Product Documentation

Configure High Availability Set up on the Appliances

High availability(high availability) works directly between the NetScaler instances of two SD-WAN 4100 or 5100 appliances. As shown in the configuration, the two appliances are configured almost identically, except for management network IP addresses.


  1. The accelerator instances on the two appliances are not synchronized, and must be kept consistent manually. Take this into account when deciding whether to use high availability.
  2. For a smooth installation, install and test one appliance before adding the second one, noting all configuration changes, especially to the accelerator.
  3. You must use the same aPA and signaling addresses on both appliances. However, all management subnet IP addresses must be unique on each appliance.

If the active appliance becomes unavailable, the passive appliance transparently takes over the function of the primary appliance. This is called “failover.” As a result, disruption of services over the network is minimal. After a failover, all clients must reestablish their connections to the managed servers, but the session persistence rules are maintained as they were before the failover.

High availability is supported in all deployment modes, and the high availability configuration procedure is the same for all modes. The two appliances should be running identical hardware, licensing, and software releases, and must be deployed identically, using the same deployment modes on the same subnets.

When you enable high availability, the configuration of the primary appliance’s NetScaler instance is copied to the secondary appliance as part of the NetScaler high availability synchronization process.

To configure a high availability setup of NetScaler instances

  1. Complete the configuration for your chosen deployment mode (inline or WCCP). > Note that all parameters for the external traffic subnet and the private traffic subnet are identical for both appliances, but some management subnet values are different on the two appliances.
  2. Fully configure appliance and test it thoroughly. If inline mode is used, do not connect the traffic network to the bridge ports on appliance.
  3. Fully configure appliance. Some parameters are different on the two appliances: H1, H4, H5, H6, and H17 are used on the second appliance in place of M1, M4, M5, M6, and M17. Make sure that the accelerators are configured identically to the ones on appliance, and that both appliances have identical VLAN definitions in the NetScaler instances.
  4. Access the NetScaler instance on appliance by specifying its IP address (M17) in a web browser.
  5. Log on to the NetScaler instance.
  6. In the Navigation pane, expand the System node.
  7. Select the High Availability node.
  8. Click Add to configure a high availability setup of the NetScaler instances.
  9. In the remote Node IP Address field of the High Availability Setup dialog box, specify the NSIP address of the NetScaler instance of the other appliance (H17 on your worksheet).
  10. Click OK. The appliances are now configured as a high availability pair.


To learn more about setting up high availability on a NetScaler instance, see the High Availability node of the Citrix eDocs website.

Configure High Availability Set up on the Appliances

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