Technical Tip: How to configure more than one DHCP relay IP on a FortiGate unit
Products
FortiGate v4.0 MR3
FortiGate v5.0
FortiGate v5.4
FortiGate v5.6
FortiGate v6.0
FortiGate v6.2
Description
This article explains how to specify more than one DHCP relay IP, to allow for the coverage of additional LAN subnets.
 
It is possible to set up to 8 IPs from the CLI. This option is also available on GUI since version 5.4.


Solution
For versions before V5.4:

To specify more than one IP for DHCP relay, run from CLI:
#config system interface
edit <REQUIRED_INTERFACE_HERE>
set dhcp-relay-ip <FIRST_IP> <SECOND_IP> ....<EIGHTH_IP>
end
Example:
#config system interface
edit dmz
set dhcp-relay-ip 1.1.1.1 2.2.2.2 3.3.3.3
end
Note: The WebUI will show only 1 IP. The rest of the configuration can be viewed only from CLI.
 
FGT# show system interface dmz
config system interface
edit "dmz"
set vdom "root"
set dhcp-relay-ip "1.1.1.1" "2.2.2.2" "3.3.3.3"
set type physical
next

For versions V5.4 and above:

In GUI:

Go to Network -> Interfaces -> Interface_NAME



Via CLI:
#FGT # config system interface
FGT (interface) # edit port2
FGT (port2) # set dhcp-relay-service enable
FGT (port2) # set dhcp-relay-ip 1.1.1.1 2.2.2.2 3.3.3.3
Last Modified Date: 10-07-2019 Document ID: FD32185