Description
This article describes how FortiGate works in HA with dynamic interfaces (DHCP, PPPoE).
Scope
FortiGate.
Solution
DHCP and PPPOE Support for Active-Passive Mode.
Fortinet recommends turning on DHCP or PPPoE to be turned on for an interface after the cluster has been configured.
Note: If an interface is configured for DHCP or PPPoE, turning on high availability may result in the interface receiving an incorrect address or not being able to connect to the DHCP or PPPoE server correctly.
If any of the FortiGate interfaces have DHCP or PPPoE enabled, HA cannot be enabled or vice versa.
Case 1: DHCP is already enabled on the Interface and HA is set to enable:
From the GUI, when the mode is changed from Standalone to a-p or a-a and select 'Apply', HA mode will switch back to standalone without any error.
From CLI, the only mode available under HA is ‘standalone’, which means the HA is not supported.
FGT1KD-2# config system ha
FGT1KD-2 (ha) # set mode standalone
The system may run in HA A-A or HA A-P mode only when all interfaces are NOT using DHCP/PPPoE as an addressing mode.
Case 2: If the HA is already enabled with A-P or A-A mode and now the mode of the interface is changed from manual to DHCP or PPPoE, the error 'Cannot set mode to DHCP or PPPoE when HA is on' will appear.
In HA A-P mode, when the Interface mode is changed from Manual to PPPoE/DHCP, the Interface mode will switch without any error.
In HA A-A mode, configuring an interface with mode 'PPPoE' and 'DHCP' is not supported; attempting to change the mode from Manual to PPPoE/DHCP would result in the error 'Cannot set mode to 'PPPoE' while HA is in Active-Active mode'.
Error In CLI:
set mode pppoe
Cannot set mode to 'PPPoE' when HA is in Active-Active mode
node_check_object fail! for mode pppoe
value parse error before 'pppoe'
Command fail. Return code -217
Error In GUI:
Note: In case an interface is already configured with the DHCP or PPPoE, the option to configure HA mode with A-A will be unavailable.
In CLI:
config system ha
(ha) # set mode
standalone Standalone mode.
a-p Active-passive mode.
In GUI:
