I am actively troubleshooting Catalyst 9800-80 (FW: 17.7.1) failing to send CAPWAP discovery response to C9120AX-B(FW Version: 17.8.0.102) having issue. 
Subnet both AP & WLC: 96.97.72.128/29
Same management VLAN
Steps applied on AP to discover WLC:
1. statically assigned primary WLC IP address (96.97.72.130)
2. Also DHCP Option43 configured on WLC. 
But AP is not able to join WLC and I see this error "Discovery Request sent to 255.255.255.255, discovery type UNKNOWN(0)"
I have attached different logs, show run & other info, please review & let me know the troubleshooting steps....Thanks in advance. 

[Kasun Bandara]

Did you configured DHCP correctly in AP network? AP should get IP from DHCP or you can assign static IP to AP in same ip range.

[azeezmohammed]

I have assign static IP using before command

capwap ap primary-base WLC Name WLC IP Add

[Kasun Bandara]

that is for mapping of WLC. check you have valid IP assigned to Access point via static IP config or DHCP

[Leo Laohoo]

Downgrade to either 17.3.5 or 17.6.3.

[azeezmohammed]

Do you think this is bug associated with WLC FW 17.7.1 ?

[Leo Laohoo]

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@azeezmohammed wrote:

Do you think this is bug associated with WLC FW 17.7.1 ?

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Downgrade to 17.3.5 or 17.6.3 and see if the AP joins the WLC.  
If it is, then try upgrading to 17.8.X and try again.  If the AP refuses to join the WLC, then contact TAC.

[azeezmohammed]

I will try downgrading it. 

I was checking Show wireless interface summary please uploaded image for output
Do you think the wireless interface not configured correctly?

[Leo Laohoo]

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@azeezmohammed wrote:

capwap ap primary-base WLC Name WLC IP Add

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What is the WLC's IP address?

[azeezmohammed]

96.97.72.130

[marce1000]

-  Review the 9800-80  configuration with the CLI command : show  tech wireless , have the output analyzed by  https://cway.cisco.com/tools/WirelessAnalyzer/  , please note do not use classical show tech-support (short version) , use the command denoted in green for Wireless Analyzer

 M.

[Rich R]

Check your WLC config as @marce1000 says.
Then check DHCP as @Kasun Bandara says.  You said "I have assign static IP using before command" but that command is to configure the WLC details *not* the AP interface IP.  The AP needs an IP address before it can do anything - either from DHCP or static config.
Logs showing deep green mode - see https://community.cisco.com/t5/wireless/cisco-ap-9120-in-deep-green-mode-no-ip-from-dhcp/td-p/4576897 - in that case user had forgotten to configure 802.1q on the switch port.  Basically this is telling you that the AP cannot get DHCP so solve that by checking switchport, VLAN and DHCP server config.

[azeezmohammed]

@marce1000 , @Kasun Bandara , @Rich R & @Leo Laohoo 
Do we have a CLI command to change date & time on Cisco C9120AXI-B AP?
Currently I see C9120AXI-B & Cisco 9800-80 time is mismatch. 

[Rich R]

@azeezmohammed no need to set time on AP.  That is done by the discovery response from the WLC which contains a CAPWAP time sync field like the one below from a packet capture.  Refer back to the advice given already above - sort out the basics:
Type: (t=37,l=11) Vendor Specific Payload: Cisco AP Time Sync
Type: Vendor Specific Payload (37)
Length: 11
Value: 0040960000975ee9376401
Vendor Identifier: Unknown (4232704)
Vendor Element ID: 151
Vendor Data: 5ee9376401
Cisco Element ID: AP Time Sync (151)
Cisco Value: 5ee9376401
AP TimeSync: Jun 16, 2020 22:19:32.000000000 GMT Summer Time
Type (?): 1

[azeezmohammed]

I was able to fix this issue....WLC was missing wireless management interface and once I configured that AP was able to discover the WLC.