WLAN Controller DHCP confusion.

Answered Question
May 24th, 2007

Hello all.


I am slightly confused as the DHCP configuration on the WLAN controllers. I have created WLAN SSID 'test' assigned to dynamic interface 'test' using vlan 410. I want my WLAN clients to use DHCP to get their IP addresses when associated/authenticated to SSID 'test'.


My confusion is where to do this. I see that I can do this on BOTH the SSID (WLANs>Edit>Advanced) AND the interface (CONTROLLER>Interfaces). Why is there two places to do this and what is the difference between the two?


I am using software version 4.1.171.0.


Many thanks for any help


Darren

Correct Answer by ankbhasi about 9 years 9 months ago

Hi Darren,


Its just an additional feature. The WLAN(s) by default use the primary DHCP server that is defined on dynamic interface. Now if you have more than one WLAN defined on a dynamic interface, and you want each WLAN to have its own DHCP pool defined on different DHCP servers. At that point you would define a DHCP override on the WLAN to not use the default as defined on the dynamic interface.


The DHCP override can also be used if you are moving/rebuilding DHCP servers, so if you need to set a temporary DHCP server. You can specify the temporary one through the use of the DHCP override.


HTH


Ankur


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ankbhasi Thu, 05/24/2007 - 05:52

Hi Darren,


WLANs can be configured to use the DHCP servers. Two types of DHCP servers are available: internal and external.


You can use controller itself as a DHCP server and if you want you can also have an external DHCP server for your wireless clients.


DHCP Assignment


You can configure DHCP on a per-interface or per-WLAN basis. The preferred method is to use the primary DHCP server address assigned to a particular interface.


You can also define a DHCP server on a WLAN. This server will override the DHCP server address on the interface assigned to the WLAN.


See if this link helps you


http://www.cisco.com/univercd/cc/td/doc/product/wireless/control/c44/ccfig41/c41wlan.htm#wp1108097


Please come back if you have doubts.


HTH


Ankur


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darrenj Thu, 05/24/2007 - 06:16

Thanks for the response, it makes sense now. What still baffles me though, is why have two places to set this up? Why not, have just one place on the interface where you set-up DHCP parameters?


Thanks gain.

Correct Answer
ankbhasi Thu, 05/24/2007 - 06:38

Hi Darren,


Its just an additional feature. The WLAN(s) by default use the primary DHCP server that is defined on dynamic interface. Now if you have more than one WLAN defined on a dynamic interface, and you want each WLAN to have its own DHCP pool defined on different DHCP servers. At that point you would define a DHCP override on the WLAN to not use the default as defined on the dynamic interface.


The DHCP override can also be used if you are moving/rebuilding DHCP servers, so if you need to set a temporary DHCP server. You can specify the temporary one through the use of the DHCP override.


HTH


Ankur


*Pls rate all helpfull post

Michael Dyer Thu, 08/09/2012 - 20:13

Ankur,


I'm setting up a school system with a WLC located at the central school board site and 1142APs setup at each remote school campus.  Each of the eight remote school campus has it's own DHCP server for local 10.X.X.X IP addresses.  As a result of using Class A 10.1.0.0/16, 10.2.0.0/16, 10.3.0.0/16  etc network addresses at each remote school campus there should be more than enough addresses available for both remote campus school hardware and student clients. 


The issue I have is everything in currently configured for a single VLAN, VLAN 1.  I would like to configure a separate WLAN for teachers/staff, WLAN for students, and WLAN for TechSupport and put each of those WLANs in it's own VLAN for security and performance reasons.  Since each remote campus has a single DHCP server should I create separate scope's in the existing MS DHCP server, use a combination of internal and external DHCP servers (ie internal for wireless clients, external for everything else), or standup an additional MS server at each remote site?


Also, ifor each WLAN interface created and associated interface into that WLAN there will need to be a separate VLAN created on the L3 device so it can direct traffic to the centrally located WLC, right?


So many DHCP servers, so little time....  Any direction you can send my way will be greatly appreciated.


Warm Regards,


Michael 

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