DELL NSAE6500 User Manual

Configuring a Stateful HA Pair   |   

38

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 appliance is 

under a heavy load. You can use higher values if your 

SonicWALL handles a lot of network traffic. Click OK.

3.

To cause the HA pair to change back to the original primary 

unit when it becomes available after a failover, select the 

Enable Preempt Mode checkbox.

4.

To backup the firmware and settings when you upgrade the 

firmware version, select Generate/Overwrite Backup 

Firmware and Settings When Upgrading Firmware.

5.

Select the Enable Virtual MAC checkbox. Virtual MAC 

allows the primary and secondary appliances to share a 

single MAC address. This greatly simplifies the process of 

updating network ARP tables and caches when a failover 

occurs. Only the WAN switch that the two appliances are 

connected to needs to be notified. All outside devices will 

continue to route to the single shared MAC address.

6.

Optionally adjust the Heartbeat Interval to control how 

often the two units communicate. This timer is the length of 

time between status checks. By default this timer is set to 

5000 milliseconds, the minimum recommended value is 

1000 milliseconds. Using a longer interval will result in the 

appliance taking more time to detect when/if failures have 

occurred. Less than this may cause unnecessary failovers, 

especially when the appliance is under a heavy load. 

7.

Set the Probe Interval for the interval in seconds between 

communication with upstream or downstream systems. 

This timer controls the path monitoring speed. Path 

monitoring sends pings to specified IP addresses to 

monitor that the network critical path is still reachable. The 

default is 20 seconds, and the allowed range is from 5 to 

255 seconds. It is recommended that you set the interval 

for at least 5 seconds. You can set the Probe IP 

Address(es) on the High Availability > Monitoring 

screen.

8.

In the Probe Count text-field, enter the desired number of 

consecutive probes before the appliance considers the 

network critical path to be reachable or broken. The 

minimum and default is 3 probes, and the maximum is 10.

9.

Typically, Dell SonicWALL recommends leaving the 

Failover Trigger Level (missed heart beats), Election 

Delay Time (seconds), and Dynamic Route Hold-Down 

Time fields to their default settings. These fields can be 

tuned later as necessary for your specific network 

environment.
• The Failover Trigger Level (missed heart beats) timer 

is the number of heartbeats the appliance will miss before 
failing over. By default, this time is set to 5 missed heart 
beats.This timer is linked to the Heartbeat Interval timer – 
for example, if you set the Heartbeat Interval to 10 
seconds, and the Failover Trigger Level timer to 5, it will 
be 50 seconds before the appliance fails over.