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 HCL 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).