Technical Tip: FortiGate DHCP option 43 configuration for Cisco and Ubiquiti units

[aionescu]

Description
This article describes the format for DHCP option 43 to specify while the FortiGate is configured as DHCP server.

Related documents.

RFC 2132: DHCP Options and BOOTP Vendor Extensions (rfc-editor.org)
Configuring DHCP Option 43 (cisco.com)
UniFi - Layer 3 Adoption for Remote UniFi Network Applications – Ubiquiti Support and Help Center

Solution
If the FortiGate is configured as DHCP server, the following can be used to configure option 43 (Vendor Specific Information) for devices like Ubiquiti or Cisco.
For example, if the controller has the IP address 192.0.2.1, the configuration will look like:

For Ubiquiti.

# config system dhcp server
    edit 1
# config options
    edit 1
        set code 43
        set type hex
        set value 0104c0000201
    end

For Cisco.

# config system dhcp server
    edit 1
# config options
    edit 1
        set code 43
        set type hex
        set value f104c0000201
    end

In this example, c0000201 is the hexadecimal value of the IP address 192.0.2.1.

Related Articles

Technical Tip: DHCP Options