How to Configure the Barracuda Load Balancer ADC for High Availability

Configuring the Unit for Clustering

Complete the following steps on each Barracuda Load Balancer ADC you plan to include in the high availability cluster:

1. Go to the ADVANCED > High Availability page.
2. In the Cluster Settings section, specify values for the following:  
   
   1. Enable High Availability – Set Enable High Availability to Yes on both the Barracuda Load Balancer ADCs before clustering. If set to No, the Join Cluster will fail with an error.
   2. Cluster Shared Secret – The passcode that the clustered units use when communicating with one another. It must be the same on both systems.
   3. Cluster Group ID – This must be same on both the Barracuda Load Balancer ADCs that are to be clustered. If other network components on the local network, such as firewalls, are clustered using VRRP then they must use a different ID than this one. Maximum value is 255.
   4. Failback Mode – Set to Automatic if you want the Primary (Active) system to resume Service(s) upon its recovery. When set to Manual, you will need to intervene to return the Service(s) from the Backup unit to the Primary unit upon its recovery.

   5. Monitor Link(s) – Select the interface(s) to be monitored. If the backup system determines that the monitored link is not available on active device, it will become active and assume the virtual IP addresses. The passive Barracuda Load Balancer ADC becomes the active appliance and begins to handle all traffic.

      It is essential that you configure the same interfaces for both the active and passive appliances before you enable high availability. If the Monitor Link(s) configuration does not match, the passive appliance could automatically take over for the active appliance, even though no actual failure has occurred.

3. Click Save Changes to save the settings.

To Cluster Two Barracuda Load Balancer ADCs

To cluster two Barracuda Load Balancer ADCs together, where the primary/active system is designated as Barracuda Load Balancer ADC 1, and the backup/passive system is designated as Barracuda Load Balancer ADC 2:

1. Complete the installation process for each system. 
2. On the ADVANCED > High Availability page of the Barracuda Load Balancer ADC 1, in the Cluster Settings section:
   
   1. Set Enable High Availability to Yes.
   2. Specify values for Cluster Shared Secret, Cluster Group ID, Failback Mode and Failover on Link Down and click Save Changes.
3. On the ADVANCED > High Availability page of the Barracuda Load Balancer ADC 2:
   
   1. Set Enable High Availability to Yes.
   2. Specify values for Cluster Shared Secret, Cluster Group ID and Failback Mode and click Save Changes.These values should be same as the Barracuda Load Balancer ADC 1.
   3. In the Clustered Systems section, enter the management IP address of the Barracuda Load Balancer ADC 1 and click Join Cluster.
   4. The clustering will run as a background task and may take a few minutes to complete. Do not do any other configuration changes while the clustering task is running.
4. After a few minutes, refresh the ADVANCED > High Availability page on both systems and verify the following:
   
   1. Each system's MGMT IP address appears in the Clustered Systems table.
   2. The status of the Primary (Active) system should be .
   3. The status of the Backup (Passive) system should be .

Configuration Synchronization

Join Cluster clears any existing configuration on the backup system and copies the configuration settings from the primary system. When the systems are clustered, the configuration continues to be synchronized once every 2 minutes.