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WLC 4400 - DHCP Relay Prob.

Help Please. We have been trying to get a new WLC4400 and LAP1121Gs to hand out IP addresses to wireless clients. Here is the network layout.

-Win2003 DHCP server is X.X.64.2 (64 subnet)

-DHCP relay is setup on X.X.80.x subnet and current wireless clients get IP addresses from "thick" APs

-WLC4400 Management interface is X.X.80.100

-Test AP1121G is X.X.80.106

When the AP was setup initially for DHCP it got an IP address from the DHCP server. The 4400 can ping the DHCP server. Laptops associated with the thin AP never get an IP address from DHCP.

I can statically assign an IP to my laptop it connects to the thin AP and can browse the network.

When I hooked up a sniffer and took a look at the DHCP packets coming out of the 4400. I see only Discover packets coming out with no returns, no further request, or nacks.

I have specified the DHCP server Address in both the Controller - Interface - Management section and also in the WLAN - DHCP Server section.

Any ideas?

Woody

5 REPLIES

Re: WLC 4400 - DHCP Relay Prob.

Woody,

On your controller do you have the virtual address configured? Normally we recommend that you use 1.1.1.1 as your virtual IP, as this is only used for the DHCP relaying,which is unicast to the DHCP server that is configured, and for Webauth. If you could post the output of some commands from the CLI and some debugs I can give you some further information. The show commands are show interface detail ap-manager, show interface detail management, show interface detail service-port, show interface detail virtual. And the debug would be, debug dhcp message enable.

HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
New Member

Re: WLC 4400 - DHCP Relay Prob.

Thanks for your reply. I attached a txt file with output from your suggested commands. I do the virtual interface configured but I'm not sure if it is configured correctly.

Thanks again!

Woody

New Member

Re: WLC 4400 - DHCP Relay Prob.

Can you paste your show interface from your WLC? I recently setup our WLC4404-100. I used a external Windows DHCP server and I didn't have any problem.

Is your WLC trunk? You must create an interface on the WLC for the DHCP scope you plan to deploy.

New Member

Re: WLC 4400 - DHCP Relay Prob.

David, please see my posting above as it has the an attachment displaying the show interface X command output.

Our WLC is configured with the Management interface on the 80.x subnet. Our DHCP server lives on on the 64.x subnet. I tried moving the WLC and LWAPs to the 64.x subnet DHCP relay worked perfectly. Seems DHCP discover packet the WLC sends from the 80.x subnet (Wireless subnet) never receives a reply so there is something unique about what the WLC is sending.

On the 80.x subnet we currently have "thick" APs and wireless clients that are able to receive addresses from the DHCP server living on the 64.x subnet.

Woody

New Member

Re: WLC 4400 - DHCP Relay Prob.

Woody,

You need to create an interface on the VLAN you're leasing address on. In this case, on your WLC, please create an interface x.x.64.3.

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