Technical Note: Configuring HA on a FortiGate that has DHCP or PPPoE interfaces

[Sabk_FTNT]

Description

HA configuration is not taken into account on any FortiGate units with network interfaces configured to request an IP address through the DHCP service (on 5.2.x and earlier releases).

GUI

When the HA mode is set to Active-Passive or Active-Active, on validation it will return to Standalone:

After the validation, HA Mode is back to standalone, without any warning.

CLI

The “set mode” command is not accepted:

FG100D-2 # config system ha
FG100D-2 (ha) # set mode a-p

command parse error before 'mode'

Command fail. Return code -61

Scope
All FortiGate units with the default setting "DHCP addressing mode" on some network interfaces running 5.2.x and earlier releases only.

Note1: On 5.4.x, 5.6.x and later firmware releases, dhcp/pppoe interface configuration in HA is supported. Fortinet recommends that you turn on DHCP or PPPoE addressing for an interface after the cluster has been configured.

Solution
On 5.2.x and previous releases, the solution is to make sure that no network interface is set to the "DHCP addressing mode", before enabling the HA feature.

Change the interface IP addressing mode to "Manual":

GUI

CLI

FG100D-2 # config system interface
FG100D-2 (interface) # edit wan1
FG100D-2 (wan1)# set mode
static    static setting
dhcp      extenal dhcp client mode
pppoe     external pppoe mode
FG100D-2 (wan1) # set mode static
FG100D-2 (wan1) # end

Note: On the FortiGate 100D hardware platform, by default, network interfaces WAN1 and WAN2 are set to the "DHCP" IP addressing mode.

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