Windows DHCP option 43 not working

[tachyon05]

Access Point keeps registering to the wrong WLC, ignoring the WLC I specified in option 43.  I confirmed the HEX value is correctly entered on the DHCP server using multiple generators.  Any suggestions?

[MHM Cisco World]

What is wlc platform you have?

[Flavio Miranda]

Hi @tachyon05 

 It may depend on the DHCP server. The option 43 does not work the same way in all vendor. The other option you have is add the WLC on the AP manually by using the command

capwap ap {primary-base | secondary-base | tertiary-base}controller-name controller-ip-address

You can also add the WLC you want on the Internal DNS. AP always try to resolve the URL CISCO-CAPWAP-CONTROLLER

[tachyon05]

I have 9800 WLC, and it looks like putting "00" in front of the HEX value doesn't make any difference.

[MHM Cisco World]

Can I know hex you use as op43?

[MHM Cisco World]

Still waiting 

[tachyon05]

I used these 2 generators to produce the HEX value, and they produce the same result.  I tried with and without the leading 00 since some people said leading 00 are needed for Windows DHCP.  I also set the AP to factory default using the WLC GUI, but the AP still registers with the wrong WLC.

https://lihaifeng.net/option43/#/

https://shimi.net/services/opt43/

[MHM Cisco World]

What is hex and what tlv you use in dhcp server ?

[MHM Cisco World]

If you select correct tlv (043) and use correct hex for IP' then last thing prevent ap from choosing wlc in dhcp it have IP of old wlc which have priority than new one learn via dhcp.

[Leo Laohoo]

What is the HEX value?

[MHM Cisco World]

Take a  seat' lol...

@tachyon05  just to change modes here 

Thanks 

[Dustin Anderson]

Cisco option 43

F1 (addresses x4)(Address in hex)

lets take a single address of say 10.20.30.40, so your code would be

F1040A141E28

[tachyon05]

Thanks Everyone.  Using the 10.20.30.40 IP as an example, both generators I linked above produced the same result "F1040A141E28".  This suggests the generators are working correctly.  I am not sure what is TLV.  On Windows DHCP server, I enabled and added option 43 just like I would for option 150 for TFTP server for phones.  The only difference is you can enter IPs in ASCII for option 150.

How do I make my AP forgot the old WLC?

Sorry, but I do not wish to disclose the HEX value.

Thanks for your understanding

[MHM Cisco World]

Ok' we get your point' 

Can you share screen shoot the window Server config you use.

[Rich R]

The only way to work out how/why the AP is doing that is from the full console log of the AP from power-on.  That will tell you exactly what it learns and what decision it makes.

Since you refuse to share any useful diagnostics we cannot help you with interpreting that so you will have to do that yourself.

Keep in mind that AP HA settings will *always* override option 43.
If the AP fails to join the option 43 WLC for any reason (there can be many) then it will try all the others it remembers and can discover (using all possible discovery methods).  Again console log will reveal this.

Good luck but if you want more detailed technical help you'll have to provide more technical detail. 
You can of course share info with key details obfuscated.

> How do I make my AP forgot the old WLC?
Factory default reset