Configuring High Availability; Configuring Advanced Ha Settings - SonicWALL NSA 2400 Getting Started Manual

3. Make sure the Primary SonicWALL and Backup
SonicWALL security appliances' LAN, WAN and other
interfaces are properly configured for failover.
4. Connect the X5 ports on the Primary SonicWALL and
Backup SonicWALL appliances with a CAT6-rated
crossover cable (red crossover cable). The Primary and
Backup SonicWALL security appliances must have a
dedicated connection. SonicWALL recommends cross-
connecting the two together using a CAT 6 crossover
Ethernet cable, but a connection using a dedicated
100Mbps hub/switch is also valid.
5. Power up the Primary SonicWALL security appliance, and
then power up the Backup SonicWALL security appliance.
6. Do not make any configuration changes to the Primary's
X5; the High Availability configuration in an upcoming step
takes care of this issue. When done, disconnect the
workstation.

Configuring High Availability

The first task in setting up HA after initial setup is configuring the
High Availability > Settings page on the Primary SonicWALL
security appliance. Once you configure HA on the Primary
SonicWALL security appliance, it communicates the settings to
the Backup SonicWALL security appliance.
To configure HA on the Primary SonicWALL, perform the
following steps:
1. Navigate to the High Availability > Settings page.
2. Select the Enable High Availability checkbox.
3. Under SonicWALL Address Settings, type in the serial
number for the Backup SonicWALL appliance.
You can find the serial number on the back of the SonicWALL
security appliance, or in the System > Status screen of the
backup unit. The serial number for the Primary SonicWALL is
automatically populated.
4. Click Apply to retain these settings.

Configuring Advanced HA Settings

1. Navigate to the High Availability > Advanced page.
2. To configure Stateful HA, select Enable Stateful
Synchronization. A dialog box is displayed with
recommended settings for the Heartbeat Interval and
Probe Interval fields. The settings it shows are minimum
recommended values. Lower values may cause
unnecessary failovers, especially when the SonicWALL is
under a heavy load. You can use higher values if your
SonicWALL handles a lot of network traffic. Click OK.
Tip:
Preempt mode is automatically disabled after enabling
Stateful Synchronization. This is because preempt
mode can be over-aggressive about failing over to the
backup appliance. For example if both devices are idle,
preempt mode may prompt a failover.
SonicWALL NSA 2400 Getting Started Guide Page 27