Stateful and Non-Stateful High Availability Prerequisites
CAUTION:SonicWall High Availability does not support dynamic IP address assignment from your ISP.
NOTE: If using only a single WAN IP, note that the backup device, when in Idle mode, will not be able to use NTP to synchronize its internal clock.
TIP: If each SonicWall has a Primary/Backup WAN Management IP address for remote management, the WAN IP addresses must be in the same subnet. If shifting a previously assigned interface to act as a unique WAN interface, be sure to remove any custom NAT policies that were associated with that interface before configuring it.
NOTE: If you are connecting the Primary and Backup appliances to an Ethernet switch that uses the spanning tree protocol, be aware that it may be necessary to adjust the link activation time on the switch port to which the SonicWall interfaces connect. For example, on a Cisco Catalyst-series switch, it is necessary to activate spanning tree port fast for each port connecting to the SonicWall security appliance’s interfaces.