Product documentation
Citrix ADC
Current Release 13.0 12.1 11.1
View PDF

Configure high availability

September 14, 2021
Contributed by:
C

You can deploy two Citrix ADC appliances in a high availability configuration, where one unit actively accepts connections and manages servers while the secondary unit monitors the first. The Citrix ADC appliance that is actively accepting connections and managing the servers is called a primary unit and the other one is called a secondary unit in a high availability configuration. If there is a failure in the primary unit, the secondary unit becomes the primary and begins actively accepting connections.

Each Citrix ADC appliance in a high availability pair monitors the other by sending periodic messages, called heartbeat messages or health checks, to determine the health or state of the peer node. If a health check for a primary unit fails, the secondary unit retries the connection for a specific time period. For more information about high availability, seeHigh Availability. If a retry does not succeed by the end of the specified time period, the secondary unit takes over for the primary unit in a process called failover. The following figure shows two high availability configurations, one in one-arm mode and the other in two-arm mode.

Figure 1. High availability in one-arm mode

image

Figure 2. High availability in two-arm mode

image

In one-arm configuration, both NS1 and NS2 and servers S1, S2, and S3 are connected to the switch.

在手臂配置中,NS1 NS2都反对nected to two switches. The servers S1, S2, and S3 are connected to the second switch. The traffic between client and the servers passes through either NS1 or NS2.

To set up a high availability environment, configure one ADC appliance as primary and another as secondary. Perform the following tasks on each of the ADC appliances:

  • Add a node.
  • Disable high availability monitoring for unused interfaces.

Add a Node

A node is a logical representation of a peer Citrix ADC appliance. It identifies the peer unit by ID and NSIP. An appliance uses these parameters to communicate with the peer and track its state. When you add a node, the primary and secondary units exchange heartbeat messages asynchronously. The node ID is an integer that must not be greater than 64.

Through CLI

To add a node by using the command line interface, follow these steps:

At the command prompt, type the following commands to add a node and verify that the node has been added:

  • add HA node

  • show HA node

    Example

    add HA node 0 10.102.29.170 Done > show HA node 0 1) Node ID: 0 IP: 10.102.29.200 (NS200) Node State: UP Master State: Primary SSL Card Status: UP Hello Interval: 200 msecs Dead Interval: 3 secs Node in this Master State for: 1:0:41:50 (days:hrs:min:sec)

Through GUI

To add a node by using the GUI, follow these steps:

  1. Navigate toSystem>High Availability.
  2. ClickAddon theNodestab.
  3. On theCreate HA Node页面,在Remote Node IP Addresstext box, type the NSIP Address (for example, 10.102.29.170) of the remote node.
  4. Ensure that theConfigure remote system to participate in High Availability setup复选框被选中。提供登录credentials of the remote node in the text boxes underRemote System Login Credentials.
  5. Select theTurn off HA monitor on interfaces/channels that are downcheck box to disable the HA monitor on interfaces that are down.

Verify that the node you added appears in the list of nodes in the Nodes tab.

Disable high availability monitoring for unused interfaces

The high availability monitor is a virtual entity that monitors an interface. You must disable the monitor for interfaces that are not connected or being used for traffic. When the monitor is enabled on an interface whose status is DOWN, the state of the node becomes NOT UP. In a high availability configuration, a primary node entering a NOT UP state might cause a high availability failover. An interface is marked DOWN under the following conditions:

  • The interface is not connected
  • The interface is not working properly
  • The cable connecting the interface is not working properly

Through CLI

To disable the high availability monitor for an unused interface by using the command line interface, follow these steps:

At the command prompt, type the following commands to disable the high availability monitor for an unused interface and verify that it is disabled:

  • set interface -haMonitor OFF

  • show interface

    Example

    > set interface 1/8 -haMonitor OFF Done > show interface 1/8 Interface 1/8 (Gig Ethernet 10/100/1000 MBits) #2 flags=0x4000  MTU=1514, native vlan=1, MAC=00:d0:68:15:fd:3d, downtime 238h55m44s Requested: media AUTO, speed AUTO, duplex AUTO, fctl OFF, throughput 0 RX: Pkts(0) Bytes(0) Errs(0) Drops(0) Stalls(0) TX: Pkts(0) Bytes(0) Errs(0) Drops(0) Stalls(0) NIC: InDisc(0) OutDisc(0) Fctls(0) Stalls(0) Hangs(0) Muted(0) Bandwidth thresholds are not set.

    When the high availability monitor is disabled for an unused interface, the output of the show interface command for that interface does not include “HAMON.”

Through GUI

To disable the high availability monitor for unused interfaces by using the GUI, follow these steps:

  1. Navigate to System > Network > Interfaces.
  2. Select the interface for which the monitor must be disabled.
  3. Click Open. The Modify Interface dialog box appears.
  4. In HA Monitoring, select the OFF option.
  5. Click OK.
  6. Verify that, when the interface is selected, “HA Monitoring: OFF” appears in the details at the bottom of the page.
Configure high availability
September 14, 2021
Contributed by:
C
September 14, 2021
Contributed by:
C

In this article

Site feedback | Privacy and legal terms | Cookie preferences | Consent settings
© 1999-Citrix Systems, Inc. All rights reserved.