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Archived Manual Chapter: 3-DNS Administrator Guide version 4.2: Adding a 3-DNS to an Existing Network
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11

Adding a 3-DNS to an Existing Network



Working with more than one 3-DNS in the network

When you are working with more than one 3-DNS in your network, and you want the systems to load balance to the same virtual servers, you can create your entire configuration on one system and then add the second system using the 3dns_add script. The 3dns_add script copies the entire configuration from the first system onto the second system, and synchronizes all of the settings between the systems. When you are finished, the first system acts as the principal system in the sync group, and the second system becomes a receiver system. (For more information about sync groups, see Working with sync groups, on page 6-19 .)

The following sections of this chapter describe the procedures you follow to add a 3-DNS into a network that already has at least one 3-DNS configured and working properly. If you are adding the first 3-DNS to your network, refer to Chapter 6, Essential Configuration Tasks .

Note: If you are adding a second 3-DNS to your network but do not want it to be in the same sync group as your first system, or you want the second 3-DNS 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 to your network

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

  • Physically install the second 3-DNS in its data center. (For more information on hardware installation, see Chapter 3, Setting Up the Hardware )
  • Run the Setup utility on the second system. (For more information on the Setup utility, see Chapter 4, Working with the Setup Utility , or if you are running the 3-DNS module on the BIG-IP, refer to the BIG-IP Reference Guide.)
  • Make the existing 3-DNS aware of the IP address, fully-qualified domain name, and data center location of the second 3-DNS. (See Making the existing 3-DNS aware of the additional system, on page 11-2 .)
  • Add the new 3-DNS to the sync group of the existing 3-DNS.

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

Warning: We strongly recommend that you run the 3dns_add script to add additional 3-DNS systems to your network if you are using a sync group. If you do not use the script, you risk overwriting your current configuration.

Installing the hardware and running the Setup utility

You can find detailed instructions on installing the 3-DNS hardware in Chapter 3, Setting Up the Hardware . Chapter 4, Working with the Setup Utility , includes detailed instructions on running the Setup utility. When you have finished this part of the setup for the second system, do not make any other changes to the configuration.

Note: If you are working with the 3-DNS module on the BIG-IP, please refer to the BIG-IP Administrator Kit for information on installing the hardware and running the Setup utility.

Making the existing 3-DNS aware of the additional system

Once you have installed the hardware and run the Setup utility on the new system, you add its configuration information to the existing 3-DNS (the 3-DNS that is already installed in your network). The existing system becomes the principal system in the sync group once you run the 3dns_add script on the new system.

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

  1. Add the second data center to the configuration.
  2. In the navigation pane, click Data Centers.
    The Data Centers screen opens.
  3. Click Add Data Center on the toolbar.
    The Add Data Centers screen opens.
  4. Add the information for the data center where you installed the new system, and click Update.
  5. Add the second 3-DNS to the configuration.
  6. In the navigation pane, expand the Servers item, and click 3-DNS.
    The 3-DNS List screen opens.
  7. Click Add 3-DNS on the toolbar.
    The Add New 3-DNS screen opens.
  8. Add the information for the new system and click Update.
  9. Add the new system to the existing system's sync group.
  10. In the navigation pane, click 3-DNS Sync.
    The System-Synchronization screen opens.
  11. Click Add to Group on the toolbar.
    The Add a 3-DNS to a Sync Group screen opens.
  12. Check the 3-DNS you just defined and click Add.
    The new system becomes a receiver in the sync group of the existing system.

You have now successfully added the new 3-DNS to the existing system's configuration and sync group. 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 either by using a remote secure shell session, or by using a monitor and keyboard connected directly to the 3-DNS.

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 Setup utility.
  3. To run the script, type 3dns_add at the command line.
    The script copies the entire configuration of the existing 3-DNS to the new system.

Verifying the configuration

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

  • Verify that each 3-DNS 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 systems in the sync group. 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 systems have time to synchronize with each other.

To verify that each 3-DNS 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. In the Server and Big3d columns, make sure the status is up, which is indicated by a small green ball.
  3. In the E/D column, make sure the systems are enabled.
  4. If the status of any of your systems is down, unknown, or unavailable, wait a few minutes and click Refresh. If status of the systems remains down, unknown, or unavailable, contact Technical Support for assistance.

To verify that the 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. In the Server column, make sure that the status of each server is up, which is indicated by a small green ball.
  3. If the status of any of your servers is down, unknown, or unavailable, wait a few minutes and click Refresh. If status of the servers remains down, unknown, or unavailable, contact Technical Support for assistance.

To verify that the 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. In the OK column, make sure that the status of each virtual server you configured is up, which is indicated by a small green ball.
  3. If the status of any of your virtual servers is down, unknown, or unavailable, wait a few minutes and click Refresh. 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

  1. At the command prompt, type nslookup and press Enter.
  2. Type the following command, where <IP_address> is the IP address of one of your 3-DNS systems, and press Enter.

    server <IP_address>

  3. 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 systems. Note that you can repeat the previous procedure for each wide IP you configured.

Note: This is the only verification task that you perform from the command line. The nslookup utility is part of DNS distributions. For more information on how to use the nslookup utility, please refer to the book, DNS and BIND, by Albitz and Liu.

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