Technical Tip: Deploying Integrated / Infrastructure AP using option 138/43 on Windows DHCP server

[mdeparisse_FTNT]

Description

This article describes how to deploy integrated and infrastructure APs using option 138/43 on a Windows DHCP server.

Integrated and infrastructure APs are able to either boot locally using layer 2 or layer 3 broadcast discovery and are able to find the controller if it resides on the same local subnet / broadcast domain

If the controller is not on the same VLAN as the AP, then the discovering process may either use DNS (wlan-controller name resolution) or using DHCP option.

The DHCP discovering process is the preferred one as it gives granular control per subnet.

Scope

An AP can be deployed across a layer 3 subnet. For this, it is necessary to have either a DHCP server on the subnet where the AP resides, or a remote DHCP server using the DHCP relay.

Solution

Infrastructure AP:

Configure the DHCP server to provide the IP address of the controller to the AP using option 43:

First enter the DHCP Vendor Classes for the corresponding AP model:

In Windows Server

• Open the server manager window and expand the DHCP part.
• Right-click the IPv4 and select Define Vendor Classes.

Add the AP based on the following list:

• Infrastuctured AP300: ASCII Access Point AP822
• Infrastuctured AP1000: ASCII Access Point AP822
• Infrastuctured AP122: ASCII Access Point AP822
• Infrastuctured AP822: ASCII Access Point AP822
• Infrastuctured AP832: ASCII Access Point AP822
• Infrastuctured FAP421: ASCII Access Point FAP421
• Infrastuctured FAP423: ASCII Access Point FAP423

 Select the predefined Options and values window and add a new type using the string option with code 43:

Enter the IP address of the controller

After, add the scope and, in the Scope Options, add the option 43 using the configure Options as shown below, (right-click):

Integrated AP deployment:

• In order to deploy the Integrated AP solution using the DHCP option 138, it is first necessary to translate the IP address into Hexadecimal value. For example: 10.169.2.49 will be translated into 0XAA90231.
• Once this is done, enter the Ctrl Hex value as option 138 using the data type 'long', as shown below.

In the Windows Server:

• Right-click IPv4 and select Set Predefined Options an Values.
• Select Add. Select the 'long' data type and code 138.

To use a different option, configure it on the FortiAP CLI directly using the following command:

FP # cfg -a AC_DISCOVERY_DHCP_OPTION_CODE=139

FP # cfg -c

restarting wtp daemon ...

FP #