The following hardware and software requirements must be met to provide HA failover or cluster functionality:
- Valid license with the high availability option enabled (for the stand-by unit you only need an additional base license).
- Two Sophos UTM units with identical software versions and hardware or two Sophos UTM appliances of the same model.
- Heartbeat-capable Ethernet network cards. Check the HCLHardware Compatibility List to figure out which network cards are supported. The HCL is available at the Sophos Knowledge Base (use "HCL" as search term).
- Ethernet crossover cable (for connecting master and slave in a hot standby system). Sophos UTM appliance models 320, 425, and 525, whose dedicated HA interface is a Gigabit auto-MDX device, can be connected through a standard IEEE 802.3 Ethernet cable as the Ethernet port will automatically exchange send/receive pairs.
- Network switch (for connecting cluster nodes).