A FortiGate cluster can have a firmware upgrade applied in a similar way as you would upgrade a single standalone FortiGate router. To upgrade firmware in a FortiGate HA cluster you simply download the Firmware image you wish to apply then log into the FortiGate and navigate to the System Information section on the Dashboard. In the System Information window the Firmware version is stated, next to this you can click Upgrade, select the downloaded firmware and click OK.
The FortiGate unit will perform the firmware upgrade without interruption to the traffic passing through it. After the standby unit is upgraded this takes on the role of being the active router. The firmware is then upgraded on the other router automatically until both routers are on the latest firmware.
You must always check the release notes that accompany the firmware you’re loading on to the device. In all recent releases of firmware there is a minimum version requirement you may need to be on beforehand in order to upgrade your router successfully. For Example the release notes for FortiOS v4.0 MR3 Patch Release 10 build 0639 officially supports upgrade from :
- FortiOS v4.0 MR3 GA or later
- The latest v4.0 MR2 release