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SONICWALL SONICOS ENHANCED 2.5 ADMINISTRATOR’S GUIDE
C
HAPTER
37:
Setting Up Hardware Failover
Log into the Backup SonicWALL’s unique LAN IP address. If this SonicWALL security appliance has
not been registered at mySonicWALL.com, register it. The Management Interface should now display
Logged Into: Backup SonicWALL Status: (green ball) Active in the upper-right-hand corner.
Now, power the Primary SonicWALL back on, wait a few minutes, then log back into the Management
Interface. The Management GUI should again display Logged Into: Primary SonicWALL Status:
(green ball) Active in the upper-right-hand corner.
If you are using the Monitor Interfaces feature, experiment with disconnecting each monitored link to
ensure everything is working correctly.
Forcing Transitions
In some cases, it may be necessary to force a transition from one active SonicWALL to another – for
example, to force the primary SonicWALL to become active again after a failure when Preempt Mode
has not been enabled, or to force the backup SonicWALL to become active in order to do preventive
maintenance on the primary SonicWALL.
To force such a transition, it is necessary to interrupt the heartbeat from the currently active
SonicWALL. This may be accomplished by disconnecting the active SonicWALL’s LAN port, by
shutting off power on the currently active unit, or by restarting it from the Web Management Interface.
In all of these cases, heartbeats from the active SonicWALL are interrupted, which forces the currently
Idle unit to become Active.
To restart the active SonicWALL, log into the primary SonicWALL LAN IP Address and click Tools on
the left side of the browser window and then click Restart at the top of the window.
Click Restart SonicWALL, then Yes to confirm the restart. Once the active SonicWALL restarts, the
other SonicWALL in the Hardware Failover pair takes over operation.
S
Alert: If the Preempt Mode checkbox has been checked for the primary SonicWALL, the primary unit
takes over operation from the backup unit after the restart is complete.
Adjusting Hardware Failover Settings
On the Hardware Failover>Settings page, there are three user-configurable timers that can be
adjusted to suit your network’s needs:
• Heartbeat Interval (seconds) – This timer is the length of time between status checks. By default
this timer is set to 5 seconds; using a longer interval will result in the SonicWALL taking more time
to detect when/if failures have occurred.
• Failover Trigger Level (missed heart beats) – This timer is the number of heartbeats the
SonicWALL 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 SonicWALL
fails over.
• Election Delay Time – This timer can be used to specify an amount of time the SonicWALL will
wait to consider an interface up and stable, and is useful when dealing with switch ports that have
a spanning-tree delay set.