WLC DHCP Settings - Under Dynamic Interface configuration

[kfarrington]

Hi Guys,

If I have a dynamic interface that is connected to a subnet where the router interfaces have DHCP servers configured under the helper address commands, do I need to configure the DHCP fields under the dynamic interface configuration?

I have helper address configured on the connected routers AND these fields configured with the same DHCP servers.

Just wondering if I can take the IPs out of the WLC configuration?

Many thx indeed,

Ken

[Stephen Rodriguez · Accepted solution]

Ken, the DHCP address under the dynamic interface, is the address the WLC will unicast the DHCP request to when a client tries to use that interface. Under normal operation this address is needed. There is a way to get the WLC to bridge the packet to the wire so that it is a broadcast instead of a unicast packet. CLI command is config dhcp proxy disable.

But I do believe that even if you issue the CLI command, the software wants the DHCP address listed under the dynamic interface.

HTH,

Steve

[kfarrington]

Hi Steve,

Thanks very much for the speed response.

That is excellent. I will just leave them in there.

Cool.

Thx

Ken

[djkim]

Hi Steve,

I got a question for you. I can't get DHCP working from WLC DHCP scope. where as I could get DHCP server working from DHCP server running from a different VLAN. Can you pls advise any idea of why DHCP in WLC is not working. If you need more detail, pls advise.

Many Thanks, DJ

[Stephen Rodriguez]

hit the CLI of your controller, and issue the following command.

show dhcp proxy

if proxy is disabled the WLC can't act as a DHCP server. to enable, config dhcp proxy enable.

If proxy is enabled, make sure you are listing the management IP as the DHCP server.

HTH,

Steve

[djkim]

Thanks for your reply, I can see that DHCP server ip address is not set as management IP address. I will change it and let you know the result.

Other thing I found I was not able to change DHCP server IP address thru GUI like Controllers > Interfaces > interface name. it keeps saying "could not setup a DHCP server" Is this a known issue? Regards, DJ

[Stephen Rodriguez]

happens sometimes if you only have one DHCP server, try putting 0.0.0.0 as the second server.

[djkim]

If management ip is added as DHCP server, the eror doesn't come up any more. I think the error msg could be more meaningful to help troubleshooting.

Steve - I tried with management IP as DHCP server, it works OK now. appreciate your help.

Now my challenge is security on WLC2112. can you pls point to an url in Cisco.com?

Thanks, DJ

[Stephen Rodriguez]

http://www.cisco.com/en/US/docs/wireless/controller/4.2/configuration/guide/c42sol.html

Chapter 5