5

Adding 3-DNS Controllers to the Network

Working with more than one 3-DNS Controller

When you are working with more than one 3-DNS Controller in your network, and you want the controllers to load balance to the same virtual servers, you can create your entire configuration on one controller and then add the second controller using the 3dns_add script. The 3dns_add script copies the entire configuration from the first controller onto the second controller, and synchronizes all of the settings between the controllers. When you are finished, the first controller acts as the principal controller in the sync group, and the second controller becomes a receiver controller. (For more information about sync groups, see Setting up sync groups .)

The following sections of this chapter describe the procedures you follow to add a 3-DNS Controller into a network that already has at least one 3-DNS Controller configured and working properly. If you are adding your first 3-DNS Controller to your network, please review Chapter 2 .

Note: If you are adding a second 3-DNS Controller to your network but do not want it to be in the same Sync Group as your first controller, or you want the second 3-DNS Controller to load balance to a different set of virtual servers, then do not use the 3dns_add script.

Preparing to add a second 3-DNS Controller to your network

Before you actually run the 3dns_add script on any additional 3-DNS Controllers you are adding to your network, you should complete the following tasks.

• Physically install the second 3-DNS Controller in its data center. (See the 3-DNS Controller Installation Guide for more information on the hardware installation.)
• Run the First-Time Boot utility on the second controller. (See the 3-DNS Controller Installation Guide for more information on the First-Time Boot utility.)
• Make the principal 3-DNS Controller aware of the IP address, fully-qualified domain name, and data center location of the second 3-DNS Controller. (See the following section, Making the principal 3-DNS Controller aware of the additional controller .)

Completing these tasks ensures that when you run the 3dns_add script, the second 3-DNS Controller successfully copies the configuration information from the first 3-DNS Controller.

Installing the hardware and running the First-Time Boot utility

You can find detailed instructions on installing the 3-DNS Controller hardware in the 3-DNS Controller Installation Guide. The Installation Guide also includes detailed instructions on running the First-Time Boot utility. When you have finished this part of the setup for the second controller, do not make any other changes to the configuration.

Making the principal 3-DNS Controller aware of the additional controller

Once you have installed the hardware and run the First-Time Boot utility on the new controller, you add its configuration information to the existing 3-DNS Controller. This controller becomes the principal controller in the sync group once you run the 3dns_add script on the new controller. Note that if you already have more than one 3-DNS Controller in a sync group, you should add the configuration information for the new controller to the principal controller in that sync group.

To add the new controller to the existing controller's configuration using the Configuration utility

1. First, you add the second data center to the configuration.
   1. In the navigation pane, click Data Centers.
      The Data Centers screen opens.
   2. Click Add Data Center on the toolbar.
      The Add Data Centers screen opens.
   3. Add the information for the data center where you installed the new controller, and click Update.
2. Next, you add the second 3-DNS Controller to the configuration.
   1. In the navigation pane, expand the Servers item, and click 3-DNS Controllers.
      The 3-DNS Controllers screen opens.
   2. Click Add 3-DNS Controller on the toolbar.
      The Add New 3-DNS Controller screen opens.
   3. Add the information for the new controller and click Update.
3. Finally, you add the new controller to the existing controller's sync group.
   1. In the navigation pane, click 3-DNS Sync.
      The System-Synchronization screen opens.
   2. Click Add to Group on the toolbar.
      The Add a 3-DNS to a Sync Group screen opens.
   3. Check the controller you just defined and click Add.
      The new controller becomes a receiver in the sync group of the existing controller.

You have now successfully added the new controller to the existing controller's configuration. The following sections describe how to run the 3dns_add script and verify the configuration.

Running the 3dns_add script

You can run the 3dns_add script on the new 3-DNS Controller either using a remote secure shell session, or using a monitor and keyboard connected locally to the controller.

To run the 3dns_add script

1. At the login prompt, type root.
2. At the password prompt, type the password you configured when you ran the First-Time Boot utility.
3. To run the script, type 3dns_add at the command line.
   The script copies the entire configuration of the existing 3-DNS Controller to the new controller.

Verifying the configuration

Once the script finishes, we recommend that you verify the following aspects of your configuration:

• Verify that each 3-DNS Controller has the necessary agents and daemons running.
• Verify that any servers you configured are up and available to receive load balancing requests.
• Verify that any virtual servers you configured are up and available to respond to requests.
• Verify that any wide IPs you configured are load balancing requests as you configured them.

You can perform these verification tasks on any of the controllers in the sync group, however, we recommend that you use the principal 3-DNS Controller. The following sections describe the verification process in detail.

Tip: You may want to wait a few minutes before you verify the configuration so that the 3-DNS Controllers have time to synchronize with each other.

To verify that each 3-DNS Controller has the necessary agents and daemons running

1. In the navigation pane, expand the Statistics item and click 3-DNS.
   The 3-DNS Statistics screen opens.
2. Click the Refresh button.
3. In the Server and Big3d columns, make sure the status is up, which is indicated by a small green ball.
4. In the E/D column, make sure the controllers are Enabled.
5. If the status of any of your controllers is down, unknown, or unavailable, wait a few minutes and click Refresh again. If status of the controllers remains down, unknown, or unavailable, contact Technical Support for assistance.

To verify that any servers you configured are up

1. In the navigation pane, expand the Statistics item and click Data Centers.
   The Data Centers Statistics screen opens.
2. Click the Refresh button.
3. In the Server column, make sure the status of any BIG-IP Controllers, EDGE-FX Caches, or hosts you configured is up, which is indicated by a small green ball.
4. If the status of any of your servers is down, unknown, or unavailable, wait a few minutes and click Refresh again. If status of the servers remains down, unknown, or unavailable, contact Technical Support for assistance.

To verify that any virtual servers you configured are up

1. In the navigation pane, expand the Statistics item and click Virtual Servers.
   The Data Centers Statistics screen opens.
2. Click the Refresh button.
3. In the OK column, make sure the status of any virtual servers you configured is up, which is indicated by a small green ball.
4. If the status of any of your virtual servers is down, unknown, or unavailable, wait a few minutes and click Refresh again. If status of the virtual servers remains down, unknown, or unavailable, contact Technical Support for assistance.

To verify that the wide IPs are load balancing properly

Note: This is the only verification task that you perform using the command line utility. The nslookup command is a standard UNIX command for DNS.

1. At the command prompt, type nslookup and press Enter.
2. Next, type the following:
   server <IP_address>
   
   where <IP_address> is the IP address of one of your 3-DNS Controllers, and press Enter.
3. Next, type the name of the wide IP (for example, news.domain.com) for which you want to verify load balancing and press Enter.

   If the virtual servers belonging to the wide IP appear in a pattern that reflects the load balancing mode you selected, you have successfully configured your 3-DNS Controllers. Note that you can repeat the previous procedure for each wide IP you configured.