Cisco WLC 5508 DHCP issues

[JDMJeffy84]

Hello guys,Need some assistance on DHCP settings.
We currently have 2 DHCP settings on our controller.

we have 1 Vlan Corporate which points to our Internal DHCP Server and the other GUEST we point it to our controller to serve out IP Addresses.

Issue we have is if the option in:Controller/Advanced/DHCP:

Enable DHCP proxy is ticked  - it stops Corporate clients getting IP Address - fails to 169.254.x.x and Guest clients can happily get IP Address from DHCP from the controller. If the DHCP Proxy is unticked it's vice versa.

Any ideas?

Thanks

[Scott Fella]

DHCP proxy is required if you have a DCHP scope configured on the WLC.  DHCP Proxy should not affect your corporate users as long as dhcp is not being handled by an ASA or a dhcp server that doesn't like the dhcp request coming from a proxy. 

Thanks,

Scott

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[JDMJeffy84]

Ok if that needs to be enabled then my current setup is affecting corporate ><

If I debug dhcp message on controller I get the following messages:

DHCP Forwarding DHCP packet (332 octets)                      -- packet received on direct-connect port requires forwarding to external DHCP server. Next-hop is 192.168.x.x (= default gateway)

Seems to me it's not contacting the Internal DHCP server?

Thanks

[Scott Fella]

What dhcp server are you using for corporate... Microsoft?

Thanks,

Scott

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[Stephen Rodriguez]

Is the DHCP server on the same subnet as the client, or is it on your 'management/server' VLAN?

Per best practices, it is not recommended to have a server on a dynamic interface.

HTH,
Steve

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[JDMJeffy84]

Yes it's on Microsoft 2008 R2

DHCP server is on a seperate subnet (server VLAN)

Corporate on a different subnet 192.168.255.0 but has an IP helper address on L3 switch to get to DHCP

Management subnet for controller & APs on 192.168.222.0

Thanks

Stephen: reading your old post: https://supportforums.cisco.com/thread/2139441

Mgmt via wireless is enabled

[JDMJeffy84]

Oh think I've solved it!

Under Controller/Advanced/DHCP

I've set DHCP Option 82 Remote Id field format from AP-MAC to AP-ETHMAC.

I can now get IP Address for corporate and guest. Not sure whta that option does but it's worked?

Any suggestions?

Many Thanks

[Sahil Mengi · Accepted solution]

DHCP option 82 is a king of enhancement specifically employed for distributed DHCP/relay enviornments.

Using this option, relays insert specific information to the request, for to get an idea of clients physical point of attachment or first interaction to the network.

Here is one good blog post i could find,

http://blog.ine.com/2009/07/22/understanding-dhcp-option-82/

Thanks

Sahil

[Scott Fella · Accepted solution]

Here is a good video:

http://www.youtube.com/watch?v=xs3_Udm9Ipo

Thanks,

Scott

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