Citrix ADC

Configuring high availability

To set up a high availability configuration, you create two nodes, each of which defines the other’s Citrix ADC IP (NSIP) address as a remote node. Begin by logging on to one of the two Citrix ADC appliances that you want to configure for high availability, and add a node. Specify the other appliance’s Citrix ADC IP (NSIP) address as the address of the new node. Then, log on to the other appliance and add a node that has the NSIP address of the first appliance. An algorithm determines which node becomes primary and which becomes secondary.

The following figure shows a simple HA setup, in which both nodes are in the same subnet.

Figure 1. Two Citrix ADC Appliances Connected in a High Availability Configuration

High availability setup of netscaler appliances

Steps to configure high availability

Setting up a high availability pair of two Citrix ADC appliances consists of the following tasks on both the appliances:

  • Add a node. On an appliance, say N1, add the other appliance, say N2, by specifying a unique node ID and the appliance’s (N2) NSIP address. You can specify any integer in the range of 1-64 for the peer node ID.

    The peer node ID specified on the self-node is applicable only to the self-node and it does not have any relevance on the peer node. For example, you have added N2 as peer node on N1 and specified the node ID as 33 for N2. The N2’s node ID setting as 33 is applicable only on N1 and has no effect on N2’s configuration.

    The peer node ID, specified on both the nodes, need not be of the same value and can be modified. On both the nodes, the self-node ID is hardcoded to zero and cannot be modified.

  • Disable HA monitor for unused interfaces. On the self-node, you must disable the HA monitor for each interface that is not connected or not being used for traffic. Disabling HA monitor for unused interfaces prevents any HA failovers caused when the state of any of these unused interfaces becomes DOWN.

Note:

To ensure that each node in the high availability configuration has the same settings, you must synchronize your SSL certificates, startup scripts, and other configuration files with those on the primary node.

CLI procedures

To set up a high availability pair of two Citrix ADC appliances by using the CLI, perform the following tasks on each of the two appliances:

To add a node by using the CLI:

At the command prompt, type:

  • add ha node <id> <IPAddress>
  • show ha node

To disable the HA monitor for an unused interface by using the CLI:

At the command prompt, type:

  • set interface <ifNum> [-haMonitor ( ON | OFF )]
  • show interface <ifNum>

Example:

> add ha node 33 203.0.113.33

> set interface 1/3 -haMonitor OFF
 Done
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GUI procedure

The Citrix ADC GUI provides a screen that combines the tasks of adding a peer node as well as disabling the HA monitor on unused interfaces on the self-node. The screen also provides an option to automatically configure the peer node for the HA setup avoiding the need to manually configure the peer node.

To set up a high availability pair of two Citrix ADC appliances by using the GUI:

  1. Log on to the GUI of one of the appliances.
  2. Navigate to System > High Availability > Nodes, provide the peer node’s NSIP address in the Remote Node IP Address field.
  3. Select Turn Off HA Monitor interface/channels that are down.
  4. Select Configure remote system to participate High Availability setup and provide the peer node’s login credentials.
  5. Click Create.

Disabling or Enabling a Node

You can disable or enable only a secondary node. When you disable a secondary node, it stops sending heartbeat messages to the primary node, and therefore the primary node can no longer check the status of the secondary. When you enable a node, the node takes part in the high availability configuration.

To disable or enable a node by using the command line interface

At the command prompt, type one of the following commands:

  • set ha node -hastatus DISABLED
  • set ha node -hastatus ENABLED

To disable or enable a node by using the GUI

  1. Navigate to System > High Availability and, on the Nodes tab, open the node.
  2. In the High Availability Status list, select ENABLED (Actively Participate in HA) or DISABLED (Do not participate in HA).
Configuring high availability