This procedure applies for DHCP Windows Server 2003, 2008 and 2012.

Open the DHCP Tool, Right click on IPV4 at the top once you previously connected to the actual DHCP Server and Select DEFINE VENDOR CLASSES (VCI).

Click ADD in order to include a new VCI in the DHCP Server (on this case I deleted the Cisco 3500 Series Class and recreated it)

Introduce the Display Name, Description and FILL the ASCII Field with the proper VCI value which you can obtain from: http://www.cisco.com/c/en/us/support/docs/wireless-mobility/wireless-lan-wlan/97066-dhcp-option-43.html. IMPORTANT TO MENTION, that on: “Cisco AP c3500 value” there is a BLANK SPACE between each word. CLICK OK to add the NEW VCI into the DHCP

Now you can see the NEW Vendor Class added to the LIST in the DHCP. CLICK Close to return to the DHCP Main Window.

Right Click on IPV4 and select SET PREDEFINED OPTIONS

FROM the OPTION CLASS window, scroll down and select the Vendor Class created before for the WLC 3500. CLICK OK.

A new PREDEFINED OPTIONS Window with the value selected before is shown. CLICK ON ADD

A new window OPTION TYPE is displayed so you must fill the fields with the corresponding values for this AP 3500 VCI Case

In the FIELD = NAME put the name that you want to use for this case. I put Option 43 in order to recognize what that Option is for. On the DATA TYPE, Select IP ADDRESS.

CHECK the ARRAY box so you can configure the IP ADDRESS of one or some WLC’s on which the 3500 AP can connect later. The SUB-OPTION Code must be equal to 241. Fill the DESCRIPTION Field with any value that describes for what kind of AP is this option created. Finally CLICK OK.

Now you can see the OPTION NAME and DESCRIPTION for this OPTION CLASS. Next, click on ARRAY in order to include the IP Address of the WLC to which the AP 3500 will connect.

A new window IP ADDRESS ARRAY EDITOR is displayed so you can add the WLC IP ADDRESS to which the 3500 will connect. INTRODUCE the IP ADDRESS and then CLICK ADD. DO NOT PRESS OK yet.

Now you can see the IP ADDRESS of the WLC added to the Option 43 for the 3500 AP Series. CLICK OK to continue.

Now back on the PREDEFINED OPTIONS WINDOW, you can see the IP ADDRESS of the WLC configured for the DHCP Option 43 of the AP 3500 Series. Click OK to continue.

Now you need to assign that NEW OPTION 43 into the global configuration of the DHCP Server so it can apply it to each scope. Therefore, Select SERVER OPTIONS which is Global in the DHCP Configuration. BE CAREFUL so you do not select the SERVER OPTIONS of an specific SCOPE already configured in the DHCP Server.

Right CLICK on SERVER OPTIONS and then Select CONFIGURE OPTIONS

A new Window SERVER OPTIONS opens. SELECT ADVANCED and then SCROLL DOWN and locate the DHCP Option previously created. ON THIS CASE = Cisco 3500 Series AP. DO NOT CLICK OK because another window will open.

Another information is displayed once you selected before the Cisco 3500 Series AP Option. SELECT the box on the left side that says 241 Option 43.

Once you checked the box, the INFORMATION about the WLC IP ADDRESS is displayed. YOU CAN MODIFY this value as I am showing later on this procedure. CLICK APPLY ONLY.

Now you can see that the WLC IP ADDRESS was added to the OPTION CLASS for the 3500 AP. CLICK OK to close this window and return to the DHCP Main Window.

On the right side of the DHCP Main Window you will see how the OPTION 43 for the AP 3500 was globally added in the DHCP SERVER OPTIONS, in particular for the OPTION 43.

If you open any individual SCOPE, you will see that OPTION 43 for AP 3500 was automatically added. YOU CAN REMOVE MANUALLY this option from every SCOPE individually as you require.

If you want to modify the WLC IP ADDRESS for an SPECIFIC SCOPE. Right Click on the SCOPE OPTIONS and Select CONFIGURE OPTIONS.

Select ADVANCED and scroll down looking for the SPECIFIC OPTION that you want to modify. In our case is the 3500 AP Series.

GO to the IP ADDRESS portion of the Window displayed and select add or remove as you need.

In this case, I added on the OPTION 43 for the 3500 AP another WLC IP ADDRESS = 172.23.111.40. CLICK ADD to include this value into the OPTION.

Now you can see that another WLC IP ADDRESS was included into the DHCP OPTION 43 for the 3500 AP. Click APPLY and then OK to return to the DHCP Main Window.

If you check on the RIGHT SIDE, an additional IP ADDRESS for the DHCP OPTION 43 of the 3500 AP was added. This IP ONLY APPLIES to that specific SCOPE of the DHCP.

If you check on the SERVER OPTIONS of the GLOBAL CONFIGURATION of the DHCP Server, you will see that OPTION 43 for the Cisco 3500 AP has not changed. So the previous modification only APPLIED as I mentioned to an specific SCOPE.