WLC 9800-40, 9120 AP with vlan group DHCP IP Learn

[Himel]

Hi I'm a beginner-intermediate level network engineer. I need to configure management ip(One ip block for management for wlc and all wap) and one for DHCP lease. WLC is on local mode & internal DHCP, Dhcp pool reserved disabled. I configured  Vlan 614 for management and vlan 211 for dhcp ip lease. Switch access ports are configured to vlan 614 for wap and static ip assigned from vlan 614. But problem is sometimes the wlc gives ip to clients sometimes it's stuck on ip learn. What is the solution for this?

[balaji.bandi]

When you are configuring an internal DHCP Server on the C9800 if you are having issues with clients not getting a DHCP IP address make sure “DHCP reserved” is disabled!

if you have done that already, then you need to do packet capture why DHCP IP is not offered.

[Himel]

Its already disabled

[marce1000]

 -  Review the WLC 9800-40 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.               Checkout all advisories!

 M.

[Himel]

No errors

[Arshad Safrulla]

Hi Himel,

It is not recommended to run internal DHCP server in the WLC itself as it has lot of limitations. It is recommended that you host DHCP services somewhere else in your network.

If you are expecting WLC to work as the DHCP server for the WLANs it is advertising, then you need to have specific sets of configurations.

https://www.cisco.com/c/en/us/products/collateral/wireless/catalyst-9800-series-wireless-controllers/guide-c07-743627.html#:~:text=dhcp%2Dsubnet%2Doptions-,Internal%20DHCP%20server,-The%20controller%20has

Cisco Catalyst 9800 Series Wireless Controller Software Configuration Guide, Cisco IOS XE Amsterdam 17.3.x - DHCP for WLANs [Cisco Catalyst 9800 Series Wireless Controllers] - Cisco

Also, if you are planning on using the WLC DHCP server for AP Management, please keep in mind that WLC doesn't support advertising option 43.

[Rich R]

And make sure you're running a recommended version of software (see link in my signature)