DHCP on WLC in DHCP Proxy mode

[SabeelShakeel00430]

Hi,

I will be migrating some wireless traffic that passes via our WLC from one ISP to another. The new ISP is using their gateway as a DHCP relay (as server sits in the WAN), and The wireless clients are proxying their DHCP requests via the wireless LAN controller.

I attempted this migration last week, but it was unsuccessful as the clients were not receiving IP addresses. After checking a wireshark capture i saw the controller sending a Discover message and it received an Offer from the gateway, but there was no Request sent from the controller afterwards. 

My initial thoughts is that the Controller's DHCP settings need adjusting due to this set-up, as they were not changed and the controller looks like it could be the problem. I did notice that option 82 has not been checked and think this may be the issue, but need confirmation if creating the WLC as a relay agent in dhcp proxy mode would actually help.

Please advise as soon as you can. I have also put the flow at the bottom:

Logical:

Client>>>AP>>>WLC>>>Gateway/DHCP Relay>>>DHCP Server

Physical:

Client>>>>AP>>>>Access Switch>>>>WLC>>>>Access Switch>>>>Distribution Switch>>>Firewall>>>WAN Switch>>>Router/Gateway/DHCP Relay>>>Server

Best Regards,

Sabeel

[Arshad Safrulla]

Hi Sabeel,

Which platform of WLC is this? What is the Code running? AP models and the clients you tried with. And where do you have the L3 interface for the VLAN's where the clients are connecting?

Bridge mode is recommended by Cisco and will suit the most for your scenario. So try changing it to bridge mode and then check. You must use proxy mode only in certain scenarios and not all the clients are happy to connect to Wireless when in proxy mode.